Additive manufacturing of cellulose-based photopolymerizable resin with high strength and shape-memory

Domain: chemistry
Published: 2026-03-04
Editorial outcome: minor_revision

Abstract
As one of the core advanced manufacturing technologies, additive manufacturing is of high
application value in the aerospace, biomedical, and industrial component manufacturing fields.
Nevertheless, current additive manufacturing materials (e.g., petroleum-based resins) face
limitations such as poor stability, limited shape recovery, and insufficient mechanical properties,
which restrict sustainable manufacturing progress. Inspired by the stress-dissipation mechanism in
plant cell walls, we develop a cellulose-based photopolymerizable resin that delivers exceptional
stiffness-deformability synergy and spatiotemporally shape memory capability. These structures
integrate excellent mechanical strength and rapid recovery performance after deformation. The
additive manufacturing cellulose-based photopolymerizable resin material exhibits a synergistic
stiffness-deformability profile, achieving a compressive strength of 115.42 MPa and stiffness of
1404.16 MPa. These characteristics lay the foundation for specialized defense components, energy
absorption systems, and spatiotemporal memory materials.

Introduction
Additive manufacturing (AM), also known as 3D printing, represents one of pivotal
component fabrication methodologies in contemporary industry and constitutes a critically
prioritized technology for future industrial development1-3. AM enables materials to achieve
architected geometries, multifunctional integration, and intelligent responses, exhibiting
exceptional compatibility with rapidly advancing sectors such as aerospace, defense machinery,
and biomedical manufacturing4,5. Contemporary AM materials principally comprise brittle
polymers and rigid photopolymers, and despite their substantial stiffness, their toughness and
deformation capacity are inadequate6-10. Consequently, post-printed components undergo
irreversible deformation under load-induced damage, compromising their functionality and
reducing their service lifetime7,11,12. The annual waste volume of discarded AM products has
reached substantial levels with a persistent upward trend, posing serious challenges to material
utilization efficiency and environmental sustainability. In this context, developing high-strength
AM materials that combine rigid structural integrity with shape memory (flexible) performance
and rapid recovery capabilities remains a critical scientific challenge.

Cellulose constitutes the most abundant biomass resource in Earth's natural systems, offering
the advantages of renewability, ubiquitous availability, and low-cost sourcing13. At the same time,
the energy dissipation mechanism in plant cell walls - particularly through dynamic cellulose
microfibril sliding - serves as the fundamental strategy that enables plants to withstand external
mechanical stresses while maintaining structural toughness and environmental resilience14,15.
According to current research, cellulose has been primarily employed in digital light processing
(DLP)-AM materials as blended filler or minor additive. Previous studies on 3D printing of
biomass and its derivatives have shown that nanocellulose can be esterified with green small
molecules (e.g., citric acid) or blended with lignin and related components, thereby enabling direct
ink writing (DIW) printing of high-solids-content (≥25 wt%) structural parts with high strength
and good shape retention (flexural strength of 83–149 MPa and flexural modulus of 7–15 G Pa).16-
20 In contrast, in this work cellulose is used as the primary carbon source to directly synthesize
photocurable resins suitable for DLP printing (rather than aqueous paste-type DIW). While
maintaining high mechanical performance, these resins impart pronounced shape-memory
behavior and multi-cycle anti-fatigue capability to the printed structures, thereby overcoming the
limitations of existing DIW structural materials in terms of being “photopatternable, rapidly
formable, and capable of programmable deformation”.

Through mechanism-guided design that replicates the morphological preservation and stress
resilience mechanisms of natural plant cellulose. In plant cell walls, semi-disordered lamellar
architectures enable cellulose microfibrils to slide controllably through dynamic hydrogen bond
rupture and reconfiguration under external mechanical stress21-25. This hierarchical energy
dissipation mechanism effectively converts mechanical energy into thermal dissipation or other
non-destructive forms while maintaining structural integrity26-28. Tai4 and Zhang5 experimentally
demonstrated that cellulose microfibrils are the primary stress-bearing components during plant
cell wall deformation. Their work revealed that semi-disordered lamellar layers facilitate confined
cellulose microfibril sliding, which serves as the dominant energy dissipation mechanism in plant
cellular systems. This dynamic sliding behavior critically determines both the elastic-plastic
transition characteristics and deformation recovery thresholds of cell walls under multiaxial
loading conditions5,29.

Inspired by this dynamic mechanism, this paper designs a cellulose-derived photopolymer
network to achieve optimal balance between rigidity and flexibility in AM materials (Fig. 1). The
analysis reveals that under external forces, the semi-disordered microfiber network undergoes
loosening of intermolecular hydrogen bonds, enabling limited sliding that dissipates energy and
maintains morphological or structural stability. Furthermore, the synthesis of a photocurable resin
containing photosensitive groups capable of radical polymerization is presented. In particular, the
photocurable resin is synthesized using microcrystalline cellulose as the raw material through a
two-step reaction involving epichlorohydrin grafting and hydroxyethyl methacrylate (HEMA)
substitution. Using acrylamide as a crosslinking framework, the resin can be rapidly printed via
DLP at 5-10 s/layer. The resulting material combines a rigid carbon-chain framework with a
dynamically responsive cellulose-entangled structure, achieving an excellent rigidity-flexibility
balance. The AM cellulose-based photopolymerizable resin (CPPR-P) material exhibits
exceptional performance: high compressive strength (115.42 MPa), high elastic modulus (1404.16
MPa), and excellent mechanical cycling durability. In addition, it demonstrates outstanding shape
memory functionality, rapidly recovering its original state under both unidirectional stress (vertical
compression) and multi-directional stress (bus rolling) tests. This stiffness-deformability
synergistic material fulfills the demand in advanced applications for materials that simultaneously
offer high mechanical strength and superior damage-mitigating shape memory capabilities.

Results
Spatiotemporal memory and compressive properties of cellulose-based photopolymerizable resin
(CPPR). To meet diverse application requirements, AM resin must achieve high-precision rapid
printing of materials that can simultaneously resist both orderly uniaxial stresses and complex
multiaxial stresses while maintaining spatiotemporal memory capabilities for rapid recovery after
deformation induced by destructive external stresses30-34.

A 3D mechanical support structure of CPPR was designed and fabricated via DLP printing
(Fig. 2a), exhibiting well-defined geometric features and pristine architecture. A universal
mechanical tester (Fig. 2a) capable of generating uniform uniaxial stress and a large vehicle (bus;
Fig. 2b) with irregular multidirectional stress were used to simulate material stress and recovery
in different scenarios. During controlled uniaxial compression testing, the specimens were
compressed to their ultimate compressive state (75% strain). Upon release, they achieved rapid
structural and morphological recovery within 4-5 min. Throughout the compression-recovery
cycles (Movie S1), The CPPR-P demonstrated dynamic stress-adaptive behavior under overload
conditions while maintaining structural integrity without catastrophic failure. Under dynamic bus
loading (Movie S2), which generated disordered multidirectional stresses, specimens were
positioned directly in the wheel path to ensure full compressive traversal. After compression, the
3D mechanical support structure retained their mechanical support functionality while rapidly
recovering both morphology and architectural integrity. It should be noted that throughout the
model design, slicing, and DLP printing processes, high-fidelity rapid fabrication was achieved
without requiring auxiliary support structures. This demonstrates that the synergistic compatibility
between the CPPR resin material and optimized DLP printing parameters effectively streamlines
manufacturing workflows while significantly improving material efficiency and manufacturing
throughput.

The excellent mechanical strength and spatiotemporal memory capability of the 3D
mechanical support structure, combining rigidity with flexibility, depend highly on four factors: (i)
the limited sliding of the cellulose chains in the cured molecular structure, (ii) the dynamic fracture
and recombination of loose intermolecular hydrogen bonds under external stress, (iii) the rigid
carbon-chain skeleton formed by C=C bond reactions, and (iv) the multi-scale synergistic effects
between microphase-separated structures (Fig. 2c). Following the mechanism-guided design
cellulose-based photopolymerizable resin, precise layer-by-layer control of micro-nano level
curing is achieved via DLP printing. This enables precise structural and property control,
optimizing functional the characteristics of the material.

To characterize the compressive mechanical properties of CPPR-P, uniaxial compression tests
were conducted on a universal testing machine under different loading regimes. Herein, multiple
printable materials were fabricated: CPPR, a hydroxyethyl methacrylate-based
photopolymerizable resin without cellulose (HEMA-PR), and non-epoxidized CPPR (NE-CPPR).
Following GB/T 1041-2008 and its referenced standards, multiple cylindrical and prismatic
specimen sets were prepared and tested to obtain mean mechanical property values via replicated
experiments. Under uniaxial compression testing (Fig. 2d), the CPPR-P specimens demonstrated
exceptional mechanical performance, achieving a compressive strength of 115.42 MPa. Moreover,
CPPR-P exhibited an extended elastic regime (strain of ~80%), with complete deformation
recovery upon stress unloading and no permanent damage. These quantitative findings align with
the compressive recovery behavior observed in the 3D mechanical support structure (Fig. 2a,
Movie S1). During cyclic compression testing at 20%, 30%, 40%, and 50% strain amplitudes (Fig.
2e), all CPPR-P specimens rapidly stabilized into steady-state responses, exhibiting significant
energy dissipation and cyclic stability, which are critical characteristics for shape-memory
functionality and recovery performance. In addition, CPPR-P achieved dynamic stability in energy
dissipation within each cycle (Fig. 2f), with no observable strain softening across different strain
conditions. This indicates that CPPR-P has consistent recovery and shape-memory capabilities
over a broad strain range.

Tensile properties, curing process, and simulation results. In conventional photocured AM resins,
the crosslinking/curing degree and mechanical strength increase with photoinitiator concentration
and light exposure time. This relationship applies also to the CPPR photocured resin, which can
rapidly generate radicals and undergo crosslinking polymerization after reaction initiation, curing
rapidly within 5-10 s. Samples made of CPPR, HEMA-PR, and NE-CPPR were prepared and
uniaxial tensile tests were conducted under different loading conditions using a universal
mechanical testing machine (Fig. 3a). In cyclic tensile tests (Fig. 3b), the CPPR-P samples
exhibited a low-damage behavior dominated by elastic deformation, with clear energy absorption
and shape recovery. It was observed that after multi-cycle tension, samples remained in the elastic
stage with no structural damage. On the other hand, the printing sample of NE-CPPR entered the
plastic buckling stage after the first cycle, undergoing permanent damage. Moreover, the printing
sample of NE-CPPR exhibited significant strain softening and high energy dissipation during
cyclic stretching, indicating limited deformation recovery capability and poor fatigue resistance.
While the printing sample of HEMA-PR completely lacked cyclic recovery functionality, CPPR-
P demonstrated superior performance in terms of the maximum stress it could reach across
successive cycles (Fig. 3c). In multiple cyclic tests, CPPR-P stress could be maintained at nearly
100%, indicating its excellent cyclic recovery performance and fatigue resistance. In contrast,
HEMA-PR and NE-CPPR underwent rapid structural failure during the cyclic process and lost
their mechanical strength.

Tensile strength testing (Fig. 3d) revealed nonlinear stress-strain behavior in all specimens,
with distinct loading/unloading hysteresis loops indicative of significant energy absorption. Here,
the tensile strength of CPPR-P reached 25.16 MPa, significantly higher than that of the printing
sample of NE-CPPR (4.55 MPa). Although the tensile strength of the printing sample of HEMA-
PR was as high as 27.71 MPa, it lacked cyclic recovery capability due to its highly rigid and brittle
structure. The printing sample of HEMA-PR can be slightly stronger at first pull, but brittle and
non-recoverable; CPPR-P achieves engineering-level strength and repeatable recovery due to its
cellulose-based photopolymerizable resin—this is why, for functional AM components, CPPR is
the more suitable material despite a modest Ultimate Tensile Strength (UTS) difference. The elastic
moduli of CPPR-P, printing sample of HEMA-PR and NE-CPPR were 1404.16 MPa, 1412.96
MPa, and 12.30 MPa, respectively (Fig. 3e). CPPR-P environmental adaptability (water-resistance)
was also assessed by completely immersing a sample in water for 100 days, and observing the
entire process (Fig. S1). Interestingly, throughout the 100-day immersion period, the CPPR-P
maintained its morphology and volume without exhibiting any significant changes. Furthermore,
the mechanical properties of CPPR-P immersed in water for 0, 50, and 100 days were determined.
According to the results (Fig. S2), the tensile strength of CPPR-P at days 0, 50, and 100 was 25.16
MPa, 22.55 MPa, and 42.94 MPa, respectively, demonstrating excellent water resistance. After 50
days of immersion, the tensile strength of CPPR-P remained similar to that of day 0, exhibiting
typical nonlinear stress-strain behavior and cyclic recovery capability. Remarkably, after 100 days
of immersion, the tensile strength unexpectedly doubled, which can be attributed to water-induced
secondary crosslinking and network densification. During this process, selective hydrolysis
optimizes the structure by breaking weak bonds and retaining strong ones. At the same time,
cellulose microfibrils undergo orientation-enhanced sliding followed by failure processes (Fig. S2
and Fig. S3). Nonetheless, at this point, CPPR-P exhibited an extremely short elastic stage, and the
slope of the linear segment was extremely high (indicating significant brittleness), suggesting
complete loss of deformation recovery capability. Even after such a long immersion period, CPPR-
P stiffness (Young’s modulus) remained almost unchanged: 1404.16 MPa on Day 0, 1202.47 MPa
on Day 50, and 1586.19 MPa on Day 100 (Fig. S3).

Uniaxial tensile testing was simulated along the X-X orientation to quantitatively capture the
steady-state stress-strain response via computational modeling (Fig. 3f). According to the
simulation results, the cured CPPR exhibited a tensile strength of 27.80 MPa and strain of 28.10%
along the X-X direction. These computational predictions agreed well with the experimental
measurements (25.16 MPa tensile strength), empirically substantiating the validity of the
established theoretical framework and research conclusions. Concurrently, the simulated sample
density stabilized at 1.19 g/cm³ (Fig. S4), exhibiting close agreement with the experimental one
(1.14 g/cm³).

In the photoinitiated radical polymerization process, 2,4,6-trimethylbenzoyl-
diphenylphosphine oxide (TPO) served as the photoinitiator to drive the polymerization reaction
(Fig. 3g). TPO dosage affects the concentration of subsequently generated free radicals, which in
turn controls the free-radical polymerization rate, the crosslinking degree in the final material, and
material uniformity and density35. Under ultraviolet (UV) irradiation at 405 nm, TPO undergoes
homolysis to form benzoyl and diphenylphosphinyl radicals. These radicals attack the monomer
double bonds (R1 and R2) in CPPR and acrylamide, initiating chain polymerization and forming
polymer chains. The HEMA-dominated rigid polymer backbone provides pronounced stiffness but
introduces inherent brittleness, thereby deteriorating strain recovery capacity—as evidenced by
HEMA-PR experimental results. Conversely, cellulose molecular chains form a crosslinked
network architecture that enables confined sliding, thereby overcoming this limitation and
endowing the material with synergistic stiffness-deformability properties. According to the
simulation results of the CPPR free-radical polymerization crosslinking reaction (Fig. 3h), under
DLP-printing-like conditions, the polymerization achieves stable crosslinked network formation
with controlled conversion kinetics.

Shear and rheological tests. Beyond providing exceptional control over compressive and tensile
properties, DLP printing further facilitates precise modulation of CPPR shear response and
rheological behavior. This capability enhances dimensional accuracy in complex architectures,
interlayer fusion quality, and dynamic load-bearing performance under operational stress
conditions. In AM, the rheological properties of materials affect not only structural precision and
interlayer bonding but also material stability and post-printing strength via microstructure
regulation. In addition, mechanical shear strength directly reflects interlayer adhesion, which is
critical for materials operating under interface stress conditions. The investigation and
optimization of these properties have advanced photopolymerization AM for manufacturing high-
precision complex structures.

In the present study, shear tests were conducted under different loading regimes using a
universal testing machine (Fig. 4a). Under shear stress loading, both CPPR and HEMA-PR printed
samples exhibited evident elastic stages and yield points (CPPR: 7%; HEMA-PR: 6%), indicating
that the material was in the linear elastic deformation stage and underwent reversible elastic
deformation under external forces (Fig. 4b). The shear strength values of CPPR-P, the printing
sample of HEMA-PR and NE-CPPR were 25.83 MPa, 25.30 MPa, and 2.47 MPa, respectively
(Fig. 4c). The CPPR-P exhibited a distinct yield plateau (7-10% strain) after reaching the yield
point, during which cellulose-mediated molecular chain sliding (microplastic flow) occurred,
enabling continuous stress dissipation and release. On the other hand, post-yielding, the printing
sample of HEMA-PR immediately entered the plastic deformation stage (brittle failure stage). The
printing sample of NE-CPPR sample exhibited a plateau region with shear stress values close to
zero, suggesting fluid-like behavior characteristics. Another intuitive expression of shear
performance is the maximum yield stress. A higher yield stress enables structural integrity
preservation under shear loading (CPPR: 2651.02 N;HEMA-PR: 2726.06 N; NE-CPPR: 237.60
N) (Fig.S5). Overall, CPPR-P demonstrated excellent shear performance, with high shear strength,
peak yield stress, and fracture strain, achieving an optimal strength-toughness balance under shear
conditions.

To evaluate the rheo-structural properties, the rheological behavior of both DLP-printed CPPR
cylindrical specimens and the cellulose-based photocurable print resin liquid (CPPR-L) was
characterized. The rheological test results for the DLP-printed CPPR cylindrical samples (Fig. 4d)
revealed that the initial storage modulus (G'), loss modulus (G''), and complex viscosity (η*)
reached first a high yield plateau (0-10% strain) with increasing shear load. Upon exceeding the
critical shear blocking strain, all three parameters exhibited a gradual degradation. It can be
observed that the G' and G'' values of CPPR-P remained high over a wide range of shear strains,
demonstrating superior stiffness and stability under varied deformation conditions. In addition, the
intersection point of G' and G'', i.e., the point where the storage and loss moduli are equal, occurred
at higher shear strains in CPPR-P, confirming its wide elastic deformation range. The rheological
tests of CPPR-L (Fig. S6) revealed that the viscosity decreased gradually with increasing shear
rate, indicating a gentle shear-thinning behavior. This smooth viscosity reduction enhances
printing stability by maintaining optimal flowability while minimizing printing defects caused by
abrupt viscosity fluctuations. Furthermore, CPPR resin demonstrated viscosity stability across a
wide range of shear rates, which helps preserve the dimensional accuracy and shape fidelity of
printed parts, especially during multi-layer printing of intricate and complex structures.

Comparison of CPPR resin characteristics and properties before and after AM solidification with
other mainstream materials. To verify the industrial applicability of AM CPPR materials with
synergistic stiffness-deformability characteristics, comprehensive multi-dimensional performance
evaluation under operational conditions remains essential. To this end, comprehensive
comparative studies on CPPR-P, UV-curable epoxy resin (UVEP), polyamide nylon (PA), and
thermoplastic polyurethane elastomer (TPU) were conducted. These evaluations included ultimate
compression recovery (shape-memory function), compressive strength, cyclic compression,
tensile strength, and cyclic tension tests, as well as comparative analysis of material stiffness
(elastic modulus). In the compression recovery test (Fig. 5a and Movie S3 and S4), the 3D
mechanical support structure of CPPR manufactured via AM was compressed to the maximum
deformation state. The 3D mechanical support structure was able to quickly recover its shape and
morphology within 4-5 min after stress release. Conversely, during the initial testing phase, the
UVEP specimen underwent abrupt structural fragmentation upon stress application, exhibiting
catastrophic fracture that excluded any recovery potential. Although PA maintained partial
structural integrity during the experiment, its structure failed after it was compressed to its
maximum deformation state, leading to permanent deformation. After stress release, PA lost its
shape memory and recovery functions. Lastly, TPU proved unsuitable for fabricating the 3D
mechanical support structures required in this study via AM.

In the comparative assessment of compressive strength (Fig. 5b), CPPR-P demonstrated
significantly superior performance, achieving an exceptional 115.42 MPa, outperforming UVEP
(86.79 MPa), PA (49.02 MPa), and TPU (1.89 MPa). This indicates that CPPR-P can withstand
higher external stresses while maintaining structural integrity. Moreover, the cyclic compression
tests confirmed the excellent cyclic reversible elasticity at room temperature of the material (Fig.
5c). During repeated cyclic compression tests, CPPR-P consistently maintained a distinct elastic
behavior without structural failure, maintaining full specimen extension and recovery across all
loading/unloading cycles. The unique shape memory property of CPPR-
P is also absent from other materials. We obtain Shape fixation rate (Rf) = 60.5% ± 4.6%, Shape
recovery rate (Rr) = 94.5% ± 2.5%, and Trigger/switch temperature (t_r) ≈ 60–70 s at 100 °C.
No sample fractured during programming or recovery. (Table S1 “Shape-memory tests” and Movie
S5) In contrast, TPU exhibited a pronounced strain-softening behavior, which can be attributed to
interfacial debonding and internal crack initiation and propagation, leading to gradual recovery
capacity degradation. Meanwhile, neither UVNEP nor PA demonstrated any measurable cyclic
recovery capacity. These characteristics are clearly evidenced in the cyclic compression energy
dissipation profiles (Fig. 5d), where CPPR-P rapidly stabilizes into a consistent energy dissipation
plateau. Furthermore, the stiffness of CPPR-P (elastic modulus: 1404.16 MPa) maintained a
significant advantage over PA (650.08 MPa) and TPU (37.31 MPa), while being comparable to
UVEP (1418.05 MPa) (Fig. S7 and S8). CPPR-P demonstrated exceptional energy dissipation
capacity and cyclic recovery performance in both tensile testing (Fig. S9) and cyclic tensile energy
dissipation profiles (Fig. S10). Overall, the excellent mechanical strength and cyclic recovery
performance of CPPR resin significantly broaden its potential real-life applications while
improving its service life and reducing usage costs.

Subsequently, other important properties of CPPR-P were characterized and analyzed to
investigate and determine its applicability and stability over a wide application field range.
Through structural composition characterization, the reaction mechanism and memory recovery
function of CPPR-P were validated. Dynamic mechanical analysis (DMA; Fig. 5e) revealed the
loss-modulus maximum near ~90 °C (≈Tg) indicates the primary α-relaxation of the crosslinked
network, indicating the superior mechanical energy storage and elastic performance of CPPR-P
below 100°C. The loss modulus (E'') peak at 90°C (near Tg) signified maximum energy dissipation
through molecular chain relaxation and sliding, indicative of crosslinked network homogeneity.
Consistent with a load-bearing covalent network with restricted segmental mobility. Furthermore,
the peak magnitude of the loss factor (tanδ) reflects the energy dissipation capacity of CPPR-P. Its
prominent peak at TG transition demonstrates exceptional damping performance, rendering it
suitable for vibration attenuation and energy-absorbing applications.

Thermal analyses via differential scanning calorimetry (DSC; Fig. 5f) and derivative
thermogravimetric analysis (DTG; Fig. 5g) revealed the exceptional thermal stability of CPPR-P,
with onset decomposition temperatures above 250°C. Tg shifts upward and ΔCp across Tg
decreases after curing, evidencing reduced chain mobility and higher network density; the
transition width remains moderate, suggesting a reasonably homogeneous network rather than a
broad phase mixture.

Furthermore, scanning electron microscopy (SEM; Fig. S11) and X-ray diffraction (XRD; Fig.
S12) analyses of AM-fabricated CPPR-P sample interfaces revealed a homogeneous dense and
stable microstructure. These observations confirm the exceptional printability and process
compatibility of CPPR resin in AM, directly explaining its demonstrated outstanding mechanical
strength and shape memory performance.

Other, CPPR-P absorbs water but retains integrity and reaches a plateau swelling of ≈ 26–
29 % ( Swelling test; Table S2), indicative of a densely crosslinked acrylate–cellulose network
with limited free volume. The modest ≈ 17 % mass loss after 48 h likely reflects extraction of
residual oligomers/sol fractions plus minor hydrolysis of ester linkages near the surface
(Hydrolytic mass-loss; Table S3); the absence of disintegration corroborates the robust covalent
crosslink density.

Together with our mechanical data, these results support CPPR-P as a water-stable, high-
strength photoresin suitable for printed parts operating in humid/aqueous environments. These
results confirm that the CPPR resin crosslinked network is water-stable (no disintegration) while
allowing controlled water uptake, consistent with its covalent network plus reversible H-bonding.

Methods
Materials. Microcrystalline cellulose was purchased from Shanghai Macklin Biochemical
Technology Co., Ltd. Dimethyl sulfoxide (DMSO), epichlorohydrin (ECH), sodium hydroxide
particles, hydroxyethyl methacrylate (HEMA), acrylamide, and ethylene glycol diacrylate
(EGDMA) were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Ultra-
pure water was prepared in our laboratory. N, N'-Methylene Bisacrylamide (MBA) was purchased
from Tianjin Guangfu Fine Chemical Research Institute, while (2,4,6-trimethylbenzoyl)
diphenylphosphine oxide (TPO) was purchased from Shanghai Titan Scientific Co., Ltd.

Product synthesis and characterization. The supplementary material includes detailed synthesis
procedures and characterization data for the polymer, including reaction equations, spectra
analyses, and chromatograms.

Synthesis – Step 1 the prepared process of MCC epichlorohydrin (Fig. S13). First, an epoxide ring-opening
reaction occurs between the cellulose chains and epichlorohydrin. Briefly, 2 g of pretreated microcrystalline
cellulose (MCC) was swollen and uniformly dispersed in 70 mL of DMSO and maintained at 50 °C in a water
bath until a homogeneous suspension was obtained. Epichlorohydrin (40 mL) was then placed in a dropping
funnel and added dropwise at a rate of 10 mL h⁻¹. Subsequently, 15 mL of 30 wt% aqueous NaOH solution was
added dropwise over 30–45 min using a dropping funnel. The mixture was then heated to 80–85 °C and allowed
to react for a further 4 h. After cooling the reaction system to room temperature, the functionalized MCC
precursor was obtained. Under alkaline conditions at 80 °C, the epoxide group of epichlorohydrin undergoes a
ring-opening reaction to generate reactive sites, at which point the primary hydroxyl group at the C6 position of
cellulose reacts with it. The resulting product is named as MCC-E. After completion of the epichlorohydrin
ring-opening grafting, the key workup objective is to eliminate residual epichlorohydrin, which is volatile. The
reaction mixture is cooled to room temperature and the remaining epichlorohydrin is removed by rotary
evaporation (Vacuum degree 220-250Pa, 75 ℃, rotation speed 20, time 45 minutes) under reduced pressure
until a constant mass (or no further condensate) is observed. This step effectively prevents carryover of unreacted
ECH into Step 2 and ensures safe handling and reproducibility.

Synthesis – Step 2 the synthetic of Cellulose-based photopolymerisable resin (CPPR) precursor (Fig. S14). On
the basis of the precursor obtained in Step 1, free-radical photoreactive groups were grafted onto the cellulose
backbone. The product from Step 1 was transferred into a 500 mL round-bottom flask, and 0.5 wt%
methanesulfonic acid (CH₃SO₃H) was used as a catalyst. Then, 50 wt% hydroxyethyl methacrylate (HEMA)
(C₆H₁₀O₃) was added to introduce the free-radical photoreactive grafting groups, and the mixture was stirred at
70 °C in a water bath for 6 h. After completion of the reaction, the system was cooled to 50 °C and maintained
for a further 4 h to ensure complete conversion. The resulted product is cellulose-based photopolymerizable resin
(CPPR) precursor used for DLP additive manufacturing. After the HEMA grafting reaction, the workup aims to
remove (i) unreacted HEMA and (ii) the acid catalyst. We accomplish this by a combination of reduced-pressure
rotary evaporation (Vacuum degree 500-600Pa, 60 ℃, rotation speed 20, time 60-90 minutes) (to remove
residual HEMA) and neutralization (Add triethylamine dropwise at room temperature (1.05 equivalents relative
to the acid), and stir for 10-15 minutes, to quench the acid catalyst. And the mixture was passed through a short
plug of basic alumina to capture the residual acid /salts.), followed by brief vacuum treatment to remove trace
volatiles.

Synthesis – Step 3 the synthetic of cellulose-based photocurable print resin liquid (CPPR-L) (Fig. S15). The
reaction namely the photo-initiated free-radical polymerization of the CPPR resin. First, 150 mL of the above-
prepared CPPR resin monomer was transferred into a 500 mL round-bottom flask, and 15 mL of “ethylene glycol
dimethacrylate (EGDMA)” was added as a reactive co-monomer for the subsequent free-radical polymerization.
The mixture was stirred at 50 °C until complete dissolution. Afterward, the temperature was lowered to 30 °C
(to avoid premature partial polymerization caused by excessive temperature), and 40 wt% acrylamide (C₃H₅NO)
was added as a crosslinker, The reaction was allowed to proceed with stirring at 30 °C for 30 min. Subsequently,
0.1 wt% N,N′-methylenebisacrylamide (MBA) was introduced, and the mixture was stirred for another 30 min.
Finally, 0.5 wt% TPO was added as the photoinitiator, and stirring was continued until a homogeneous cellulose-
based photocurable print resin liquid (CPPR-L) capable of undergoing UV-induced free-radical polymerization
was obtained. The CPPR-L2 and CPPR-L3 were fabricated according to the different contents of CPPR and
acrylamide. HEMA-PR refers to photocurable print resin only with HEMA. NE-CPPR refers to CPPR without
MCC epichlorohydrin step. Removal of extractables and ensuring full cure: Step 3 produces a photocurable resin
by formulation; therefore, “product purification” relevant to materials testing is performed on the printed parts.
The as-printed objects are washed in anhydrous ethanol to remove unreacted/soluble residues at the surface,
followed by 405 nm & 5min post-curing to drive conversion to completion before characterization.

Description of the components of various resins used in this work (Table S4).

DLP additive manufacturing. A MiiCraft Ultra 150 3D printer was used for AM using the CPPR
material. The DLP parameters were set as follows: layer thickness of 50 μm, exposure time per
layer of 8 s, five base layers with an exposure time of 13 s, five buffer layers, and light-machine
power of 7.5 mW·cm⁻². After printing, the samples were placed in anhydrous ethanol to remove
excess liquid resin and then stabilized in a UV curing chamber (405 nm) for 5 min. The resulted
product is named CPPR-P.

The detailed printing parameters for the other resin formulations used in this work are summarized
in the table S5.

Characterization

NMR Spectroscopy. Nuclear magnetic resonance (NMR) spectroscopy was conducted using a
Bruker AVANCE III 500 MHz NMR spectrometer. The samples were dissolved in deuterated
dimethyl sulfoxide (DMSO-d6) for 10 min. The mixture was cooled to room temperature and then
filtered through a 0.45-μm filter membrane to obtain a clear filtrate suitable for NMR studies.

FTIR spectroscopy. Fourier-transform infrared (FTIR) spectroscopy was performed using a
WQF-510A spectrometer in attenuated total reflectance (ATR) mode. FTIR spectra were acquired
across the infrared range (4000–400 cm⁻¹) with 32 scans per sample.

XRD. X-ray diffraction (XRD) analysis was performed using a Shimadzu 6100 diffractometer to
identify the characteristic peaks and determine material crystallinity. The scanning parameters
were: angular range of 5°–65° (2θ); scan rate of 4° min⁻¹.

GPC. Gel permeation chromatography (GPC) was performed with an Agilent PL GPC50
instrument. GPC measurements were carried out on the soluble extractable fraction of the printed
samples using deuterated DMSO as the mobile phase (GPC measurements were performed on the
DMSO-soluble (extractable) fraction of the printed samples, rather than the entire crosslinked
network). The mass concentration of the test solution was 0.10 mg mL-1, the test volume was 100.0
μL, the flow rate was 1.0 mL min-1, and the column temperature was 40°C. DMSO (DMSO-d₆ in
our measurements) was used to dissolve the extractables and as the eluent.

Micro-morphology analysis. The surface morphology of the samples was observed and studied
via scanning electron microscopy (SEM; HT7800, Hitachi, Japan) in secondary electron mode
with an acceleration voltage of 20.0 kV.

Dynamic thermal performance analysis. Thermogravimetry-differential scanning calorimetry
(TG-DSC) analysis was performed using a Netzsch STA 449 F3 simultaneous thermal analyzer to
assess the dynamic thermal behavior of samples before and after AM. Specimens weighing 5-8 mg
were heated from 20°C to 800°C under nitrogen atmosphere at a controlled heating rate of 20
K·min⁻¹. Baseline correction was conducted by constructing pre- and post-transition baselines
(linear segments) and subtracting instrumental drift; second heating scan is shown after the first
heat/cool cycle to remove thermal history.

Dynamic mechanical analysis. The glass transition temperature, storage modulus, loss modulus,
and loss factor curves of the samples were obtained using a Q800 dynamic mechanical analyzer
(TA Instruments). Measurements were conducted under nitrogen atmosphere over the temperature
range of 25°C-500°C, with a heating rate of 10°C min−1 and frequency of 1 Hz.

Rheological performance testing. The rheological properties, such as storage modulus (elastic
modulus) G', loss modulus G'', loss factor tan δ, and complex viscosity, of the CPPR materials
before and after AM were assessed using a HAAKE MARS60 rheometer. Tests were conducted at
room temperature with a shear rate range of 0.01-1000 s-1.

Mechanical performance testing. An electronic universal testing machine (SHIMADZU AGS-
X 10kN) was used to determine the mechanical properties of the AM CPPR samples. Tests
included cyclic compression, compressive strength, cyclic tensile strength, tensile strength, and
shear performance measurements. Five replicates were tested for each condition, with reported
values representing averages. The tensile specimen used dumbbell shaped standard specimens
(thickness: 2mm; width: 4mm; gauge length: 50mm), and the compression and shear specimens
used rectangular standard specimens (length: 10mm; width: 10mm; height: 25mm), with a testing
rate of 10mm/min.

Swelling test. DLP-printed CPPR bars (rectangular, same geometry as mechanical tests) were
dried under vacuum at 50 °C to constant mass to obtain W (𝑊 ). Specimens were immersed in
0 dry
DI water (pH ≈ 7.0, 25 ± 0.5 °C) for 6, 12, 24, 48 h. At each time, samples were gently blotted
with lint-free tissue for 60 s and weighed immediately to obtain 𝑊𝑠(𝑊 ). The swelling ratio
wet
was calculated as
𝑆𝑅(%) = (𝑊wet−𝑊dry)/𝑊dry × 100%.
(1)
For each time point, record the same sample size n = 5, data are reported as mean ± SD; an
observation of dissolution/disintegration (Yes/No) was recorded.

Hydrolytic mass-loss. After 48 h immersion (conditions above reaching hydrolysis/swelling
equilibrium), specimens were rinsed, dried to constant mass at 50 °C, and weighed to obtain 𝑊 .
1
The mass-loss fraction was
𝑀𝐿(%) = (𝑊0−𝑊1)/𝑊0 × 100%,
(2)
where 𝑊 is the pre-immersion dry mass. 𝑛 = 5; results are given as mean ± SD, and the absolute
0
mass loss (g) is tabulated.

Shape-memory effect (SME) protocol. printed CPPR bars (DLP, 50 μm layers; 8 s per layer; 5
base layers at 13 s; 405 nm post-cure 5 min) were heated to T_prog = 100 °C ~ Tg+10 °C (Tg near
90 °C by DMA), deformed to a target strain, cooled under load to 25 °C, unloaded to obtain the
fixed strain (ε_fixed), and then reheated to T_sw = 100 °C for free recovery. We report Rf and Rr
as:
𝑅𝑓 = 𝜀fixed/𝜀max × 100%, (3)
𝑅𝑟 = (𝜀fixed−𝜀residual)/𝜀fixed × 100%
(4)
with n = 5 specimens (mean ± SD), and the recovery time t_r (≥90% recovery).

Simulation. Computational simulations of the CPPR curing process and material properties were
performed using Materials Studio (Version 2023, Dassault Systèmes). Initial reactant models were
constructed and subjected to electronic/geometric optimization with proper force field assignments.
Subsequently, the crosslinking and curing reactions were simulated (Temperature: 298 K; Pressure:
1 × 10⁻⁴ GPa; Number of steps: 1,000,000 steps; Time step: 1 fs.), with continuous monitoring of
the crosslinking degree, ring penetration, and molecular structure to verify the reaction progress
and structural validity. Lastly, the crosslinked products underwent geometric optimization,
annealing, and kinetic simulations, with data collected for subsequent analysis and interpretation36-
42.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "Zhao et al., in the revised manuscript entitled “Additive manufacturing of biomimetic biomass-derived materials with excellent mechanical performance and shape memory” [Manuscript ID: NCOMMS-25-54659-T], present and interesting approach to develop new photocrosslinkable materials with improved sustainability using cellulose derivatives. The manuscript builds upon the authors hypothesis that plant cell walls dissipative mechanism can be explored to create bio-inspired materials with superior mechanical properties.\n\nThe study is interesting and the research, analysis and synthetic work is certainly, of interest to a large readership. While the manuscript presents an interesting approach to the research question, there are significant scientific issues that need to be thoroughly addressed to meet the standards expected by a journal of this level.\n\n1) There are critical methodological details missing. One of them is the synthetic route towards the obtainment of the photocurable resin. Figures 9, 10 and 11 from SI do not provide sufficient detail to allow the reproduction of the reaction. This information should be added to the manuscript.\n2) The characterization of the precursors (by both FTIR and NMR) does not allow the confirmation of the functionalization of the MCC precursor. What was the calculated degree of substitution of the polymeric precursor? 13 C NMR can be provided useful information.\n3) What is the constitution of the uncured CPPR liquid resin (UC-CPPR)? Does it already contain the AM monomers mentioned in line 95? If so, the conclusions provided on Figure 17 from SI should be revised.\n4) The description of the resins used in this work should be also added. A table describing the amounts of each component on the resins (photoinitiator, MCC precursor, AM and crosslinker) must be provided in the manuscript.\n5) The DLP parameters should be provided with more detail. Was it the same for all the samples? What does a power of 125% means using standard irradiation units (mW/cm2)?\n6) The lattice 3D model used to print the samples should be added to SI.\n6) The nomenclature CPPR, HMPR and NE-CPPR is somewhat confusion. What does HPMR and NE-CPPR stand for?\nLines 156 and 157 provide some information, but more details are needed.\n7) From Figure 3d, it is possible to confirm the superior performance of HMPR in comparison with CPPR. The authors should elaborate more on this topic and provide more details about the composition of the HMPR resin.\n8) Swelling and hydrolytic degradation studies should be added.\n9) Figure 4c) considering the details, the viscosity seems too high for a DLP printing process. Weren’t there problems of printing resolution?\n10) How were the comparison standards (UVEP, PA and TPU) prepared? Also by DLP processes?\n11) DMA, DSC and TGA studies should be all revised.\n12) What tested in DMA, a printed sample or the resin? Which geometry was used? Data presented in Figure 5e does not match with what is described in lines 555 to 559.\n13) In Figure 21 from SI. What is the explanation for such a high weight remaining at 800ºC?\n14) Data from GPC should also be revised. Which solvent was used for the analysis? Were printed samples analyzed as stated in Figure 22 from SI?", "reviewer_2": "I co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.", "reviewer_3": "This paper reports a cellulose-based photopolymerizable resin (CPPR) with exceptional stiffness-deformability synergy and spatiotemporal shape memory capabilities. A bionic structure design approach was proposed, which transforms brittle photocurable 3D-printing materials into bio-inspired structures. This paper carries interesting results. However, there are some concerns regarding the synthesis of CPPR and its characteristics.\n\n1. Lines 64-67: The authors said, “However, the potential of using cellulose as a primary feedstock for directly synthesizing high-performance printable materials remains either unexplored or results in products with compromised mechanical and functional properties.” They did not recognize that nanocellulose has been 3D printed for structural materials by esterifying nanocellulose with green crosslinkers (Adv. Mater. Interf. 9(16), 2200280, May 2022; ACS Appl. Nano Mater. 5, 5680-5687, April 4, 2022; Carbo. Pol. 320, 121197, November 2023; ACS Omega 9(22) 23442-23450, May 2024; ACS Appl. Energy Mater. 8(1) 267–275, Jan 2025).\n2. The synthesis of ECHMCC, UC-CPPR, and CPPR: The authors did not explain clearly how to synthesize them step by step in Methods and Supporting Information. MCC is crystalline cellulose, and ECHMCC seems an amorphous cellulose, as shown in SI Figure 13. It seems that the authors dissolved MCC and performed epoxidation. Once it is true, then the cellulose solvent could influence all of products. The authors need to explain it.\n3. The authors should carefully use the acronyms by denoting full names, for example, ECHMCC.\n4. The mechanical properties of CPPR (compressive strength of 115.42 MPa and stiffness of 1404.16 MPa) are much lower than the nanocellulose 3D printed results. The authors need to compare their results with previously reported ones.\n5. Lines 345-346: “Moreover, the cyclic compression tests confirmed the excellent shape memory 345 recovery function of the material (Fig. 5c).” Fig. 5c shows nothing but pseudo-elastic (or super-elastic) behavior of CPPR material. Once CPPR has shape memory effect, then its quasi-plastic behavior (residual strain) needs to be shown. Otherwise, it may not be appropriate that CPPR has shape memory effect.", "reviewer_4": "The manuscript reports a cellulose-based photo-polymerizable resin for 3D printing that exhibits very promising structural integrity, stress dissipation, and shape-memory behavior. The topic is of interest and the experimental work is substantial. Overall, I believe the manuscript could be suitable for publication in Nature Communications after revision. Blow are my detailed comments.\n\n1. The authors should more clearly place this work in the context of existing 3D-printed shape-memory resins. A dedicated comparison (e.g., table + discussion) to recent reports is required, highlighting the most relevant metrics such as recovery time, recovery ratio, mechanical properties, switching temperature, cycle life, and printing resolution. This will help demonstrate the degree of advancement in a quantitative manner.\n2. Recovery time is a key performance index for shape-memory materials. The manuscript should report quantitative recovery data and compare directly with state-of-the-art resins. Please also describe the testing protocol in the Methods section and include appropriate statistics (sample size, mean +/- SD).\n3. Some panels are discussed out of sequence (e.g., Figs. 3 and 4: panel 3g/4e discussed before 3f/4b). In addition, Figs. 2–4 (compressive, tensile, shear tests) contain repetitive content and could be consolidated into one or two multi-panel figures for clarity.\n4. The statement in lines 69–72 that “our research group has developed …” appears incorrect, as the cited papers seem to be not from the authors’ group. Please review this wording or provide accurate references. A thorough check of the manuscript for similar citation or attribution errors is also necessary.\n5. The authors attribute the tensile-strength increase after 100 days in water to “hydrolysis optimizing the structure.” An alternative explanation could be additional hydrogen bonding or physical rearrangement. To clarify the mechanism, the authors may consider: (1) Providing stronger evidence for hydrolysis (e.g., FTIR, XPS, solid-state NMR, molecular weight analysis, and/or TGA); (2) Performing control immersions in hydrogen-bonding vs. non-hydrogen-bonding solvents and reporting the results; and/or (3) Discussing swelling behavior and mass change during immersion.\n6. In Fig. 3g and the supporting information, TPO appears to be confused with TPU. Please correct.\n7. The manuscript contains some repetition and excessive jargon, which reduces readability. Please streamline the text, remove redundancies, define abbreviations at first use (e.g., CPPR, HMPR, non-ECPR), and simplify language where possible.\n8. For all mechanical and shape-memory data, please report sample size (n), statistical measures (mean +/- SD), and test conditions (strain rate, sample dimensions, testing temperature). In addition, provide sufficient details on printing parameters (resin viscosity, printer model/settings, layer thickness, curing conditions) to ensure reproducibility."}, "author_response": "Point-by-point response to reviewers’ remarks\n(Blue: Reviewer’s remarks; Black: Our response)\nReviewer #1:\nGeneral Comments:\nZhao et al., in the revised manuscript entitled “Additive manufacturing of biomimetic\nbiomass-derived materials with excellent mechanical performance and shape memory”\n[Manuscript ID: NCOMMS-25-54659-T], present and interesting approach to develop\nnew photocrosslinkable materials with improved sustainability using cellulose\nderivatives. The manuscript builds upon the authors hypothesis that plant cell walls\ndissipative mechanism can be explored to create bio-inspired materials with superior\nmechanical properties.\nThe study is interesting and the research, analysis and synthetic work is certainly, of\ninterest to a large readership. While the manuscript presents an interesting approach\nto the research question, there are significant scientific issues that need to be thoroughly\naddressed to meet the standards expected by a journal of this level.\nOur response: We thank the reviewer for the positive comments, especially regarding\n“our work present and interesting approach to develop new photocrosslinkable\nmaterials with improved sustainability using cellulose derivatives”. We also appreciate\nthe reviewer's constructive technical comments, which have helped us to improve the\nquality of our manuscript.\n1. There are critical methodological details missing. One of them is the synthetic\nroute towards the obtainment of the photocurable resin. Figures 9, 10 and 11 from SI\ndo not provide sufficient detail to allow the reproduction of the reaction. This\ninformation should be added to the manuscript.\nOur response: After reading your comment, we realised that some essential\nmethodological details were missing from this section, preventing a clear description\nof the synthetic route used to obtain the photocurable resin. We have provided sufficient\nexperimental details to ensure reproducibility of the reaction, incorporating this\ninformation into the Methods section of the revised manuscript (lines 439–477).\nWe sincerely thank you for drawing our attention to this omission.\nSynthesis – Step 1 the prepared process of MCC epichlorohydrin.\nThe reaction shown in Fig. R1 (newly added Fig. S13 in the revised Supplemental\nMaterial). First, an epoxide ring-opening reaction occurs between the cellulose chains\nand epichlorohydrin. Briefly, 2 g of pretreated microcrystalline cellulose (MCC) was\ninitially allowed to swell and uniformly dispersed in 70 mL of DMSO and maintained\nat 50°C in a water bath until a homogeneous suspension was obtained. Subsequently,\nepichlorohydrin (40 mL) was placed in a dropping funnel and added dropwise at a rate\nof 10 mL h⁻¹. Then, 15 mL of 30 wt% aqueous NaOH solution was added dropwise\nover 30–45 min using a dropping funnel. The mixture was then heated to 80–85 °C and\nallowed to react for a further 4 h. After cooling the reaction system to room temperature,\nthe functionalised MCC precursor was obtained. Under alkaline conditions at 80°C, the\nepoxide group of epichlorohydrin underwent a ring-opening reaction to generate\nreactive sites, at which point the primary hydroxyl group at the C6 position of cellulose\nreacted with it. The resulting product is named as MCC-E.\nFig. R1. Epoxide ring-opening reaction between cellulose molecules and epichlorohydrin.\nNote：newly added Fig.S13 in the revised Supplemental Material\nSynthesis – Step 2 the synthetic of Cellulose-based photopolymerisable resin\n(CPPR) precursor .\nThe reaction depicted in Fig. R2 (Fig. S14) of the SI corresponds to Step 2 of the\nsynthesis. Based on the precursor obtained in Step 1, free-radical photoreactive groups\nwere grafted onto the cellulose backbone. The product from Step 1 was transferred into\na 500 mL round-bottom flask and 0.5 wt% methanesulfonic acid (CH₃SO₃H) was used\nas a catalyst. Subsequently, 50 wt% hydroxyethyl methacrylate (HEMA) (C₆H₁₀O₃) was\nadded to introduce the free-radical photoreactive grafting groups, and the mixture was\nstirred at 70 °C in a water bath for 6 h. After reaction completion, the system was\ncooled to 50 °C and maintained for a further 4 h to ensure complete conversion. The\nresulting product was a cellulose-based photopolymerizable resin (CPPR) precursor\nused for digital light processing (DLP) additive manufacturing (AM).\nFig.R2 Graft-free radical photosensitive reactive groups\nNote：newly added Fig.S14 in the revised Supplemental Material\nSynthesis – Step 3 the synthetic of Cellulose-based photocurable print resin\nliquid (CPPR-L).\nThe reaction exhibited in Fig. R3 (also see in Fig. S15) of the SI corresponds to Step 3,\nwhich details the photo-initiated free-radical polymerisation of the CPPR resin. First,\n150 mL of the CPPR precursor prepared in Step 2 was transferred into a 500 mL round-\nbottom flask, followed by the addition of 15 mL of ethylene glycol dimethacrylate\n(EGDMA) as a reactive co-monomer for the subsequent free-radical polymerisation.\nThe mixture was stirred at 50 °C until complete dissolution. Next, the temperature\nwas lowered to 30 °C (to prevent premature partial polymerisation), and 40 wt%\nacrylamide (C₃H₅NO) was introduced as a crosslinker. The reaction was allowed to\nproceed under stirring for 30 min at 30 °C. Subsequently, 0.1 wt% N,N′-\nmethylenebisacrylamide was introduced, and stirring continued for another 30 min.\nFinally, 0.5 wt% 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) was added as\nthe photoinitiator, and stirring was continued until a homogeneous Cellulose-based\nphotocurable print resin liquid (CPPR-L) capable of undergoing UV-induced free-\nradical polymerization was obtained. The CPPR-L2 and CPPR-L3 were fabricated\naccording to the different content of CPPR and acrylamide. HEMA-PR refers\nphotocurable print resin only with HEMA. NE-CPPR refers CPPR without MCC\nepichlorohydrin step.\nFig.R3 DLP-based UV curing via free radical polymerisation and crosslinking.\nNote：newly added Fig.S15 in the revised Supplemental Material\n2. The characterization of the precursors (by both FTIR and NMR) does not allow the\nconfirmation of the functionalization of the MCC precursor. What was the calculated\ndegree of substitution of the polymeric precursor? 13 C NMR can be provided useful\ninformation.\nOur response: We appreciate this suggestion. We agree that this analysis is crucial for\nenhancing the rigor and scientific validity of our experimental conclusions. In the\nrevised manuscript, we have complemented the FTIR and ¹H NMR data with ¹³C NMR\nspectra of both the native MCC and CPPR . We have estimated the substitution degree\n(DS = 0.82) based on the ¹³C integrals. These results are provided in Fig. R4 (newly\nadded Fig. S31 in the revised Supplemental Material) and summarised below.\n¹³C NMR evidence for MCC functionalisation:\nNative MCC (bottom trace) exhibits only the six anhydroglucose carbons (C1–C6) in\nthe ~60–105 ppm region, with no additional aliphatic or carbonyl signals. This confirms\nthat the starting cellulose is unsubstituted in Fig.R4. CPPR precursor (top trace) retains\nthe cellulose C1–C6 resonances but displays new, well-resolved signals characteristic\nof grafted methacrylate side chains: a photosensitive reaction site C=C at ~125–140\nppm, methacrylate methyl at 20~40 ppm, and additional O–CH₂ / O–CH signals in the\n~60–70 ppm region associated with the HEMA spacer. The simultaneous appearance\nof these new methacrylate-related carbons alongside, rather than the MCC backbone\nsignals, combined with the absence of cellulose or monomer signals, confirms that the\nmethacrylate groups are covalently attached to MCC rather than physically mixed in\nFig. R4.\nFig.R4 13C NMR analysis of MCC and CPPR monomers.\nNote：newly added Fig.S31 in the revised Supplemental Material\nDegree of substitution (DS) estimation:\nTo quantify the level of functionalisation, we integrated the ¹³C signals under\nquantitative conditions:\nThe anhydrous glucose unit (AGU) reference was taken as the sum of the six cellulose\ncarbons (C1–C6; six carbons per AGU). The substituent signal was taken as the sum of\nthe methacrylate-specific carbons (carbonyl C=O, vinylic C=C, and the methyl carbon;\na known number of carbons per substituent). Then, the DS of the CPPR precursor was\ncalculated using the standard relationship:\n(𝐼 /𝑛 )\nsub sub\n𝐷𝑆 =\n(𝐼 /6)\nAGU\nwhere 𝐼 and 𝐼 are the integrated areas and 𝑛 is the number of counted\nsub AGU sub\ncarbons per methacrylate unit.\nThe resulting DS value (0.82) lies in the moderate-substitution range (<1 substituent\nper AGU), providing a high density of photocurable methacrylate sites while\nmaintaining a continuous cellulose-derived backbone and suitable viscosity for DLP\nprinting.\nConsistency with FTIR and ¹H NMR:\nThe ¹³C NMR results are fully consistent with our previous FTIR and ¹H NMR data.\nThe FTIR spectrum confirms the successful functionalisation through the appearance\nof ester C=O and C=C bands (More details found Fig. S22, S24 and S27 in the revised\nSI), and ¹H NMR of the soluble fraction reveals C=C and methacrylate CH₃ signals\n(More details found Fig. S26 and S28 in the revised SI). Taken together, FTIR + ¹H\nNMR + ¹³C NMR provide direct and semi-quantitative confirmation that the MCC\nprecursor was successfully converted into a methacrylate-functional polymeric\nprecursor with a well-defined DS.\nBy supplementing the ¹³C NMR spectra of MCC and the CPPR precursor and\nestimating the DS from carbon signal integration, we demonstrate that the methacrylate\nside chains are covalently grafted onto the MCC backbone with a moderate DS.\nTogether with the original FTIR and ¹H NMR data, this now provides sufficient\nstructural and quantitative evidence to fully address the questions of true MCC\nfunctionalisation and the magnitude of the DS.\n3. What is the constitution of the uncured CPPR liquid resin (UC-CPPR)? Does it\nalready contain the AM monomers mentioned in line 95? If so, the conclusions provided\non Figure 17 from SI should be revised.\nOur response: We sincerely thank you for pointing out the confusing nomenclature\nand material descriptions, which arose from the inconsistency you pointed out in your\nComment #7. This issue indeed led to inconsistent naming of several resin systems,\nparticularly for the UC-CPPR resin, potentially hindering reader understanding. We\nhave fully adopted your suggestion and systematically revised the names and\nabbreviations of all materials throughout the manuscript, ensuring a more scientific and\nconsistent nomenclature to enhance overall clarity and readability.\nThe abbreviation for the CPPR liquid resin after grafting the photoreactive groups\n(previously denoted as UC-CPPR in now for Fig. S26 in the revised Supplemental\nMaterial) has been revised to “CPPR”, ensuring consistency throughout the manuscript.\nCPPR (formerly UC-CPPR) refers to the photocurable CPPR resin monomer used for\nDLP additive manufacturing, which does not contain the acrylamide crosslinker. The\nacrylamide is introduced as a crosslinker during the subsequent printing and shaping\nprocesses, i.e., it is introduced before printing with the CPPR resin monomer.\nFig.R5 1H NMR of CPPR and MCC-E following photosensitive group grafting.\nNote：Fig. S26 in the revised Supplemental Material.\n4. The description of the resins used in this work should be also added. A table\ndescribing the amounts of each component on the resins (photoinitiator, MCC\nprecursor, AM and crosslinker) must be provided in the manuscript.\nOur response:Thank you for this helpful suggestion. We fully accept this\nrecommendation and have added and standardised a “Resin recipe sheet” to the revised\nmanuscript (Table 1, line 477-480). Resin Formulations table provides the exact\ncomposition of each resin used in this study for transparency and reproducibility. The\ntable R1 details a cellulose-based photopolymerizable resin (CPPR) precursor, the\nacrylamide crosslinker, the photoinitiator (TPO). And ethylene glycol dimethacrylate\n(EGDMA) as a reactive co-monomer for the subsequent free-radical polymerisation\nwas added at a fixed amount of 15 mL for all experimental groups.\nTable R1 Resin component ingredient list\nSample Monomer Photoinitiator the acrylamide\nname (wt%) (TPO) crosslinker\n(wt%) (wt%)\nCPPR-L 60 0.5 ≈39.5\nCPPR-L2 70 0.5 ≈29.5\nCPPR-L3 50 0.5 ≈49.5\nHEMA-PR 60 0.5 ≈39.5\nNE-CPPR 60 0.5 ≈39.5\n5. The DLP parameters should be provided with more detail. Was it the same for all\nthe samples? What does a power of 125% means using standard irradiation units\n(mW/cm2)?\nOur response:Thank you for raising this important request. It is indeed crucial for both\nthe reproducibility and rigor of the work. We have addressed this by adding a dedicated\nPrinting Parameters table in Table R2 (newly added Table S4 in the revised manuscript),\nwhich lists the detailed printing settings for each resin. We have also clarified the\ncalibration from the printer “power percentage” setting to the surface irradiance. More\nspecifically, a printer power setting of 100% corresponds to a standard reference\nirradiance of ≈6.0 mW·cm⁻² for the MiiCraft Ultra 150 3D printer used. The 125%\nsetting corresponds to 7.5 mW·cm⁻². These details, including the printer model and\nwavelength (MiiCraft Ultra 150, 405 nm), are now summarised in Table R2. In addition,\nthe optimal printing parameters were not identical for all samples because the\ncomposition and component contents differ among the various resin formulations.\nAs regards sample uniformity, in the CPPR-based printing formulations and runs, the\ngeometric recipe (layer thickness and count) was kept constant. The exposure time\nand/or irradiance settings were moderately adjusted for the different formulations\n(HEMA-PR, NE-CPPR, CPPR-L2 and CPPR-L3) to achieve a balance between cure\ndepth and green strength under their distinct light absorption and photoreactivity\nprofiles. The specific settings for each resin are also summarised in Table R2. This\napproach follows the standard dose-control relation (E = I × t), maintaining the target\ncuring dose for a 50 μm layer while avoiding overcuring of fine features.\nTable R2 Detailed printing parameters for various types of resins\nSample Printing Layer Single- Printing Base Buffer Printing Print\nname moulding thickness exposure substrate exposure layer machine (fill)gaps\nmethod (µm) time (s) layers time (s) number power/ (mm)\ntemperature\nCPPR-L DLP 50 8 5 13 5 125% 0.1\nHEMA-PR DLP 50 4 5 10 5 100% 0.1\nNE-CPPR DLP 50 10 5 13 5 125% 0.1\nCPPR-L2 DLP 50 14 5 18 5 150% 0.1\nCPPR-L3 DLP 50 6 5 10 5 125% 0.1\nUVEP DLP 90 2.4 5 8 5 100% 0.1\nPA SLS 150 —— —— —— —— 30 w 0.1-0.2\nTPU FDM 200 —— —— —— —— 200 ℃ 0.1\nNote: Minimum optional Layer thickness of CPPR-L is 5 µm.\nSLS: Selective Laser Sintering\nThe printer power setting of 100% corresponds to a standard reference irradiance of ≈6.0\nmW·cm⁻² for the MiiCraft Ultra 150 3D printer used in our work.\n6. The lattice 3D model used to print the samples should be added to SI.\nOur response:We agree that a well-prepared 3D model file is fundamental to\nsuccessful printing, since it directly affects the build speed, printing accuracy, and final\nperformance of the 3D-printed parts. Therefore, it is necessary to provide our model\nsource files for complete reference.\nAccordingly, we have included the complete lattice 3D model source file of the printed\nsamples (“lattice_3D_model.max”) and a slice-ready file (“lattice_3D_model.stl”) in\nthe SI and associated supplementary files. The stl format is convenient for handling\nprior to being imported into the printer software. If requested, we can also provide the\n“.mii” file, which contains the fully integrated printing parameters and physical\ninformation, enabling direct printing on the MiiCraft 3D printer.\nFig.R6 Print the lattice 3D model of the sample.\n7. The nomenclature CPPR, HMPR and NE-CPPR is somewhat confusion. What does\nHPMR and NE-CPPR stand for? Lines 156 and 157 provide some information, but\nmore details are needed.\nOur response: Thank you for your suggestion. We have re-standardised the\nnomenclature using a more systematic and scientifically sound scheme to significantly\nimprove clarity and reproducibility. In particular, we retain CPPR as the main system\nname and harmonised the other abbreviations to the format “[chemical motif]-PR”,\navoiding overly long, stacked abbreviations. We also introduced suffixes (L/P) to\nindicate the physical state of the material. This yields a coherent and readable unified\nnaming/definition scheme across the entire manuscript.\nNow, HMPR is denoted as HEMA-PR (a cellulose-free photocurable resin containing\nonly HEMA) and NE-CPPR is explicitly defined as the non-epoxidised variant of CPPR\n(without the ECH step). Where appropriate, we have added the state suffixes: CPPR-L\n(uncured liquid CPPR resin feedstock) and CPPR-P (DLP-printed CPPR specimens).\nMoreover, ECHMCC is now called MCC-E, referring to MCC molecules grafted via\nECH epoxide ring-opening etherification. The More details can be found in newly\nadded Material Method section (line ) in the revised manuscript.\nAll abbreviations are introduced as “full name + abbreviation” at their first appearance\nin the main text and are subsequently used in abbreviated form only. In addition, the\nunified abbreviations are summarised in a dedicated “Abbreviations” Table S7 in the\nSI, and the same terminology is consistently applied throughout the text, figures, and\ncaptions.\nTable R3 Summary Table of Abbreviations.\nAbbreviation Abbreviation Full name\nNew name Old name\nCPPR CPPR Cellulose-based photopolymerisable resin precursor\nCPPR-L UC-CPPR Uncured CPPR resin feedstock\nCPPR-P (None) DLP-printed CPPR specimens\nHEMA-PR HMPR Cellulose-free photocurable resin containing only HEMA\nNE-CPPR NE-CPPR Non-epoxidised variant of CPPR (without the ECH step)\nMCC-E ECHMCC MCC molecules grafted via ECH epoxide ring-opening etherification\n8. From Figure 3d, it is possible to confirm the superior performance of HMPR in\ncomparison with CPPR. The authors should elaborate more on this topic and provide\nmore details about the composition of the HMPR resin.\nOur response: We appreciate the observation and have clarified both the composition\nof the HMPR (now denoted as HEMA-PR) control and the intended comparison metrics.\n(1)What Fig. R7a shows and what it does not\nUnder single-cycle tension, HEMA-PR indeed exhibits a slightly higher ultimate tensile\nstrength (UTS) (27.71 MPa) than CPPR-P (25.16 MPa) in Fig.R7 (also see Fig. 3d, 3b\nand 3c in the revised manuscript). Their elastic moduli are essentially comparable\n(HEMA-PR: 1412.96 MPa; CPPR-P: 1404.16 MPa). However, HEMA-PR lacks cyclic\nrecovery and rapidly fails under repeated loading, while CPPR-P maintains a near 100%\nstress level across all cycles with clear elastic recovery in Fig. R7b and 7c. These key\ndistinctions and quantitative values are now explicitly emphasised in the revised text.\nFig. R7 (a) Stress-strain curves obtained under tensile testing ; (b) Stress-strain curves obtained\nunder cyclic tensile testing; (c) Maximum stress evolution during cyclic tensile testing;.\n(2) HEMA-PR (formerly HMPR) composition and behavioural difference\nHEMA-PR is a cellulose-free photocurable control formulated using HEMA with the\nsame photoinitiator family (TPO) and auxiliary crosslinker (EGDMA) used in the\nCPPR system. The exact formulation is provided in the Resin Formulations table (Table\nR1), with units harmonised across all resin systems. The specific HEMA-PR recipe is:\nHEMA 60 wt% (reactive-solids basis), the acrylamide crosslinker ≈40 wt%, TPO 0.5\nwt% (of total resin), and the bifunctional additive/crosslinker (EGDMA) was added at\na fixed amount of 15 mL for all experimental groups. Mechanistically, the HEMA-\ndominated rigid backbone provides high stiffness but results in intrinsic brittleness,\nwhich severely deteriorates strain-recovery capacity. This is consistent with the\nHMPR/HEMA-PR experiments. In contrast, CPPR’s cellulose chains create a\ncrosslinked network characterised by confined sliding and abundant reversible H-\nbonding. This architecture couples high stiffness with recoverability and fatigue\nresistance. We have made this contrast explicit in the revised manuscript.\n(3) Fair benchmarking and processing details\nAll test samples were DLP-printed with identical geometry and gage dimensions. The\nprinting parameters for each resin are listed in Table R2. The default CPPR-L run used\n50 μm layers, 8 s per layer, 5 base layers at 13 s, and the specified 405 nm curing/post-\ncure. HEMA-PR was printed under its own listed irradiance setpoint to equalise cure\ndepth/green strength (dose control, E = I×t).\n(4) Framing the comparison in the manuscript.\nWe have clarified that the single-cycle UTS is not the sole or primary figure-of-merit\nfor this work. The target is the co-optimisation of strength and functional recoverability\nunder repeated loading. Thus, the manuscript now explicitly states: although HEMA-\nPR can reach a marginally higher UTS in one pull, it entirely lacks superelastic/cyclic\nrecovery or shape-memory capabilities. In contrast, CPPR-P delivers high strength with\nrobust multi-cycle recovery, which is the central advance demonstrated here (see Figs.\n3b–e and the companion cyclic/energy-dissipation data in the Suppplemently Fig. S10).\nTake-home message for the reader (in the revised manuscript 199-205 line): HEMA-\nPR is marginally stronger at the initial pull but is brittle and non-recoverable. CPPR-P\nachieves engineering-level strength and repeatable recovery due to its cellulose-based\nnetwork architecture. This is why, despite a modest UTS difference, CPPR-P is the more\nsuitable material for functional AM components. The paragraph concerning Figs. 3b–e\nhas been expanded to explicitly separate single-cycle strength from multi-cycle\nrecoverability/fatigue resistance, citing the exact numbers.\n9. Swelling and hydrolytic degradation studies should be added.\nOur response: We greatly appreciate your suggestion, which is highly beneficial for\nenhancing the scientific rigor of the article content and the credibility of the\nexperimental results. To address this, we have added both a water-swelling study and a\nhydrolytic mass-loss analysis on DLP-printed, fully cured CPPR-P bars. The new data\nand raw spreadsheets are provided as Fig. R8 and Table R4 (newly added Table. S2 in\nthe revised Supplemental Material). The key findings are:\nSwelling (DI water, 25°C): The DLP-printed, fully cured CPPR-P bars exhibit\nmoderate initial water uptake that subsequently plateaus. Across n = 5 specimens per\ntime point, the swelling ratio 𝑆𝑅 = (𝑊 −𝑊 )/𝑊 ×100% was ≈37–39% at 6 h,\ns 0 0\ndecreasing to a stable ≈26–29% at 12-24-48 h. No dissolution or disintegration was\nobserved at any time point up to 48 h. Thus, the DLP-printed specimens reached\nswelling equilibrium within a relatively short time (approximately 12 h). Even when\nimmersed for longer periods, they did not exhibit further water uptake or swelling,\nindicating that a stable state had been achieved in Fig.R8 and Table R4.\nFig.R8 Time-dependent swelling curves of samples.\nTable R4 Swelling test results and analysis.\nSample Time (h) W0 (g) Ws (g) Swelling Does it\nnumber ratio (%) degrade/disintegrate?\nn 1 6 1.11 1.52 36.94 No\nn 2 6 1.49 2.05 37.58 No\nn 3 6 1.26 1.79 42.06 No\nn 4 6 1.24 1.73 39.51 No\nn 5 6 1.50 2.07 38.00 No\nn 1 12 1.11 1.42 27.92 No\nn 2 12 1.49 1.93 29.53 No\nn 3 12 1.26 1.61 27.78 No\nn 4 12 1.24 1.57 26.61 No\nn 5 12 1.50 1.93 28.66 No\nn 1 24 1.11 1.42 27.92 No\nn 2 24 1.49 1.92 28.86 No\nn 3 24 1.26 1.60 26.98 No\nn 4 24 1.24 1.57 26.61 No\nn 5 24 1.50 1.94 29.33 No\nn 1 48 1.11 1.42 27.92 No\nn 2 48 1.49 1.90 27.52 No\nn 3 48 1.26 1.60 26.98 No\nn 4 48 1.24 1.57 26.61 No\nn 5 48 1.50 1.92 28.00 No\nTable R5 Mass-loss analysis.\nSample Treatment W (g) W (g) Mass loss Mass loss\n0 1\nnumber conditions rate (%) (g)\n(Time/h)\nn 1 48 1.55 1.27 18.06 0.28\nn 2 48 1.37 1.13 17.52 0.24\nn 3 48 1.22 1.02 16.39 0.20\nn 4 48 1.54 1.28 16.88 0.26\nn 5 48 1.53 1.27 16.99 0.26\nHydrolytic degradation (DI water, 25°C, 48 h): After rinsing and drying to constant\nmass, the mass-loss fraction 𝑀𝐿 = (𝑊 −𝑊 )/𝑊 ×100 % was ≈17±0.6%\n0 1 0\n(n=5). This mass corresponds to removal of low-molar-mass sol fractions and limited\nester hydrolysis at the network periphery. All specimens remained intact and could be\nhandled without damage.\nThe CPPR-P photopolymerisation network structure absorbs water but retains its\nintegrity, reaching a plateau swelling of ≈26–29%. This is indicative of a densely\ncrosslinked acrylate–cellulose network with limited free volume. The modest ≈17%\nmass loss after 48 h reflects the extraction of residual oligomers/sol fractions plus minor\nhydrolysis of surface ester linkages. Moreover, the absence of disintegration\ncorroborates the robust covalent crosslink density. Together with our mechanical data,\nthese results confirm that CPPR-P is a water-stable, high-strength photoresin suitable\nfor printed parts operating in humid or aqueous environments. Furthermore, they\nconfirm that the CPPR-P crosslinked network is water-stable (no disintegration) while\nallowing controlled water uptake, consistent with its covalent network plus reversible\nH-bonding.\nThe test details have been inserted in the Methods and referenced the new SI tables in the\nResults. The relevant tables and information have been added to the Supporting\nInformation as requested and the test and its results are now analysed and discussed in\nthe Discussion section (Fig. 5 in the revised manuscript, lines 391–402).\n10. Figure 4c) considering the details, the viscosity seems too high for a DLP printing process. Weren’t there problems of\nprinting resolution?\nOur response: Thank you for this helpful comment. We have now reported the absolute,\nsteady-shear viscosity of the CPPR-L (uncured liquid) measured with a rotational\nviscometer (NDJ-1B, 25°C, spindle #2, 60 rpm): η = 168 mPa·s. This value is\nwithin the printable window of our DLP setup. In addition, it is consistent with the\ngentle shear-thinning behaviour obtained from the rheology data in Fig.R9, where the\nviscosity decreases smoothly with increasing shear rate, ensuring good recoating/flow\nduring layer renewal. In the original manuscript text accompanying Fig. 4c, we have\nclarified that the curve describes the shear-rate-dependent viscosity of the CPPR-L,\nwhile Fig. R9b reports the viscoelastic moduli/η* of printed CPPR. The two panels\nquantify different states and test modes.\nImportantly, we did not encounter resolution issues in practice. Using the conditions\nprovided in the Methods (layer thickness 50 μm, 8 s exposure per layer, 5 base layers\nat 13 s, calibrated printer power), the resin successfully produced complex, high-fidelity\n3D features and intricate lattices with clean edges in FigR6c. This observation supports\nour rheology discussion (smooth shear-thinning supporting dimensional accuracy) and\nis consistent with the manuscript statements on printability and process compatibility.\nWe have reiterated these details and kept the per-resin printing parameters explicit in\nmain text (Methods; Table R2).\nFig. R9 (a) CPPR-L viscosity and (b) rheological test results. (c) Printed sample with high\nresolution and clarity.\nFor transparency, we have also specified the irradiance in mW·cm⁻² corresponding to\nthe device “percent power” in TableR 2. We note that dose control (E = I×t) was used\nto equalise the cure depth among all formulations; thus, resolution was governed by\ncontrolled exposure rather than by any excessive viscosity.\nOverall, the CPPR resin exhibited moderate viscosity (168 mPa·s at 25°C) with gentle\nshear-thinning, enabling reliable recoating. Under the reported DLP parameters, no loss\nof printing resolution was observed; instead, the resin consistently yielded high-fidelity,\nintricate architectures, as reflected in the figures and discussion of the manuscript.\n11. How were the comparison standards (UVEP, PA and TPU) prepared? Also by DLP processes?\nOur response: Thank you for raising this point. We have added Printing & Processing\nParameters in Table R6. (also see Supplemently Table S4), which lists the exact\nmanufacturing route and settings for each comparator. We have clarified that the three\nstandards (UVEP, PA, and TPU) were not all fabricated by the DLP process, but they\nwere prepared by the industry-typical process for each material to ensure realistic\nperformance baselines.\nTable R6 Detailed printing parameters for various types of resins\nSample Printing Layer Single- Printing Base Buffer Printing Print\nname moulding thickness exposure substrate exposure layer machine (fill)gaps\nmethod (µm) time (s) layers time (s) number power/ (mm)\ntemperature\nCPPR-L DLP 50 8 5 13 5 125% 0.1\nHEMA-PR DLP 50 4 5 10 5 100% 0.1\nNE-CPPR DLP 50 10 5 13 5 125% 0.1\nCPPR-L2 DLP 50 14 5 18 5 150% 0.1\nCPPR-L3 DLP 50 6 5 10 5 125% 0.1\nUVEP DLP 90 2.4 5 8 5 100% 0.1\nPA SLS 150 —— —— —— —— 30 w 0.1-0.2\nTPU FDM 200 —— —— —— —— 200 ℃ 0.1\nNote: Minimum optional Layer thickness of CPPR-L is 5 µm.\nSLS: Selective Laser Sintering\nThe printer power setting of 100% corresponds to a standard reference irradiance of ≈6.0\nmW·cm⁻² for the MiiCraft Ultra 150 3D printer used in our work.\nUVEP (UV-curable epoxy): Prepared as a vat-photopolymerised control (DLP) using\nthe same wavelength/photoinitiator family as the CPPR system. Layer thickness, per-\nlayer/base-layer exposure, and irradiance (mW·cm⁻²) are reported in Table 2.\nPA (polyamide, nylon): Prepared by selective laser sintering (SLS). Table 2 reports\npowder bed settings (layer thickness), laser power and scan recipe, and thermal\nsetpoints (preheat/bed) used for densification.\nTPU (thermoplastic polyurethane): Prepared by FDM/FFF. Table 2 specifies nozzle\ntemperature, layer height, raster/infill (100% infill for fair mechanical comparison),\nline spacing, and bed temperature.\nIn short, UVEP = DLP, PA = SLS, and TPU = FDM. The per-material parameters are\nfully enumerated in the main text (Methods; Table 2). This design reflects how these\nmaterials are actually deployed in practice, while our comparison methodology\n(identical geometry/conditioning/strain rate and 100% infill for FDM) ensures\nmethodologically fair benchmarking.\n12. DMA, DSC and TGA studies should be all revised.\nOur response: We agree that the original thermo-mechanical and thermal analyses\nrequired not only standardised criteria but also clearer comparative interpretation. To\nthis end, we have re-measured, re-processed, and re-plotted all datasets and added a\nproperty-focused comparison between the uncured resin (CPPR-L) and the AM-\nfabricated polymer (CPPR-P), unifying definitions across DMA, DSC, and TGA/DTG.\nThese revisions address the issues that existed in the original figures (Figs. 5e-g and SI\nFig. 26) prior to modification: (i) the data were not sufficiently clear due to the previous\ntesting procedures and conditions, resulting in difficult-to-distinguish curves and\nunclear key data points; (ii) a relatively narrow temperature range (25–300°C) led to\nincomplete data acquisition and apparent gaps in the dataset (Fig. 5e); (iii) the\nnomenclature was not sufficiently explicit, increasing reading and interpretation\ndifficulty.\n(1) DMA (printed; fully cured bars; N₂ environment) (also see Fig. 5d in the revised\nmanuscript)\nWhat changed: We now show E′/E″/tan δ on the same axis set; Tg is defined by\nthe tan δ peak (with E″ peak/E′-onset as secondary markers). Test window, ramp,\nand frequency are stated in Methods (Q800, 25 to 500°C, 10°C min⁻¹, 1 Hz).\nWhat it means: The loss-modulus maximum near ~90°C (≈Tg) indicates the\nprimary α-relaxation of the crosslinked network. Below 100°C the storage modulus\nremains high and relatively flat, consistent with a load-bearing covalent network with\nrestricted segmental mobility.\nInterpretation & differences: Compared to the uncured liquid (no network), CPPR-P\nexhibits a sharp α-transition and high E′ plateau in the service window (0–80 °\nC), rationalising the observed mechanical strength and the selected shape-memory\nprogramming window (T_prog≈100 °C ≳Tg). Note: The SME temperature\nreferencing DMA is now explicit in Methods/Results.\nFig. R10 The DMA analysis.\n(2) DSC (baseline-corrected; Tg by midpoint) (also see Fig. 5e in the revised\nmanuscript)\nWhat changed: We re-corrected the baselines and report DSC-Tg by the inflection\nmidpoint, cross-referenced to DMA-Tg (tan δ peak) for consistency.\nInstruments/ramps/atmospheres are now listed verbatim.\nWhat it means: In CPPR-L, a residual curing exotherm upon heating is now separated\nfrom the Tg step. In CPPR-P, this exotherm disappears since double bonds are\nconsumed during AM curing (consistent with the NMR statements of C=C\nconsumption).\nInterpretation & differences: After curing, Tg shifts upward and ΔCp across Tg\ndecreases, indicating reduced chain mobility and higher network density. The transition\nwidth (tan δ FWHM) remains moderate, suggesting a reasonably homogeneous\nnetwork rather than a broad phase mixture.\nFig. R11 The DSC analysis of CPPR-L and CPPR-P\n(3) TG/DTG (N₂) (also see Fig. 5g in the revised manuscript and Supplemently Fig. S29)\nWhat changed: We have standardised T and T_onset (tangent-intersection) and\n5%\nreport char yield at 700/800°C. DTG peak labels were corrected. Methods give STA\nmodel/ramps/atmosphere (Netzsch STA 449 F3, 20–800°C, 20 K min⁻¹, N₂).\nWhat it means: CPPR-P shows onset decomposition >250°C (main 250–400°C),\nconsistent with a cellulose-derived covalent network. Non-zero residue at 700–800°\nC is expected under nitrogen due to carbonaceous char and minor inorganic ash.\nInterpretation & differences (CPPR-L vs CPPR-P): After curing, the low-\ntemperature mass loss (<200–250°C) is suppressed (due to volatiles/monomer\nremoval), the main DTG peak shifts slightly higher (enhanced thermal stability from\nnetwork formation), and char yield increases, which is consistent with constrained\npyrolytic fragmentation and higher aromatic/heteroatom-assisted char formation in the\ncrosslinked structure.\nFig. R12 The (a) TG and (b) DTG analysis of CPPR-L and CPPR-P\nOverall: These revisions provide not only standardised criteria (DMA-Tg by tan δ peak;\nDSC-Tg by midpoint; TG T₅%/T_onset; char at 700/800°C) but also an explicit\nproperty-level comparison (pre- vs post-cure). This comparison clearly explains why\nCPPR-P simultaneously exhibits high E′ in the service window, a focused α-\ntransition near ~90°C, and decomposition onsets above 300°C. These differences are\nfully consistent with network formation, removal of volatiles, and confined thermal\npyrolysis, and are now properly documented in the main text (Methods section) and\nfigure captions.\n13. What tested in DMA, a printed sample or the resin? Which geometry was used?\nData presented in Figure 5e does not match with what is described in lines 555 to 559.\nOur response: We appreciate the reviewer’s careful reading. Thank you very much\nfor pointing out this obvious mistake arising from a lack of explicit detail and a\ntranscription error.\nIn DMA testing, the test sample was the printed polymer part (after DLP printing\nmoulding), not the liquid resin. DMA was performed on DLP-printed, fully cured\nspecimens. This is now stated explicitly in the Methods section.\nGeometry & fixture: The specimens used for DMA were rectangular bars in Fig.R13\ndesigned for the non-resonant flexural mode of a TA Q800 (single-cantilever fixture).\nThe STL file of the DMA bar (DMA.stl) is provided in the SI so that the geometry can\nbe reproduced exactly.\nThe inconsistency between the data described in original Fig. 5e and the text was caused\nby a transcription error when copying the testing information from the instrument. We\nhave checked and corrected this in the Methods section of the manuscript so that the\nDMA time schedule reported in the text now matches the dataset underlying Fig. 5e.\nThe corresponding raw data table, including the glass transition temperature (Tg) data\n(not plotted as a separate figure), has also been provided.\nCorrected dynamic mechanical analysis description (original lines 521–525 in the\nrevised manuscript): Dynamic mechanical analysis (DMA) was performed on a Q800\ndynamic mechanical analyser (TA Instruments) to investigate the glass transition\ntemperature, storage modulus, loss modulus, and loss factor of the samples. The\nmeasurements were performed under a nitrogen atmosphere over a temperature range\nfrom room temperature (25°C) to 500°C, at a heating rate of 10°C min⁻¹ and a frequency\nof 1 Hz.\nFig. R13 3D model of the printed sample used for DMA testing.\nTogether, these changes clarify what was tested (printed bars), which geometry/fixture\nwas used (rectangular bar, single-cantilever on Q800), and ensure that Fig. 5e and the\ndescription in the Methods section are now consistent. The Methods and SI sections\ncited above reflect these updates.\n14. In Figure 21 from SI. What is the explanation for such a high weight remaining at\n800ºC?\nOur response:Thank you for pointing this out. In Fig. R14 (SI Fig. S29), the black\ncurve corresponds to the uncured liquid CPPR resin (CPPR-L) and the red one to the\nDLP-printed, fully cured CPPR specimen (CPPR-P). This is now explicitly stated in\nthe caption. Thermogravimetry was run under nitrogen up to 800°C (Netzsch STA 449\nF3; 20 K min⁻¹), as described in the Methods section. Under this inert atmosphere, both\nmaterials form a carbonaceous char; thus, a non-zero residual mass is expected at 800°\nC. The relatively high residual weight at 800°C arises from two primary contributions:\n(1) Carbon char formation: Dehydration/aromatisation reactions of the cellulose-\nderived segments promote char formation. In addition, the covalently crosslinked\nnetwork in the printed CPPR resin further suppresses volatilisation, yielding a higher\nchar fraction than the uncured blend.\n(2) norganic ash residue: The phosphine-oxide photoinitiator (TPO) is known to\ngenerate P-oxide/phosphate residues under pyrolysis. These survive to 800°C and add\nto the apparent residual weight.\nThe high weight remaining at 800°C is not an anomaly, but the sum of: (i) carbon\nchar favoured by the cellulose-derived and crosslinked chemistries under inert\nconditions, and (ii) a small but measurable inorganic residue from the P-containing\nphotoinitiator. Switching to oxidative TG would remove the char and isolate the true\nash.\nFig. R14 TG diagram of CPPR-L and CPPR-P samples.\nWe have revised the abbreviations for materials to make the above explicit and to\nunambiguously label the curves. For clarity, we also added a note in the Methods section\nthat our TG/DSC was performed under N₂ to 800°C, which favours carbonisation (char\nformation) rather than complete oxidative burn-off. The relevant TG/DSC conditions\nand the SI fig. S29 reference are now consistent in the text.\n15. Data from GPC should also be revised. Which solvent was used for the analysis?\nWere printed samples analysed as stated in Figure 22 from SI?\nOur response: We thank the reviewer for pointing this out. We realised that the original\nGPC trace could have been affected by incomplete dissolution due to the highly\ncrosslinked nature of the CPPR-P network. Therefore, the reliability of the molecular-\nweight distribution for the soluble fraction might have been undermined. We have now\nre-optimised the GPC experiment and replaced the previous data. We repeated the GPC\nmeasurements on the soluble extractable fraction of the printed specimens using\ndeuterated DMSO (DMSO-d₆) as the mobile phase. Moreover, we have explicitly stated\nin the SI that “the analyte is the DMSO-soluble fraction extracted from the printed\nsamples, rather than the entire crosslinked network”, thereby resolving the previous\nambiguity regarding solvent selection and sample definition. We have completely\nreplaced the original traces with new data that are fully dissolved and reproducible.\nFig. R15 GPC measurements of PPR-L and AM-fabricated CPPR-P samples\nAfter DLP curing, the molecular weight of CPPR-P increases significantly compared to\nthat before curing due to polymer network formation. This increase is an important\nindicator of successful curing and enhanced mechanical properties. The updated GPC\ntraces (SI, Fig. S30) now show: The soluble fraction of the as-printed CPPR-P sample\nexhibits a unimodal distribution centred in the expected molar-mass window of the\nprepolymer/pendant chains, with a relatively narrow dispersity. This GPC evolution is\nfully consistent with the spectroscopic and thermal signatures we now report:\nFTIR/XPS/¹H NMR show new –OH/–COOH-type environments; DSC/TGA\ndemonstrate a slight Tg increase and suppression of low-temperature weight loss.\nTogether, these findings support a scenario of “mild hydrolytic scission in peripheral\ndomains + removal of plasticising sol fraction”, rather than wholesale degradation of\nthe load-bearing network.\nReviewer #2:\nGeneral Comments:\nI co-reviewed this manuscript with one of the reviewers who provided the listed reports.\nThis is part of the Nature Communications initiative to facilitate training in peer review\nand to provide appropriate recognition for Early Career Researchers who co-review\nmanuscripts.\nReviewer #3:\nGeneral Comments:\nThis paper reports a cellulose-based photopolymerizable resin (CPPR) with\nexceptional stiffness-deformability synergy and spatiotemporal shape memory\ncapabilities. A bionic structure design approach was proposed, which transforms\nbrittle photocurable 3D-printing materials into bio-inspired structures. This paper\ncarries interesting results. However, there are some concerns regarding the synthesis\nof CPPR and its characteristics.\nOur response:We greatly appreciate the reviewer’s positive comments on our\nmanuscript. We are particularly grateful for their recognition of the innovative aspects\nand the interesting results presented in our work.\n1. Lines 64-67: The authors said, “However, the potential of using cellulose as a\nprimary feedstock for directly synthesizing high-performance printable materials\nremains either unexplored or results in products with compromised mechanical and\nfunctional properties.” They did not recognize that nanocellulose has been 3D\nprinted for structural materials by esterifying nanocellulose with green crosslinkers\n(Adv. Mater. Interf. 9(16), 2200280, May 2022; ACS Appl. Nano Mater. 5, 5680-\n5687, April 4, 2022; Carbo. Pol. 320, 121197, November 2023; ACS Omega 9(22)\n23442-23450, May 2024; ACS Appl. Energy Mater. 8(1) 267–275, Jan 2025).\nOur response: We thank the reviewer for pointing out this issue. We agree that, since\n2022, several novel works on direct ink writing (DIW) 3D-printed structural materials\nbased on nanocellulose (either esterified with green crosslinkers or blended with lignin\nand related components) have been reported, achieving high mechanical strength and\ngood shape retention (Adv. Mater. Interf. 9(16), 2200280, May 2022; ACS Appl. Nano\nMater. 5, 5680–5687, April 4, 2022; Carbo. Pol. 320, 121197, November 2023; ACS\nOmega 9(22), 23442–23450, May 2024; ACS Appl. Energy Mater. 8(1), 267–275, Jan\n2025).\nWe have now added and properly cited these references in the Introduction section.\nIn addition, we have introduced a new “quantitative comparison table” (SI Table S5),\nwhich juxtaposes our work with these studies in terms of bending/compressive strength\nand modulus, printing method, crosslinking chemistry, shape-memory metrics\n(Rf/Rr/recovery time), printing resolution, and cyclic durability. These additions\nquantitatively summarise the advances in this field, while also clarifying that the above\nDIW systems primarily emphasise “structural strength/shape retention”, whereas the\npresent work focuses on the “cellulose as the main-chain source → direct DLP\nprinting → photo-crosslinked networks imparting shape-memory and anti-fatigue\nproperties”. Therefore, the two lines of research address different but complementary\nquestions and technical routes. The corresponding revisions have been incorporated\ninto the Introduction section and the Related Work subsection of the revised manuscript.\nClarification and revision for original lines 64–67: Previous studies on 3D printing\nof biomass and its derivatives have demonstrated that nanocellulose can be esterified\nwith green small molecules (e.g., citric acid) or blended with lignin and related\ncomponents, thereby enabling DIW printing of high-solids-content (≥25 wt%)\nstructural parts with high strength and good shape retention (bending strength of 83–\nas the primary carbon source to directly synthesise photocurable resins suitable for DLP\nprinting (rather than aqueous paste-type DIW). While maintaining high mechanical\nperformance, these resins endow the printed structures with pronounced shape-memory\nbehaviour and multi-cycle anti-fatigue capability. This approach addresses the\nlimitations of existing DIW structural materials by making the final product\n“photopatternable, rapidly formable, and capable of programmable deformation”.\nTable R1 Comparison of the CPPR resin system developed in this study with previously reported\n3D printing of cellulose-based materials.\nComparison Ref1 Ref2 Ref3 Ref4 Ref5 Ref6 This work\nwork\nTypes\nPrinting DIW → DIW → DIW→ DIW DIW → DIW → Highly\nmethod 140 ℃ freeze- clean → clean cleanroom customised, high-\n/20 min drying/slo room control room drying/fil precision DLP\nvacuum w drying in drying led drying + m forming printing\nesterifica clean room (no drying post\ntion resin mouldi curing\ncuring infusio ng\nn)\nKey points of ≈ 25.50 wt% 25.46 25 25.45 Polycarbo Modified cellulose\ncrosslinking/c 25.94wt NC; 2.50– wt% wt% wt% nate as the main\nuring and % NC; 10 wt% NC + grade NC+alkal substrate+ reactive monomer\nformulation CA is a PVA; 15 wt% NC; A i lignin; 2-8wt% → photo\ngreen Improved PVA; woode LG is NC crosslinking\ncrosslink interlayer Resin n base used as a\ning adhesion free is used “nano\nagent; infusio to filler/adhe\nEmphasi n acceler sion aid”\ns on ate\ninterlaye bottom\r bonding\nRepresenting Bending Bending Bendin Bendin Bending Tensile Compressive\nmechanical strength strength g g strength strength strength ≈ 115.4\nproperties (at 82.78 ± 120 ± 2 strengt strengt 102.93 ± 139.92 ± MPa; Tensile\nroom 2.79 MPa; h 94.78 h 149 0.96 MPa; 5.3 MPa; strength ≈ 27-\ntemperature) MPa; Bending ± 3.18 ± 2 Bending Young's 28 MPa (see\nBending modulus 15 MPa; MPa; modulus modulus manuscript)\nmodulus ± 0.1 GPa Modul Bendin 9.05 ± 5.74 ±\n6.97 ± us 9.00 g 0.07 GPa 0.32 GPa;\n0.38 GPa ± 0.27 modul Fracture\nGPa us 15 ± elongation\n0.8 6.13 ±\nGPa 0.15%\nShape Not Not Not Not Not Not Rf:≈60.54%; Rr:\nmemory reported reported reporte reporte reported reported 94.54%; Tr: ≈\nindex d d 60s\n(Rf/Rr/time)\nRepresenting No No No No Small No Adjustable and\nresolution & volume customisable\nloop shrinkage printing\nfluctuatio resolution and\nns multi-cycle fatigue\nresistance (see\nmanuscript)\nRemarks Green Improved Slow The The Potential Different from the\ncross- interlayer drying author addition of NC DIW structural\nlinking, adhesion curing refers of lignin membrane materials listed\nhigh and for to it as fillers structural above in terms of\nmechani environme shrinka one of significan componen technical path and\ncal ntally ge the tly ts in target function:\npropertie friendly crack highest improves energy emphasising\ns, and structure prevent strengt interlayer devices/te “photolithograph\nsignifica ion hs of adhesion nsile y+shape memory”\nnt DIW and conditions\nrepeatabi extrud repeatabil\nlity ed NC ity\ncurrent\nly\navailab\nle\nNote:\nRef1 :High-solids-content nanocellulose (NC)+citric acid (CA) esterification (Adv. Mater.\nInterf. 9(16), 2200280, May 2022),\nRef2 :high-solids-content nanocellulose+PVA adhesion aid (ACS Appl. Nano Mater. 5,\n5680-5687, April 4, 2022),\nRef3 :High-solids-content nanocellulose+PVA clean room “green composite” (Polymers\n15, 669, Latif et al., 2023),\nRef4 :High-solids-content nanocellulose+substrate engineering (wood substrate) (Carbo.\nPol. 320, 121197, November 2023),\nRef5: Nanocellulose/Lignin Blend (LG-NC) (ACS Omega 9(22) 23442-23450, May\n2024),\nRef6 :3D printing of high-strength nanocellulose film (energy device) (ACS Appl. Energy\nMater. 8(1) 267–275, Jan 2025),\nOur work: Cellulose-based photopolymerisation DLP printing resin. Direct\nextrusion (DIW) extrusion, Digital Light Processing (DLP).\nThe Table above incorporates all studies explicitly mentioned by the reviewer and\nprovides concrete experimental values for direct cross-checking. Most DIW-based\nworks do not report shape-memory performance, whereas in our study, the shape-\nmemory effect arises from the programmable recovery of a photo-crosslinked network.\nAccordingly, we have revised and clarified our discussion and positioning of the related\nwork as follows:\n(1) Different material targets and processing routes: The DIW–NC systems use\nwater-based, high-solids-content pastes as inks. Citric-acid esterification or lignin/PVA\nblending is employed to improve interlayer adhesion and shape fidelity, and the\nstructures are formed via direct extrusion followed by post-curing. In contrast, our work\nuses cellulose as the main-chain carbon source, chemically modifying it to obtain a low-\nviscosity photocurable resin compatible with DLP printing. This approach successfully\naddresses the “photolithographic processability + high mechanical performance +\nshape-memory capability” trilemma.\n(2) Different performance emphases: DIW–NC systems excel in static flexural\nstrength and modulus (up to ≈149 MPa and ≈15 GPa, respectively), but they do not\nprovide high-precision customisation or rapid forming capability, nor do they typically\nreport shape-memory-related metrics. Our study, not only delivers high strength (e.g.,\ncompressive strength ≈115 MPa) but also offers a full shape-memory profile,\nincluding Rf/Rr, recovery time, and cyclic durability.\n(3) Complementary scalability and application scenarios: DIW–NC systems are\nwell suited for large-scale structures and biomedical scaffolds. In contrast, the DLP–\nCPPR system developed in this work is specifically tailored for high-resolution,\ncomplex-topology, and programmable deformation devices, e.g., impact-absorbing\nenergy dissipators and integrated soft–hard structures.\n2. The synthesis of ECHMCC, UC-CPPR, and CPPR: The authors did not explain\nclearly how to synthesize them step by step in Methods and Supporting Information.\nMCC is crystalline cellulose, and ECHMCC seems an amorphous cellulose, as\nshown in SI Figure 13. It seems that the authors dissolved MCC and performed\nepoxidation. Once it is true, then the cellulose solvent could influence all of\nproducts. The authors need to explain it.\nOur response: Thank you very much for your suggestion. Upon review, we realised\nthat key methodological details were indeed missing, preventing a clear and\nunambiguous description of the synthetic route for obtaining the photocurable resin.\nWe have now provided sufficient detail to ensure reproducibility of the reaction and\nhave incorporated this information into the Methods section of the revised manuscript\n(lines 439–477). We are grateful to you for pointing out this critical omission.\nSynthesis – Step 1 the prepared process of MCC epichlorohydrin.\nThe reaction shown in Fig. R1(Fig. S13 of the SI) corresponds to Step 1 of the synthesis.\nFirst, an epoxide ring-opening reaction occurs between the cellulose chains and\nepichlorohydrin. Briefly, 2 g of pretreated microcrystalline cellulose (MCC) was\ninitially allowed to swell and uniformly dispersed in 70 mL of DMSO and maintained\nat 50°C in a water bath until a homogeneous suspension was obtained. Subsequently,\nepichlorohydrin (40 mL) was placed in a dropping funnel and added dropwise at a rate\nof 10 mL h⁻¹. Then, 15 mL of 30 wt% aqueous NaOH solution was added dropwise\nover 30–45 min using a dropping funnel. The mixture was then heated to 80–85°C and\nallowed to react for a further 4 h. After cooling the reaction system to room temperature,\nthe functionalised MCC precursor was obtained. Under alkaline conditions at 80°C, the\nepoxide group of epichlorohydrin underwent a ring-opening reaction to generate\nreactive sites, at which point the primary hydroxyl group at the C6 position of cellulose\nreacted with it. The resulting product is named as MCC-E.\nFig. R1 Epoxide ring-opening reaction between cellulose molecules and epichlorohydrin.\nSynthesis – Step 2 the synthetic of Cellulose-based photopolymerisable resin\n(CPPR) precursor .\nThe reaction depicted in Fig. R2(Fig. 14 of the SI) corresponds to Step 2 of the\nsynthesis. Based on the precursor obtained in Step 1, free-radical photoreactive groups\nwere grafted onto the cellulose backbone. The product from Step 1 was transferred into\na 500 mL round-bottom flask and 0.5 wt% methanesulfonic acid (CH₃SO₃H) was used\nas a catalyst. Subsequently, 50 wt% hydroxyethyl methacrylate(HEMA) (C₆H₁₀O₃) was\nadded to introduce the free-radical photoreactive grafting groups, and the mixture was\nstirred at 70°C in a water bath for 6 h. After reaction completion, the system was cooled\nto 50°C and maintained for a further 4 h to ensure complete conversion. The resulting\nproduct is Cellulose-based photopolymerisable resin (CPPR) precursor used for DLP\nadditive manufacturing.\nFig. R2 Graft-free radical photosensitive reactive groups.\nSynthesis – Step 3 the synthetic of Cellulose-based photocurable print resin liquid\n(CPPR-L).\nThe reaction exhibited in Fig. R3(Fig. 15 of the SI) corresponds to Step 3, which details\nthe photo-initiated free-radical polymerisation of the CPPR resin. First, 150 mL of the\nCPPR resin monomer prepared in Step 2 was transferred into a 500 mL round-bottom\nflask, followed by the addition of 15 mL of ethylene glycol dimethacrylate\n(EGDMA) as a reactive co-monomer for the subsequent free-radical polymerisation.\nThe mixture was stirred at 50°C until complete dissolution. Next, the temperature\nwas lowered to 30°C (to prevent premature partial polymerisation), and 40 wt%\nacrylamide (C₃H₅NO) was introduced as a crosslinker. The reaction was allowed to\nproceed under stirring for 30 min at 30 °C. Subsequently, 0.1 wt% N,N′-\nmethylenebisacrylamide (MBA) was introduced, and stirring continued for another 30 min.\nFinally, 0.5 wt% TPO was added as the photoinitiator, and stirring was continued until a\nhomogeneous Cellulose-based photocurable print resin liquid (CPPR-L) capable of\nundergoing UV-induced free-radical polymerization was obtained. The CPPR-L2 and\nCPPR-L3 were fabricated according to the different content of CPPR and acrylamide.\nHEMA-PR refers photocurable print resin only with HEMA. NE-CPPR refers CPPR\nwithout MCC epichlorohydrin step.\nFig.R3 DLP-based UV curing via free radical polymerisation and crosslinking.\nRegarding the issue you raised in your revision comments concerning MCC dissolution\nand the change in crystallinity (SI Fig. S23), we would like to thank you for pointing\nthis out, as it helps make our manuscript more scientifically rigorous and easier to\nfollow.\nFirst, we did not dissolve MCC in a cellulose-dissolving medium (such as DMAc/LiCl,\nionic liquids, or NaOH/urea). Step 1 is explicitly conducted in a heterogeneous\nalkaline system at 80 °C, where MCC is in a swollen/dispersed state. ECH reacts with\nthe C6–OH groups of MCC via epoxide ring-opening etherification and results in a\nsmall degree of interchain bridging; it is not a dissolution process mediated by “true\ncellulose solvents”.\nThe supporting data and analytical evidence confirm this:\n(1) The process description in SI Fig. S13 clearly states “alkaline conditions at 80°\nC, with C6 participating in the reaction”, which indicates that ECH reacts mainly\nwith primary hydroxyls at the C6 position to form ether linkages and occasional\ninterchain bridges.\n(2) Fig. R4 (SI Fig. S22) FTIR shows the appearance/intensification of C–O–C bands\nat 1120–1160 cm⁻¹.\nFig. R4 FTIR spectra of microcrystalline cellulose (MCC) raw materials and epichlorohydrin-\nmodified cellulose molecules (MCC-E) via ring-opening epoxidation (Synthesis - Step 1).\n(3) Fig. R5 (SI Fig. S20) ¹H NMR reveals a new signal region at 3.6–4.2 ppm.\nFig. R5 1H NMR spectra of MCC molecular raw material and epichlorohydrin-modified\ncellulose molecules via ring-opening epoxidation (Synthesis - Step 1).\n(4) Fig. R6 (SI Fig. S23) XRD demonstrates only a decrease in the\nintensity/crystallinity of the cellulose I (002) reflection, without conversion to\ncellulose II or the presence of a fully amorphous halo.\nFig. R6 XRD patterns of MCC raw materials and epichlorohydrin-modified cellulose\nderivatives via ring-opening epoxidation (Synthesis - Step 1).\nTaken together, these features are indicative of substitution-induced disorder, rather\nthan a dissolution–regeneration pathway of cellulose. The XRD changes are consistent\nwith the chemical “anchors” observed via FTIR/NMR and can be attributed to\netherification substitution + local crosslinking that disrupts the hydrogen-bond network,\nrather than to any solvent-induced regeneration process.\nFurthermore, after Step 2 (HEMA grafting), the crystalline form and overall\ncrystallinity of the material remain essentially unchanged (SI Fig. S25). This further\nsupports that the “apparent amorphisation” originates from chemical substitution and\nhydrogen-bond disruption, and that no dissolution–regeneration of cellulose has\noccurred.\nIn Step 3, the acrylamide network introduced by photocuring may induce new ordered\npeaks in the XRD patterns of the DLP-printed samples (SI Fig. S12). This reflects an\nincrease in order associated with the final covalent network, which is not contradictory\nto the “local disordering” observed in the first two steps. Instead, it represents a new\norder parameter that emerges only following DLP printing and curing.\nAs regards the concern that “the solvent may affect all products”, we explicitly state in\nthe Methods section that no cellulose-dissolving solvent system was utilised in the\nsynthetic procedures. DMSO-d₆ was employed only as a characterisation solvent for\nNMR measurements (on separately prepared samples) and was not involved in any\nother synthetic pathways.\n3. The authors should carefully use the acronyms by denoting full names, for example,\nECHMCC.\nOur response: Thank you for your suggestion. We acknowledge the need for clear and\nconsistent abbreviation usage. We have re-standardised the nomenclature using a more\nsystematic and scientifically sound scheme to improve clarity and reproducibility. In\nparticular, we retain CPPR as the main system name and harmonised the other\nabbreviations to the format “[chemical motif]-PR”, avoiding overly long stacked\nabbreviations. We also introduced suffixes (L/P) to indicate the physical state of the\nmaterial. This yields a coherent and readable unified naming/definition scheme across\nthe entire manuscript.\nNow, HMPR is denoted as HEMA-PR (a cellulose-free photocurable resin containing\nonly HEMA) and NE-CPPR is explicitly defined as the non-epoxidised variant of CPPR\n(without the ECH step). Where appropriate, we have added the state suffixes: CPPR-L\n(uncured liquid CPPR resin feedstock) and CPPR-P (DLP-printed CPPR specimens).\nMoreover, ECHMCC is now called MCC-E, referring to MCC molecules grafted via\nECH epoxide ring-opening etherification.\nAll abbreviations are introduced as “full name + abbreviation” at their first appearance\nin the main text and are subsequently used in abbreviated form only. In addition, the\nunified abbreviations are summarised in a dedicated “Abbreviations” table in the SI,\nand the same terminology is consistently used throughout the text, figures, and\ncaptions.\nTable. R2 Summary Table of Abbreviations.\nAbbreviation Abbreviation Full name\nNew name Old name\nCPPR CPPR Cellulose-based photopolymerisable resin precursor\nCPPR-L UC-CPPR Uncured CPPR resin feedstock\nCPPR-P (None) DLP-printed CPPR specimens\nHEMA-PR HMPR Cellulose-free photocurable resin containing only HEMA\nNE-CPPR NE-CPPR Non-epoxidised variant of CPPR (without the ECH step)\nMCC-E ECHMCC MCC molecules grafted via ECH epoxide ring-opening etherification\n4. The mechanical properties of CPPR (compressive strength of 115.42 MPa and\nstiffness of 1404.16 MPa) are much lower than the nanocellulose 3D printed results.\nThe authors need to compare their results with previously reported ones.\nOur response: We thank the reviewer for once again raising the issue of how our work\nrelates to and compares with previously reported 3D-printing results based on\nnanocellulose. As discussed in our response to your earlier Comment #1, we fully\nacknowledge that multiple studies since 2022 have reported direct ink writing (DIW)\n3D-printed structural materials based on nanocellulose, achieving high strength and\ngood shape fidelity (16-20).\nIn this revision, we have addressed this concern by adding a “quantitative comparison\ntable” (Table. R1/SI Table S5 ) that places our work side-by-side with these studies\nalong several dimensions, including material system, printing/forming method,\nmechanical strength, crosslinking chemistry, shape-memory metrics\n(Rf/Rr/recovery time), printing resolution, and cyclic durability. These comparisons\nquantitatively illustrate the progress in this field, while also clarifying that the above\nDIW systems primarily emphasise “structural strength/shape retention”, whereas the\npresent work focuses on “cellulose as the main-chain source → direct DLP\nprinting → photo-crosslinked networks imparting shape-memory and anti-fatigue\nproperties”. Therefore, the two lines of research address different but complementary\nscientific questions and technical routes. The corresponding revisions have been\nincorporated into the Introduction section and the Related Work subsection of the revised manuscript.\nBy comparing our research results with previously reported 3D printing results of\nnanocellulose, we can draw a systematic, specific, and comprehensive comparison\nconclusion. Most DIW-based works do not report shape-memory performance, whereas\nin our study, the shape-memory effect arises from the programmable recovery of a\nphoto-crosslinked network. Accordingly, we have revised and clarified our discussion\nand positioning of the related work as follows:\n(1) Different material targets and processing routes: The DIW–NC systems use\nwater-based, high-solids-content pastes as inks. Citric-acid esterification or lignin/PVA\nblending is employed to improve interlayer adhesion and shape fidelity, and the\nstructures are formed via direct extrusion followed by post-curing. In contrast, our work\nuses cellulose as the main-chain carbon source, chemically modifying it to obtain a low-\nviscosity photocurable resin compatible with DLP printing. This approach successfully\naddresses the “photolithographic processability + high mechanical performance +\nshape-memory capability” trilemma.\n(2) Different performance emphases: DIW–NC systems excel in static flexural\nstrength and modulus (up to ≈149 MPa and ≈15 GPa, respectively), but they do not\nprovide high-precision customisation or rapid forming capability, nor do they typically\nreport shape-memory-related metrics. Our study, not only delivers high strength (e.g.,\ncompressive strength ≈115 MPa) but also offers a full shape-memory profile\nincluding Rf/Rr, recovery time, and cyclic durability.\n(3) Complementary scalability and application scenarios. DIW–NC systems are\nwell suited for large-scale structures and biomedical scaffolds. In contrast, the DLP–\nCPPR resin system developed in this work is specifically tailored for high-resolution,\ncomplex-topology, and programmable deformation devices, e.g., impact-absorbing\nenergy dissipators and integrated soft–hard structures.\n5. Lines 345-346: “Moreover, the cyclic compression tests confirmed the excellent\nshape memory 345 recovery function of the material (Fig. 5c).” Fig. 5c shows\nnothing but pseudo-elastic (or super-elastic) behavior of CPPR material. Once\nCPPR has shape memory effect, then its quasi-plastic behavior (residual strain)\nneeds to be shown. Otherwise, it may not be appropriate that CPPR has shape\nmemory effect.\nOur response: We appreciate the reviewer’s observation and agree that the original\nFig. 5c demonstrated a thermal pseudo-elastic (superelastic-like) recovery under cyclic\ncompression at room temperature, which alone is insufficient to evidence thermally\ntriggered shape-memory effect (SME). To definitely address this concern, we have\nperformed additional thermally triggered shape memory experiments, and the results\nare presented in the Supplementary Materials. In these new tests, the material was\nprogrammed into a temporary shape via tensile loading and then heated to 100°C to\ntrigger shape recovery (Table.R3). The shape memory performance is now\nquantitatively confirmed by a high shape fixity ratio (Rf), a high shape recovery ratio\n(Rr), and a rapid recovery time (Tr). All these metrics demonstrate that the deformed\nshape is fully fixed at room temperature and almost completely recovered upon heating.\nWe have also included a video in the SI showing the sample programming, shape\nfixation at room temperature, and subsequent recovery upon heating, providing clear\nvisual evidence of the SME. All in all, we have (i) revised the text around Fig. 5c to\ndescribe it strictly as cyclic superelastic-like recovery, and (ii) added a dedicated SME\nprotocol, dataset, and video (Supplementary Movie S5) showing programming–\nfixing–recovery with the required quantitative metrics.\nTable R3 Shape Memory Test.\nSample Initial Final Applied strain Fixed Shape Shape ≥ 90% Trigger/switch\nname length residual (test gauge strain fixation recovery Recovery temperature\n(L0) plastic length=50 rate (Rf) rate (Rr) time (Ts)\nstrain mm) required\n(Tr)\nn 1 7.00 cm 2% 41.82% 24% 57.39% 91.67% ≈70 s 100℃\nn 2 7.00 cm 1% 56.46% 38% 67.30% 97.37% ≈60 s 100℃\nn 3 7.00 cm 2% 48.50% 28% 57.73% 92.86% ≈50 s 100℃\nn 4 7.00 cm 2% 54.90% 34% 61.93% 94.12% ≈60 s 100℃\nn 5 7.00 cm 1% 51.42% 30% 58.34% 96.67% ≈60 s 100℃\nResults: Across five samples and programmed strains, we obtained Rf = 60.5% ±\n4.6%, Rr = 94.5% ± 2.5%, and t_r ≈ 60–70 s at 100°C. The table also lists the\nresidual strain after recovery for each specimen, directly addressing the reviewer’s\nrequest for quasi-plastic behaviour. No sample fractured during programming or\nrecovery (see Table S1 “Shape-memory tests” and Supplementary Movie S5).\nThe moderate Rf (~60%) reflects the relatively dense covalent network (beneficial for\nload-bearing) and the presence of reversible H-bonding. Nevertheless, an Rr ≳ 94%\nwith minute-scale recovery confirms thermally triggered SME. We have retained Fig.\n5c to document room-temperature super-elastic-like cyclic recovery, but now we make\nclear that definitive SME evidence comes from the thermally programmed tests\n(Supplementary Table S2 +Movie S5), not from Fig. 5c.\nFig. R4 SME demonstration.\nIn addition, we have revised the description of Fig. 5c in the main manuscript to clarify\nthat it represents a pseudo-elastic mechanical response (superelastic behaviour) and not\na shape memory cycle. All SME results, including the Rf, Rr, and Tr values and the\nvideo demonstration, have now been moved to a dedicated section in the Supplementary\nMaterials. This separation ensures there is no confusion between the pseudo-elastic\nbehaviour highlighted in Fig. 5c and the genuine SME, which is explicitly demonstrated\nin the supplemental data.\nWe believe these revisions fully resolve the reviewer’s concern by clearly proving the\nmaterial’s SME while properly distinguishing this behaviour from pseudo-elastic\nrecovery. The above changes are implemented in the revision: the Methods section now\nincludes the full SME schedule, statistics, and definitions, and the SI provides the raw\nspreadsheets and the demonstration video link.\nReviewer #4:\nGeneral Comments:\nThe manuscript reports a cellulose-based photo-polymerizable resin for 3D printing\nthat exhibits very promising structural integrity, stress dissipation, and shape-\nmemory behavior. The topic is of interest and the experimental work is substantial.\nOverall, I believe the manuscript could be suitable for publication in Nature\nCommunications after revision. Blow are my detailed comments.\nOur response: We greatly appreciate the reviewer’s positive comments on our\nmanuscript. We are particularly grateful for the recognition of the innovative and\ncontent aspects of our work. We believe the revisions performed address all comments\nthoroughly.\n1. The authors should more clearly place this work in the context of existing 3D-\nprinted shape-memory resins. A dedicated comparison (e.g., table + discussion) to\nrecent reports is required, highlighting the most relevant metrics such as recovery\ntime, recovery ratio, mechanical properties, switching temperature, cycle life, and\nprinting resolution. This will help demonstrate the degree of advancement in a\nquantitative manner.\nOur response: We thank the reviewer for this constructive suggestion. This addition\nallows us to place the present work more clearly in the context of existing 3D-printed\nshape-memory resins and quantitatively highlight the extent of our advances.\nIn accordance with your suggestion, a dedicated comparison Table. R1 (SI Table S6) has\nbeen added, which summarises and compares representative biomass-based and -\nderived 3D-printed shape-memory resin systems reported since 2022. The table\nexplicitly lists the following most relevant metrics: material system, bio-based\nfeedstock, printing method, shape-memory metrics (Rf/Rr/recovery time),\nrepresentative mechanical strength, printing resolution/parameters, cyclic durability,\nand switching trigger (e.g., temperature). Furthermore, we have analysed and discussed\nthese comparisons in the revised support information, and the corresponding table and\ndata have been incorporated into the SI as Table S6. For your convenience, the contents\nof this table are reproduced below:\nTable R1 Comparison of biomass-based and -derived shape memory resins for 3D\nprinting.\nP ol y m er. 3 0 7, 1 2 7 2 5 2, A v a 2 0 2 4 M a cr o m ol. R a pi d C o m m u n. 4 6, 2 4 0 0 6 6 1, A mi n 2 0 2 5 A d v. M at er. I nt erf. 9( 1 6), 2 2 0 0 2 8 0, M a y 2 0 2 2 N - at ur e. 6 2 9, 1 0 6 9 1 2 0 0 7 2 4 4, M a c h a d o N at ur e C o m m u ni c ati o ns. 1 4, 5 5 1 9, Yu e 2 0 2 3 A F M. 3 5, 2 4 1 4 1 2 9, G h os al 2 0 2 5 S ci e n c e A d v a n c es. 1 0, 4 3 8 7, Li 2 0 2 4 T his w o r k\nal\nm\nP ri nti n g m o ul di n\ng\nm et h o d F D M/ F F\nF\nF D M D →\nt\nh\nI\ne\nW\nr\ne st erifi c\nati\no\nn\nD L P/ V P\nP\ng- D L P D L P D L P D L P\nM e c h a ni c al p e rf o r m a n c e ( v r a e l p u r e e ) s e nt ati v e Te nsil e str e n gt h: 4 0. 8 M P a; M ≈ M 8 o P 0 d a 0 u l us U T S 3 5. 9 M P a ( 1 0 % F ₃ O₄ R ) e ; e sili e n c e e n h a n c e m e nt B e n di n g str e n gt h 8 2. 7 8 ± 2. 7 9 M P a; M o d ul us 6. 9 7 ± 0 . 3 8 G P a T ≈ M e 1 P n 7 a s i ; l e str e n gt h M ≈ M 4 o P 7 d a 8 u l us T i ≈ M l e 1 e P n 0 s a s t ; r e n gt h M ≈ a x 3 i m u m m o d ul us M P a T - 3 2 e n sil e str e n gt h: 1 5 M P a; M a xi m u m m o d ul us ≈ G 1 P . a 0 6 C o m p r essi v e st r e n gt h 1 1 5. 4 2 M P a; M o d ul us 1. 4 0 4 G P a; Te nsil e s t r e n gt h 2 5. 1 6 M P a\nS h a p e m e m o r y i n d e x ( Rf/ R r/ti m e) Rf: N ot r e p ort e d; Rr: 9 6 % ( P L A), 9 2 % ＋ ( D P C L P A ) 9 ; 0 T / r P : B N S o 1 t 0 r e p ort e d R ≈ - 9 ( H 7 9 f: % 6 e a N t o & t r e p ort e d; Rr: M a g n eti c); Tr: Aft er f ull y tri g g eri n g, r - 5 - e a c h s > ( 1 9 5 0 % wit hi n 3 2 0 wt % F e 3 O 4) N o n e N o n e R - 9 5 f: % 8 ; 0 / Rr & Tr: T h e vi d e o e x a m pl e d e m o nstr at es t h e r e c o v er y pr o c ess wit h o ut p i f r i o e d v i d d a i n t a g o u n n ti m e or r at e Rf > 7 0 % ( v ari es wit h pr o gr a m mi n g); Rr & Tr: C o m pl et e t h er m al tri g g er r e c o v er y w - 1 0 i 0 t h i n s 4 ( 0 e x a m pl e o p er ati n g c o n diti o n) N o n e R ≈ R ≈ s 6 6 f r 0 0 : : . 9 5 4 4 . % 5 4 ; %; Tr:\nP ri nti n g r es ol uti o n/ p a r a\nm et e rs\nN ot r e p ort e d a n\nd u n a bl e t\no\na dj ust N o n e N o n e 3 0 u m pi x el si z\ne; C a n pri\nnt\n1 0 0 u m w all; 5 0\nu m/l a y er\n5 m 0 l μ e v el N o n e N o n e Mi ni m u m f e at\nu r e ~ 5 µ\nm;\n5 0 µ m/ L a yl a; 8\ns/l a y e r\nC y cl e lif e N o n e N o n e N o n e N o n e 4 0 c y cl es of d ef or m ati o\nn\na n d r e c o v er y T h er e is a l o o p i n t h\ne\ndi a gr a m, b ut n o u nif or\nm\nfr e q u e n c y/r et e nti o n r at e\nis\np r o vi d e d M - c y u cl l e ti st a bilit y St a bl e t h r o u g h m ulti pl\ne\nc o m p r essi o n a n\nd\ns t r et c hi n g c y cl es\nof\nn\ng\nn\ng\n<\n0 of\nS wit c h (t e m p e r at u r e) 7 w 0 a ℃ t er b at h > T _ g; C o m bi n e d eff e ct h e at a n d alt er n ati m a g n eti c fi el d N ot r e p ort e d N ot r e p ort e d C st o ar n t v i ersi o n t ≈ e m 6 2 p / e 4 r 2 a / t ur e: Tc ( t hr e e s yst e ms) N ot e x pli citl y st at e d S wit c h t e m p er at ur e ~ 7 5 ℃ 1 0 0 ℃\nNote: PLA/PBS Biobased blending (FDM; Polymer. 307, 127252, Ava 2024), PLA-\nPBAT/Fe₃O₄ (FDM; Hot/magnetic dual trigger SME) (Macromol. Rapid Commun. 46,\n2400661, Amin 2025), High-content nanocellulose (CA green esterification\ncrosslinking, DIW) (Adv. Mater. Interf. 9(16), 2200280, May 2022), Recyclable\n\"thiolactone\" photoresist (Nature. 629,1069-1074, Machado 2024), Gray scale DLP\ncold programming deformation structure (SMP system, non-biobased) (Nature\nCommunications. 14,5519, Yue 2023), Olive oil-based 4D photosensitive resin (AFM.\n35, 2414129, Ghosal 2025), High toughness shape memory DLP structure (reference\ncontrol, non-biobased) (Science Advances. 10, 4387, Li 2024), This work: Additive\nmanufacturing of cellulose-based photopolymerizable resin with high strength\nand shape-memory. Fused Fiber Manufacturing (FDM/FFF) technology, Ink direct\nextrusion (DIW) extrusion, 3D printing based on grayscale digital light processing (g-\nDLP), Digital Light Processing (DLP). R_f = shape fixity ratio; R_r = shape recovery\nratio; T_r = time required to reach ≥90% recovery; T_sw = triggering/switching\ntemperature (T_g or T_trans); Resolution = reported as the minimum feature size or\npixel/layer thickness available in the cited literature.\nBy placing our work more clearly in the context of existing 3D-printed shape-memory\nresins and comparing it with previously reported 3D-printed shape-memory systems,\nwe can provide a clear, specific, and integrated comparison of the research content and\nconclusions, allowing us to quantitatively demonstrate the extent of the advances\nachieved in this study:\n(1) Comparison of “recovery rate” with FDM (thermally/magnetically triggered)\nsystems: FDM-printed PLA-based SMPs can achieve second-scale recovery under\nexternal thermal or magnetic stimulation. For instance, PLA–PBAT/Fe₃O₄\nnanocomposites reach >90% recovery within 3–4 s in hot-water-triggered tests (15–20 wt% Fe₃O₄),\nachieving ~96–97% R within 58 s under a magnetic field (depending on composition).\nr\nIn contrast, the CPPR resin system developed in this work rebounds spontaneously at\nroom temperature without any external field after an ultrahigh compressive strain of\n75%, restoring both its shape and load-bearing function (strength) within 4–5 min.\nThis “high-load, room-temperature self-recovery” condition is not directly comparable to\nFDM systems, which are mostly triggered above their T . Accordingly, the manuscript\ng\nemphasises the fundamental differences in load level and environmental boundary\nconditions, highlighting the engineering significance of our stress-release-driven self-\nrecovery without external heating.\n(2) Comparison of the “mechanical ceiling” with DIW green-crosslinked\nnanocellulose structural components (SI Table 5): DIW, high-solids-content\nnanocellulose parts employing citric acid (CA) green crosslinking followed by\nesterification can reach a flexural strength and modulus of 82.78 MPa and 6.97 GPa\n(ADMI 2022), respectively, while more recent DIW lignin/nanocellulose composites\nachieve 102.93 MPa/9.05 GPa (ACS Omega 2024). These studies are primarily\npositioned as structural materials (high strength and shape fidelity) and do not\nsystematically report SME metrics. In contrast, the proposed CPPR resin system\nachieves a compressive strength of 115.42 MPa within a photocured network while\nsimultaneously combining high strength, toughness, and recoverability. By using DLP\nprinting, we obtain a single resin system that provides both high mechanical strength\nand complex shape-memory responses, representing an advancement in coupled\nperformance rather than a mere competition in strength or stiffness.\n(3) Comparison of manufacturability/resolution with other sustainable\nphotoresins: The thiolactone-based circular photoresin reported in Nature (2024)\ndemonstrates high-fidelity printing with 30 µm pixels, 50 µm layer thickness, and 100\nµm wall thickness, demonstrating that high resolution and cross-platform\nmanufacturability can be achieved via sustainable chemistry routes. In this work, our\ncustomised DLP setup achieves a minimum feature size on the order of ~5 µm,\ntogether with efficient fabrication at a conventional 50 µm/layer and 8 s/layer. Thus,\nin terms of resolution, our system is on the same order, or even finer in terms of minimum feature\nsize, than these state-of-the-art formulations reported in top-tier journals.\n(4) Recovery mode and temperature window: The distinctive feature of the proposed\nCPPR resin system is the coexistence of: (i) rapid stress-release-driven rebound at room\ntemperature, (ii) high load-bearing capacity and stiffness (compressive strength ≈\n115.42 MPa; E_tensile ≈1.40 GPa), (iii) reproducible printing resolution and process\nparameters (50 μm, 8 s per layer), and (iv) stability in aqueous environments. This\nprofile is complementary to most academically reported thermally triggered SMPs or\nlow-modulus soft networks, e.g., cardanol-based networks, E ≈ 0.2–2 MPa. Our\nCPPR-P maintains a relatively high storage modulus (DMA) in the room-to-medium\ntemperature range (0–100°C), with a Tg of ~90°C, indicating better suitability for\nstructural applications at elevated service temperatures. The results indicate that, under\na “heavy-load, thick-section” condition of 75% compressive strain, the samples can\nfully recover their overall shape within 4–5 min, which is an appropriate recovery\ntimescale for thick, load-bearing components.\nThe olive-oil-based system reported in AFM 2025 exhibits a Tg of around 20–25°C\n(higher Tg₂) and achieves recovery within 40–100 s. It offers advantages in rapid\nresponse for thinner parts in a mild temperature window, rendering it suitable for\nconstrained conditions such as biomedical use. The work published in Nat. Commun.\n2023 provides a cold-programming strategy with multi-stage activatable transitions (Tc\n= 62/42/<0°C), highlighting cutting-edge capabilities in programming freedom and\nmanufacturability of complex architectures. In this context, the proposed CPPR resin\nsystem differs from previous studies in both the application domain and response\nregime and is complementary to them.\n(5) Mechanical benchmarks: In this work, a compressive strength and modulus of\n115.42 MPa and 1.404 GPa, respectively, represent a rare combination of high load-\nbearing capacity and recoverability among bio-based SMPs. For instance, in other\nstudies: the lipoate system reported in Nat. 2024 follows a circular reprinting route and\ndemonstrates a thermal/mechanical window comparable to commercial products, but\ndoes not primarily target SMP metrics; the work published in Sci. Adv. 2024 presents\nextreme stretchability (>1400%), but is not bio-based.\n(6) Printing resolution/complexity (precision): In this work, we have achieved a\nprocess resolution of 5 μm under DLP conditions, facilitated an integrated\ndemonstration of design–fabrication–performance. This resolution contrasts favourably\nwith the highest precision reported in comparative studies (e.g., Nat. 2024), which\ninvolved a systematic evaluation of dimensional deviation and z-direction cure depth\nat a pixel size of 30 μm. This capability highlights that our system is exceptionally well-\nsuited for highly customised, high-precision structural printing. It further suggests that\nthe established pixel/layer-thickness–to–dimensional-accuracy data from those prior\nworks can be leveraged for benchmarking our own high-resolution prints.\nFDM relies predominantly on thermal or magnetic triggering for rapid (second-scale)\nrecovery, but its printing resolution and ability to form complex topologies are\ninherently constrained by nozzle geometry and the layer-by-layer deposition path. DIW\nsystems, while excelling in strength and shape fidelity due to green-crosslinked\nnanocellulose, rarely report key shape-memory effect (SME) metrics. DLP/SLA offer\nadvantages in resolution, complex microstructures, and scalability. Our work\ndemonstrates that, even when biomass is utilised as the primary feedstock, it is still\npossible to achieve strength–shape-memory coupled performance on the same order as\nestablished engineering thermosets.\nFrom the perspective of matching materials, structures, and service conditions, CPPR\nis biased toward higher service temperatures, high load-bearing capacity, and thick-\nwalled components, in contrast with other bio-based systems that have their own\noptimal temperature windows and application scenarios and target in vivo/mild-\ntemperature environments with rapid response. In terms of sustainability, this study\naligns with the closed-loop remanufacturing concept reported in Nature 2024,\nhighlighting the potential for cyclic utilisation of cellulose segments and developing\nrecycle–reprint strategies (e.g., swelling/recovery and possible re-use of chain segments)\nas a promising avenue for future sustainable development.\n2. Recovery time is a key performance index for shape-memory materials. The\nmanuscript should report quantitative recovery data and compare directly with\nstate-of-the-art resins. Please also describe the testing protocol in the Methods\nsection and include appropriate statistics (sample size, mean +/- SD).\nOur response: We thank you once again for raising this point. This is a very\nconstructive suggestion that significantly enhances the scientific rigor and reliability of\nour work. In accord with your recommendation, we have now reported and\nquantitatively benchmarked our recovery data and have performed a comprehensive\ncomparison with state-of-the-art resin systems. In particular, we have addressed this by\nadding a quantitative comparison table (SI Table S6 and Table. R1) and a shape-\nmemory table (Table. R2 below) for representative biomass/biobased SMP systems\nacross multiple printing routes (FDM/DIW/DLP) reported since 2022 (see the table.\nR1 above and the excerpts in Response 1).\nWe have also carried out a detailed comparative analysis of the recovery time, as you\nhighlighted in your comment:\n(1) Comparison of “recovery rate” with FDM (thermally/magnetically triggered)\nsystems: FDM-printed PLA-based SMPs can achieve second-scale recovery under\nexternal thermal or magnetic stimulation. For instance, PLA–PBAT/Fe₃O₄\nnanocomposites achieve >90% recovery within 3–4 s in hot water (15–20 wt% Fe₃O₄),\nas well as ~96–97% Rr within 58 s under a magnetic field. By contrast, the proposed\nCPPR resin system spontaneously rebounds at room temperature without external\nstimuli after an ultra-high compressive strain of 75%, recovering its shape and load-\nbearing function within 4–5 min. This “high-load, room-temperature self-recovery”\ncondition is not directly comparable to FDM systems, which are mostly triggered above\ntheir Tg. Accordingly, the manuscript emphasises the fundamental differences in load\nlevel and environmental boundary conditions, highlighting the engineering significance\nof our stress-release-driven self-recovery without external heating.\n(2) Recovery rate and temperature window: The distinctive feature of the proposed\nCPPR resin system is the coexistence of: (I) rapid stress-release-driven rebound at room\ntemperature, (II) with high load-bearing capacity and stiffness (compressive strength\n≈115.42 MPa; E_tensile ≈1.40 GPa), (III) reproducible printing resolution and\nprocess parameters (50 μm, 8 s per layer), and (IV) stability in aqueous environments.\nThis profile is complementary to most academically reported thermally triggered SMPs\nor low-modulus soft networks, e.g., cardanol-based networks, E ≈ 0.2–2 MPa. Our\nCPPR-P maintains a relatively high storage modulus (DMA) in the room-to-medium\ntemperature range (0–100°C), with a Tg of ~90°C, indicating better suitability for\nstructural applications at elevated service temperatures. These results indicate that,\nunder a “heavy-load, thick-section” condition of 75% compressive strain, the samples\ncan fully recover their overall shape within 4–5 min, which is a reasonable recovery\ntimescale for thick, load-bearing components.\nThe olive-oil-based system reported in AFM 2025 exhibits a Tg of around 20–25°C\n(higher Tg₂) and achieves recovery within 40–100 s. It offers advantages in rapid\nresponse for thinner parts in a mild temperature window, rendering it suitable for\nbiomedical and other constrained environments. The work published in Nat. Commun.\n2023 provides a cold-programming strategy with multi-stage activatable transitions (Tc\n= 62/42/<0°C), highlighting cutting-edge capabilities in programming freedom and\nmanufacturability of complex architectures. In this context, the proposed CPPR resin\nsystem differs from previous studies in both the application domain and response\nregime and is complementary to them.\nIn addition, following your suggestion, we have fully described the testing protocol in\nthe Methods section and included appropriate statistical information (sample size; mean\n± standard deviation). Shape-memory effect (SME) protocol: Printed CPPR resin bars\n(DLP, 50 μm layers; 8 s/layer; 5 base layers at 13 s; 405 nm post-cure 5 min) were\nheated to T_prog = 100°C ~ Tg+10°C (Tg near 90°C by DMA), deformed to a target\nstrain, cooled under load to 25°C, unloaded to obtain the fixed strain (ε_fixed), and then\nreheated to T_sw = 100°C for free recovery. We report Rf and Rr as:\n𝜀 𝜀 −𝜀\nfixed fixed residual\n𝑅𝑓 = ×100%, 𝑅𝑟 = ×100%\n𝜀 𝜀\nmax fixed\nwith n = 5 specimens (reported as mean ± SD) and the recovery time t_r (≥90%\nrecovery).\nBy clearly contextualising our work within existing 3D-printed shape-memory resins\nand comparing it with previously reported systems, we are able to provide a clear,\nspecific, and integrated comparison of the research content and conclusions, thereby\nquantitatively demonstrating the advances achieved. Following these comprehensive\nadditions and revisions, the scientific rigor and readability of the manuscript have been\nsubstantially enhanced.\nTable R2 Shape Memory Test.\nSample Initial Final Applied strain Fixed Shape Shape ≥ 90% Trigger/switch\nname length residual (test gauge strain fixation recovery Recovery temperature\n(L0) plastic length=50 rate (Rf) rate (Rr) time (Ts)\nstrain mm) required\n(Tr)\nn 1 7.00 cm 2% 41.82% 24% 57.39% 91.67% ≈70 s 100 ℃\nn 2 7.00 cm 1% 56.46% 38% 67.30% 97.37% ≈60 s 100 ℃\nn 3 7.00 cm 2% 48.50% 28% 57.73% 92.86% ≈50 s 100 ℃\nn 4 7.00 cm 2% 54.90% 34% 61.93% 94.12% ≈60 s 100 ℃\nn 5 7.00 cm 1% 51.42% 30% 58.34% 96.67% ≈60 s 100 ℃\nAcross five samples and programmed strains, we obtained Rf = 60.5 % ± 4.6 %, Rr =\n94.5 % ± 2.5 %, and t_r ≈ 60–70 s at 100°C. The table also lists the residual strain\nafter recovery for each specimen. No sample fractured during programming or recovery.\n3. Some panels are discussed out of sequence (e.g., Figs. 3 and 4: panel 3g/4e\ndiscussed before 3f/4b). In addition, Figs. 2–4 (compressive, tensile, shear tests)\ncontain repetitive content and could be consolidated into one or two multi-panel\nfigures for clarity.\nOur response: Thank you for your suggestion. This is a very helpful comment that\nsignificantly improves the logical flow and readability of the manuscript. Following\nyour advice, we have revised and corrected the discussion order where previously\ninconsistent (e.g., in Figs. 3 and 4, where panels 3g/4e were discussed before 3f/4b).\nIn addition, we have re-edited and re-ordered the main text (related content of Fig. 3),\nfigure contents, and figure captions to ensure that the discussion sequence and overall\nlogic are now consistent and correct. We have also taken steps to consolidate related\ncontent across these figures where appropriate, thereby improving clarity and reducing\nrepetition (see the revised manuscript for details).\nFig. R1 Fig. 4 before modification in the original manuscript.\nFig. R2 Fig. 4 after modification in the original manuscript.\nAs regards the issue you raised here: “Moreover, Figures 2–4 (compression, tensile,\nshear tests) contain redundant content and, for the sake of clarity, could be combined\ninto one or two multi-panel figures”, we respectfully disagree that this part of the\nmanuscript contains redundant mechanical tests. We therefore provide the following\ndetailed explanation: Although the mechanical performance data in Figs. 2–4 are\nprocessed and plotted in a similar manner, thus exhibiting a certain visual similarity,\nthe underlying data and the physical meaning conveyed by each figure are completely\ndifferent. These plots represent the three most important and classical mechanical\nresponses of structural functional materials: compressive, tensile, and shear properties,\nrespectively. These distinct datasets mutually corroborate and complement each other,\nand together they are essential for demonstrating the superior mechanical performance\nof CPPR-P in this work. At the same time, we have made corresponding revisions and\ndeletions in the relevant parts of the original manuscript.\nFor your convenience and to illustrate the distinct nature of the tests, we have annotated\nall figures and contents that may appear visually similar, and they are presented below:\nFig. R3 (the revised manuscript Fig. 2) Compression mechanical properties.\nFig. R4 Tensile mechanical properties.\nFig. R5 Shear mechanical properties.\n4. The statement in lines 69–72 that “our research group has developed …” appears\nincorrect, as the cited papers seem to be not from the authors’ group. Please review\nthis wording or provide accurate references. A thorough check of the manuscript\nfor similar citation or attribution errors is also necessary.\nOur response: We appreciate the reviewer’s careful reading. You are correct; in the\noriginal text, the placement of the literature citations inadvertently implied that the cited\nworks were from our group. We have corrected this attribution and moved the citations\nat the end of the sentence that actually summarises prior plant cell-wall mechanisms.\nConcretely, the paragraph now reads: “Through bioinspired design that replicates the\nmorphological preservation and stress resilience mechanisms of natural plant cellulose,\nour research group has developed an AM material that simultaneously achieves\nexceptional mechanical strength, rapid-recovery shape memory, and optimal balance\nbetween stiffness and deformability. Since the dawn of human civilisation, the persistent\nobservation and emulation of natural systems have served as a cornerstone for\ncontinuous technological evolution and societal advancement. In plant cell walls, semi-\ndisordered lamellar architectures enable cellulose microfibrils to slide controllably\nthrough dynamic hydrogen-bond rupture and reconfiguration under external\nmechanical stress21-25.”\nThis change removes the citations from the “our research group has developed…”\nsentence and correctly places them to the prior work on cellulose microfibril sliding\n(not to our work). Furthermore, we have performed a thorough, manuscript-wide audit\nto eliminate similar issues. We revised ambiguous phrasing (e.g., replacing like “this\npaper designs …” with neutral, first-person scientific narration such as “In this work,\nwe design …”) and ensured that each citation exclusively supports the statement\nimmediately preceding it. The original location with the problematic wording and the\nrevised context are indicated in the marked section of the Introduction.\n5. The authors attribute the tensile-strength increase after 100 days in water to\n“hydrolysis optimizing the structure.” An alternative explanation could be\nadditional hydrogen bonding or physical rearrangement. To clarify the mechanism,\nthe authors may consider: (1) Providing stronger evidence for hydrolysis (e.g.,\nFTIR, XPS, solid-state NMR, molecular weight analysis, and/or TGA); (2)\nPerforming control immersions in hydrogen-bonding vs. non-hydrogen-bonding\nsolvents and reporting the results; and/or (3) Discussing swelling behavior and\nmass change during immersion.\nOur response: We appreciate the reviewer’s suggestion to clarify the mechanism\nunderlying the tensile strength increase after long-term water immersion and\nsubsequent drying. We performed a comprehensive post-immersion analysis on printed\nCPPR-P parts after 100 days in water and added the results to the SI. Jointly, the data\nsupport a dual-mechanism: limited hydrolytic scission at accessible ester/urethane sites\nplus removal of low-Mw sol fraction, followed by dry-state reinforcement via denser\nH-bonding/rearrangement. This combination rationalises the observed increase in\ntensile strength after drying.\nAdded evidences:\n(1) FTIR (bulk surface, ATR): After 100 days of immersion in water and subsequent\ndrying, the FTIR spectra demonstrated (i) a broadened O–H band (~3200–3600\ncm⁻¹) and (ii) a growth/shift of C=O features (~1700–1730 cm⁻¹) with a shoulder\nconsistent with –COOH/–O–C=O. However, C–O–C intensity (~1150 cm⁻¹) decreased,\nconsistent with mild hydrolysis and formation of more H-bond donors/acceptors in the\nFig.R6 (SI Fig. S21).\nFig. R6 FTIR analysis after immersion in water for 100 days.\n(2) XPS (C1s/O1s deconvolution): The O/C ratio increased, with an enlarged O–C=O\ncomponent (~288.5 eV in C1s; ~532.5 eV in O1s), indicating again the formation\nof new carboxylate/carboxylic groups by hydrolytic cleavage. Adventitious carbon\nwas controlled by identical cleaning/charge-ref settings in the Fig.R7 (SI Fig. S16).\nFig. R7 XPS analysis after immersion in water for 100 days.\n(3) ¹H NMR (solution of extractables): The extractable fraction from aged parts\ndisplayed new low-field methylene signals adjacent to carbonyls (≈2.2–2.5 ppm) and\na reduction of signals attributed to residual acrylate/allylic environments, evidencing\nlow-Mw hydrolysis fragments and further consumption of unreacted moieties in the\nFig.R8 (SI Fig. S17).\nFig. R8 1H NMR analysis after immersion in water for 100 days.\n(4) GPC (extractables): The chromatogram of the post-immersion extract shifted to\nlower Mn/Mw and increased in polydispersity relative to the pristine extract,\nconfirming chain scission in soluble tails/pendant segments while the bulk network\nremained insoluble in the Fig.R9 (SI Fig. S18).\nFig. R9 GPC analysis after immersion in water for 100 days.\n(5) Thermal analysis (DSC/TGA/DTG): After drying, DSC-Tg shifted upward and\nΔC_p across Tg decreased, consistent with reduced segmental mobility and higher\neffective network density. Moreover, TGA (T_5%/T_onset) shifted slightly higher and\nthe low-T mass-loss shoulder was suppressed, indicating removal of volatiles/sol\nfraction and a more thermally stable network. The char yield remained non-zero in N₂,\nas expected for cellulose-derived networks in the Fig.R10 (SI Fig. S19).\nFig. R10 TGA, DTG, and DSC analysis after immersion in water for 100 days.\n(6) Swelling study & mass-change analysis: Following the reviewer’s suggestion,\nwe have performed both a water-swelling study and a hydrolytic mass-loss analysis on\nDLP-printed, fully cured CPPR bars. The new data, including the raw spreadsheets,\nare now provided in the SI as Table S2 (Swelling) and Table S3 (Mass-loss). The key\nfindings are:\nTable R3 Swelling test results and analysis.\nSample Time (h) W0(g) Ws (g) Swelling Does it\nnumber ratio (%) degrade/disintegrate?\nn 1 6 1.11 1.52 36.94 No\nn 2 6 1.49 2.05 37.58 No\nn 3 6 1.26 1.79 42.06 No\nn 4 6 1.24 1.73 39.51 No\nn 5 6 1.50 2.07 38.00 No\nn 1 12 1.11 1.42 27.92 No\nn 2 12 1.49 1.93 29.53 No\nn 3 12 1.26 1.61 27.78 No\nn 4 12 1.24 1.57 26.61 No\nn 5 12 1.50 1.93 28.66 No\nn 1 24 1.11 1.42 27.92 No\nn 2 24 1.49 1.92 28.86 No\nn 3 24 1.26 1.60 26.98 No\nn 4 24 1.24 1.57 26.61 No\nn 5 24 1.50 1.94 29.33 No\nn 1 48 1.11 1.42 27.92 No\nn 2 48 1.49 1.90 27.52 No\nn 3 48 1.26 1.60 26.98 No\nn 4 48 1.24 1.57 26.61 No\nn 5 48 1.50 1.92 28.00 No\nSwelling (DI water, 25°C): The DLP-printed, fully cured CPPR bars exhibit\nmoderate initial water uptake that subsequently plateaus. Across n = 5 specimens per\ntime point, the swelling ratio 𝑆𝑅 = (𝑊 −𝑊 )/𝑊 ×100% was ≈ 37–39 % at 6\ns 0 0\nh, decreasing to a stable ≈ 26–29% at 12-24-48 h. No dissolution or disintegration\nwas observed at any time point up to 48 h. Thus, the DLP-printed specimens reached\nswelling equilibrium within a relatively short time (approximately 12 h). Even when\nimmersed for longer periods, they did not exhibit further water uptake or swelling,\nindicating that a stable state had been achieved.\nTable R4 Mass-loss analysis.\nSample Processing W0(g) W1(g) Mass-loss Mass loss\nNumber conditions rate (%) (g)\n(time/h)\nn 1 48 1.55 1.27 18.06 0.28\nn 2 48 1.37 1.13 17.52 0.24\nn 3 48 1.22 1.02 16.39 0.20\nn 4 48 1.54 1.28 16.88 0.26\nn 5 48 1.53 1.27 16.99 0.26\nHydrolytic degradation (DI water, 25°C, 48 h): After rinsing and drying to constant\nmass, the mass-loss fraction 𝑀𝐿 = (𝑊 −𝑊 )/𝑊 ×100% was ≈17±0.6% (n=5).\n0 1 0\nThis corresponds to removal of low-molar-mass sol fractions and limited ester\nhydrolysis at the network periphery. All specimens remained intact and could be\nhandled without damage.\nThe CPPR-P absorbs water but retains its integrity, reaching a plateau swelling of ≈\n26–29%. This is indicative of a densely crosslinked acrylate–cellulose network with\nlimited free volume. The modest ≈17% mass loss after 48 h reflects the extraction of\nresidual oligomers/sol fractions plus minor hydrolysis of surface ester linkages.\nMoreover, the absence of disintegration corroborates the robust covalent crosslink\ndensity. Together with our mechanical data, these results confirm that CPPR-P is a\nwater-stable, high-strength photoresin suitable for printed parts operating in humid or\naqueous environments. Furthermore, they confirm that the CPPR crosslinked network\nis water-stable (no disintegration) while allowing controlled water uptake, consistent\nwith its covalent network plus reversible H-bonding. The test details have been inserted\nin the Methods section and referenced the new SI tables in the Results.\nWater exposure induces localised hydrolysis at more accessible ester linkages\n(primarily at chain ends/defects), generating –OH/–COOH groups that increase H-\nbond density and facilitate chain packing upon drying. In parallel, leaching of low-\nM_w plasticising species (and minor post-curing) raises Tg and E′, yielding a\nstiffer, stronger network. Thus, the strength increase is not due to wholesale\nbackbone degradation, but to hydrolysis-assisted purification and H-bond\nreorganisation within a stable crosslinked matrix.\nTaken together, these pieces of evidence point to mild hydrolysis plus soluble\noligomer migration, followed by the formation of stronger hydrogen bonding and\nchain rearrangement upon drying, which rationalises the observed increase in\ntensile strength.\nThe corresponding data and discussion have been incorporated into the main\nmanuscript and SI.\n6. In Fig. 3g and the supporting information, TPO appears to be confused with TPU.\nPlease correct.\nOur response: We appreciate the reviewer's diligence in identifying this error. You are\ncorrect—we mistakenly labelled the reaction-condition arrow in Fig. 3g and SI now for\nFig. S15 with “TPU” instead of TPO. We have corrected both labels to “TPO (2,4,6-\ntrimethylbenzoyl-diphenylphosphine oxide), photoinitiator ” and updated the\ncorresponding figure captions. This was strictly a typographical labelling error; the\nexperiments, materials, and analysis consistently used TPO as the photoinitiator at 405\nnm, as correctly stated in the Methods section and in the description of Fig. 3g (TPO-\ndriven photoinitiated polymerisation). Consequently, this correction does not affect the\ndata, interpretations, or conclusions. We have also performed a manuscript-wide audit\nto ensure that “TPU” (thermoplastic polyurethane) appears only where it is intended,\ni.e., as a comparator material in benchmarking plots/movies, and never as a reagent or\nreaction condition. The specific changes are highlighted in the revised files for ease of\nreview and are also listed below.\nFig. R11 The revised Fig.3g in the original manuscript.\nFig. R12 The revised Fig.11 in the original supporting information.\nFig. 3g (main text): The arrow annotation has been corrected from “TPU … ” to\n“TPO (photoinitiator), 405 nm UV, DLP-like exposure conditions”. The caption now\nexplicitly defines TPO and its role in initiating free-radical polymerisation. The\nsurrounding text already states that TPO is the photoinitiator for Fig. 3g. SI Fig. 15\n(Step-3 curing schematic): The reaction-condition label has been corrected to TPO, and\nthe caption updated to state “DLP-based UV curing initiated by TPO”.\nFor absolute clarification: TPO ≠ TPU. TPO is a photoinitiator that undergoes\ncleavage under 405 nm irradiation to generate radicals and initiate double-bond\npolymerisation. TPU (thermoplastic polyurethane) is used in this manuscript solely as\na comparative material for mechanical and shape-memory benchmarking. All curing\nexperiments and interpretations were conducted with TPO as the photoinitiator (not\nTPU), under 405 nm irradiation, consistent with the Methods section and the\ndescription of Fig. 3g. The error was graphical only and has now been corrected. A full\nconsistency check has been completed, confirming that the conclusions remain\nunaffected.\n7. The manuscript contains some repetition and excessive jargon, which reduces\nreadability. Please streamline the text, remove redundancies, define abbreviations\nat first use (e.g., CPPR, HMPR, non-ECPR), and simplify language where possible.\nOur response: This is a very helpful suggestion for improving the manuscript, and we\nthank you for raising it. We carefully reflected on your comment and performed a\ncomprehensive revision of the text.\nFirst, we have re-standardised the nomenclature using a more systematic and\nscientifically sound scheme to improve clarity and reproducibility. In particular, we\nretain CPPR as the main system name and harmonised the other abbreviations to the\nformat “[chemical motif]-PR”, avoiding overly long stacked abbreviations. We also\nintroduced suffixes (L/P) to indicate the physical state of the material. This yields a\ncoherent and readable unified naming/definition scheme across the entire manuscript.\nNow, HMPR is denoted as HEMA-PR (a cellulose-free photocurable resin containing\nonly HEMA) and NE-CPPR is explicitly defined as the non-epoxidised variant of CPPR\n(without the ECH step). Where appropriate, we have added the state suffixes: CPPR-L\n(uncured liquid CPPR resin feedstock) and CPPR-P (DLP-printed CPPR specimens).\nMoreover, ECHMCC is now called MCC-E, referring to MCC molecules grafted via\nECH epoxide ring-opening etherification.\nAll abbreviations are introduced as “full name + abbreviation” at their first\nappearance in the main text and are subsequently used in abbreviated form only. In\naddition, the unified abbreviations are summarised in a dedicated “Abbreviations”\nTable S7 in the SI, and the same terminology is consistently used throughout the text,\nfigures, and captions.\nTable. R5 Summary Table of Abbreviations.\nAbbreviation Abbreviation Full name\nNew name Old name\nCPPR CPPR Cellulose-based photopolymerisable resin precursor\nCPPR-L UC-CPPR Uncured CPPR resin feedstock\nCPPR-P (None) DLP-printed CPPR specimens\nHEMA-PR HMPR Cellulose-free photocurable resin containing only HEMA\nNE-CPPR NE-CPPR Non-epoxidised variant of CPPR (without the ECH step)\nMCC-E ECHMCC MCC molecules grafted via ECH epoxide ring-opening etherification\n8. For all mechanical and shape-memory data, please report sample size (n),\nstatistical measures (mean +/- SD), and test conditions (strain rate, sample\ndimensions, testing temperature). In addition, provide sufficient details on printing\nparameters (resin viscosity, printer model/settings, layer thickness, curing\nconditions) to ensure reproducibility.\nOur response: We have revised the manuscript and SI to provide full statistical\nreporting and reproducibility details as requested.\n(1) Mechanical data (n, mean ± SD, conditions).\nTension, compression, and shear-mechanical tests were conducted on DLP-printed,\nfully cured specimens (dimensions and cross-head speeds/strain rates are now specified\nin the Methods section; testing temperature of 25 ± 0.5°C). An electronic universal\ntesting machine (SHIMADZU AGS-X 10kN) was used to determine the mechanical\nproperties of the AM CPPR samples. The tests included cyclic compression,\ncompressive strength, cyclic tensile strength, tensile strength, and shear performance\nmeasurements. Five replicates were tested per condition, with reported values\nrepresenting averages. Standard dumbbell-shaped specimens where used in the tensile\ntests (thickness: 2 mm; width: 4 mm; gauge length: 50 mm), while in the compression\nand shear tests, rectangular standard specimens (length: 10 mm; width: 10 mm; height:\n25 mm) were used at a displacement rate of 10 mm/min.\nFrom the provided dataset, the cohort statistics are:\nTensile strength: 25.14 ± 1.92 MPa (n = 5).\nCompressive strength: 114.32 ± 13.72 MPa (n = 5).\nShear strength: 24.8 ± 2.3 MPa (n = 5).\n(2) Shape-memory data (protocol, n, mean ± SD).\nAcross five samples and programmed strains, we obtained Rf = 60.5% ± 4.6%, Rr =\n94.5% ± 2.5%, and t_r ≈ 60–70 s at 100°C. The table also lists the residual strain\nafter recovery for each specimen. No sample fractured during programming or recovery.\nMore detailed testing conditions (strain rate, fixation rate, recovery rate, sample size,\ntesting temperature, etc.) have been included into SI Table S1. A demonstration video\nis also included in the SI.\nTable R6 The Shape Memory Test.\nSample Initial Final Applied strain Fixed Shape Shape ≥ 90% Trigger/switch\nname length residual (test gauge strain fixation recovery Recovery temperature\n(L0) plastic length=50 rate (Rf) rate (Rr) time (Ts)\nstrain mm) required\n(Tr)\nn 1 7.00 cm 2% 41.82% 24% 57.39% 91.67% ≈70 s 100℃\nn 2 7.00 cm 1% 56.46% 38% 67.30% 97.37% ≈60 s 100℃\nn 3 7.00 cm 2% 48.50% 28% 57.73% 92.86% ≈50 s 100℃\nn 4 7.00 cm 2% 54.90% 34% 61.93% 94.12% ≈60 s 100℃\nn 5 7.00 cm 1% 51.42% 30% 58.34% 96.67% ≈60 s 100℃\n(3) Printing parameters (reproducibility).\nWe have added a dedicated Printing Parameters table (SI Table S4), which details the\nspecific settings for every resin used (CPPR-L/-L2/-L3, HEMA-PR, NE-CPPR, and\ncomparators UVEP/PA/TPU), including the printing modality, layer thickness, per-\nlayer/base-layer exposure, number of base/buffer layers, z-lift/wait settings, and\nabsolute irradiance at the vat surface. A printer power setting of 100% corresponds to a\nstandard reference irradiance of ≈6.0 mW·cm⁻² for the MiiCraft Ultra 150 3D printer\nused; thus, a setting of 125% corresponds to 7.5 mW·cm⁻².\nThe viscosity of the uncured CPPR-L feedstock is now reported as 168 mPa·s at 25°\nC (rotational viscometer, model, and spindle/speed are stated in the Methods section),\nand the per-resin DLP settings are listed to equalise the cure depth (dose control 𝐸 =\n𝐼 ×𝑡). The printer model, wavelength, and post-cure conditions are given as well. For\nnon-DLP comparators, we have listed the SLS/FDM setpoints to keep benchmarking\nfair and reproducible.\nThese additions meet the journal’s transparency standards and ensure that our\nmechanical and shape-memory results are fully reproducible.\nTable R7 Detailed printing parameters for various types of resins.\nSample Printing Layer Single- Printing Base Buffer Printing Print\nname moulding thickness exposure substrate exposure layer machine (fill)gaps\nmethod (µm) time (s) layers time (s) number power/ (mm)\ntemperature\nCPPR-L DLP 50 8 5 13 5 125% 0.1\nHEMA-PR DLP 50 4 5 10 5 100% 0.1\nNE-CPPR DLP 50 10 5 13 5 125% 0.1\nCPPR-L2 DLP 50 14 5 18 5 150% 0.1\nCPPR-L3 DLP 50 6 5 10 5 125% 0.1\nUVEP DLP 90 2.4 5 8 5 100% 0.1\nPA SLS 150 —— —— —— —— 30 w 0.1-0.2\nTPU FDM 200 —— —— —— —— 200 ℃ 0.1\nNote: Minimum optional Layer thickness of CPPR-L is 5 µm.\nSLS: Selective Laser Sintering\nThe printer power setting of 100% corresponds to a standard reference irradiance of ≈6.0\nmW·cm⁻² for the MiiCraft Ultra 150 3D printer used in our work.\nPoint-by-point response to reviewers’ remarks\n(Blue: Reviewer’s remarks; Black: Our response)\nReviewer #1:\nGeneral Comments:\nDespite the efforts made by the authors to provide explanation to the raised points in\nthe first review round, several questions still persist that need to be addressed before\npublication:\nDespite the authors’ efforts to address the points raised during the first round of review,\nseveral questions still persist that must be clarified before the manuscript be considered\nfor publication:\nOur response: We thank the reviewer for the positive comments, especially regarding\n“several questions still persist that need to be addressed before publication:”. It is\ncrucial that these issues are raised before publication, as this helps avoid potential\nproblems and ambiguities. We also appreciate the reviewer's constructive technical\ncomments, which have helped us to improve the quality of our manuscript.\n1. In the synthetic protocols, workup details are still missing. How were the final\nproducts isolated and recovered from the reaction? How did the authors made sure\nthat the product was pure?\nOur response: We appreciate the reviewer’s request and agree that the previous version\ndid not describe the workup/purification steps with sufficient operational detail. In the\nrevised manuscript and SI, we now explicitly clarify how each intermediate/product\nwas isolated and how residual small molecules were removed and verified.\nStep 1 (epichlorohydrin grafting / MCC-E): removal of unreacted ECH. After\ncompletion of the epichlorohydrin ring-opening grafting, the key workup objective is\nto eliminate residual epichlorohydrin, which is volatile. The reaction mixture is cooled\nto room temperature and the remaining epichlorohydrin is removed by rotary\nevaporation (Vacuum degree 220-250Pa, 75 ℃, rotation speed 20, time 45 minutes)\nunder reduced pressure until a constant mass (or no further condensate) is observed.\nThis step effectively prevents carryover of unreacted ECH into Step 2 and ensures safe\nhandling and reproducibility.\nStep 2 (HEMA grafting / CPPR precursor): removal of unreacted HEMA and acid\ncatalyst. After the HEMA grafting reaction, the workup aims to remove (i) unreacted\nHEMA and (ii) the acid catalyst. We accomplish this by a combination of reduced-\npressure rotary evaporation (Vacuum degree 500-600Pa, 60 ℃, rotation speed 20, time\n60-90 minutes) (to remove residual HEMA) and neutralization (Add triethylamine\ndropwise at room temperature (1.05 equivalents relative to the acid), and stir for 10-15\nminutes, to quench the acid catalyst. And the mixture was passed through a short plug\nof basic alumina to capture the residual acid/salts.), followed by brief vacuum\ntreatment to remove trace volatiles. We have now explicitly described these operations\n(cooling → stripping of HEMA → catalyst quench/neutralization) in the revised Step-\n2 protocol.\nStep 3 (resin formulation and printed-part “purification”): removal of\nextractables and ensuring full cure. Step 3 produces a photocurable resin by\nformulation; therefore, “product purification” relevant to materials testing is performed\non the printed parts. As described in the Methods, the as-printed objects are washed in\nanhydrous ethanol to remove unreacted/soluble residues at the surface, followed by 405\nnm post-curing to drive conversion to completion before characterization.\nHow we ensured “purity” of the precursors/products. We define purity here as the\neffective removal of residual low-molecular-weight species (ECH/HEMA/catalyst)\nprior to formulation and printing. Completion of small-molecule removal is confirmed\nby (i) constant mass/no further distillate under vacuum, and (ii) the absence (or\nnegligible intensity) of characteristic vinyl signals from free HEMA in the ¹H NMR of\nthe soluble fraction, together with consistent spectroscopic and thermal features of the\nfinal materials.\nWe do not claim absolute chemical purity for a crosslinked network; instead, we ensure\nthat residual small molecules are removed and extractables are minimized, and we\nverify this using characterization: (i) spectroscopy confirms the expected\nfunctionalization of the precursor and consumption of vinyl groups after curing; (ii) the\nprinted network becomes insoluble, and only a small soluble fraction is extractable for\nGPC analysis, consistent with minimal residual low-molecular-weight species; and (iii)\nthermal analysis is consistent with a stable cured network. These points are clarified\nand cross-referenced in the revised manuscript and SI.\nRevisions implemented: We have added a dedicated “Workup” description in the Step-\n1 and Step-2 protocols to specify removal of residual epichlorohydrin, and removal of\nresidual HEMA plus acid catalyst, and we have cross-referenced the post-print\nwashing/post-curing procedure used (Step-3) to minimize extractables prior to all\ncharacterization. These revisions are described in detail in the Methods section of the\nmanuscript (lines 442–494).\n2. On the “Step 3” the authors wrote that “ethylene glycol dimethacrylate (EGDMA)\nas a reactive co-monomer (…) and 40 wt% acrylamide (C₃H₅NO) was introduced as a\ncrosslinker.” Please confirm this statement. Why bisacrylamide was added?\nPlease provide this information in the manuscript.\nOur response: Thank you for pointing out this ambiguity. We confirm that the wording\nin the previous version was inaccurate and confusing. We has been corrected in the\nrevised manuscript. And has been corrected to use standard polymer-chemistry\nterminology.\nRole clarification (EGDMA vs. acrylamide): EGDMA does not refer to\n“bisacrylamide”; rather, it stands for “ethylene glycol dimethacrylate”. In the original\nmanuscript, the imprecise wording could have led to confusion and misunderstanding\namong readers. In industrial applications, EGDMA is clearly classified as a small-\nmolecule crosslinker used to improve the mechanical properties and thermal stability\nof polymeric materials. For example, it participates in crosslinking via free-radical\nreactions but does not itself form long-chain structures; rather, it functions as a small-\nmolecule crosslinker and a reactive additive.\nIn contrast, acrylamide (C₃H₅NO) is a monofunctional vinyl comonomer and reactive\ndiluent. Acrylamide is added primarily to (i) tune viscosity and DLP processability,\nand (ii) introduce polar amide groups that strengthen intermolecular interactions (e.g.,\nhydrogen bonding) and modulate thermal–mechanical behavior. We have revised Step\n3 accordingly to avoid misinterpretation.\nAbout “bisacrylamide”: No bisacrylamide was used in this work. The term\n“bisacrylamide” appeared due to an unintended wording/naming confusion and has\nbeen removed from the manuscript and SI. The only difunctional additive used\nthroughout the formulations is EGDMA, as also summarized in Table R1 (manuscript\nTable 1) and Table S4 (SI).\nManuscript revision for clarity and reproducibility: We revised the Step 3\ndescription and the formulation table 1 to clearly define component roles as: EGDMA:\ndifunctional, low-molecular-weight additive.\nWe have made a corresponding and clearly marked revision at the relevant location in\nthe manuscript, specifying “ethylene glycol dimethacrylate (EGDMA)” (Methods, Step\n3, line 478). These changes eliminate ambiguity and align with standard definitions\nused in photopolymer network formulations.\n3. The concerns raised about the confirmation of the functionalization of MCC still\npersist. How did the 13C NMR add new information? Is it possible to exclude the\npresence of unreacted HEMA by the NMR results?\nOur response: We appreciate this continued concern and agree that FTIR/¹H NMR\nalone may not be sufficiently diagnostic for cellulose derivatives due to peak overlap\nand broadening. We therefore added ¹³C NMR specifically because it provides more\nstructure-specific carbon environments and allows us to distinguish covalently grafted\nester/methacrylate carbons from the native cellulose backbone.\n(1) What new information ¹³C NMR provides (beyond FTIR/¹H NMR).\nIn the revised SI, ¹³C NMR of MCC and CPPR shows: (i) the characteristic\ncellulose backbone signals (C1–C6) remain, confirming the cellulose scaffold\nis retained; and importantly; (ii) new resonances assigned to the ester carbonyl\ncarbon (–O–C(=O)–) and the methacrylate/vinyl carbons appear in CPPR,\nwhich are absent in pristine MCC. These features directly indicate the\nintroduction of methacrylate ester functionality onto the cellulose-derived\nprecursor and therefore provide direct evidence of functionalization at the\ncarbon level, rather than relying only on IR band shifts or proton signals that\nmay overlap.\n(2) Can NMR exclude unreacted HEMA? —what we can and cannot claim.\nWe agree that, in principle, solution-state NMR alone cannot “prove absolute\nabsence” of trace free HEMA in any polymer sample. However, the ¹H NMR\nof the soluble fraction provides a strong practical check: free HEMA exhibits\nsharp, characteristic vinyl proton peaks (typically around ~5.6–6.2 ppm) and a\ndistinct –CH₂–CH₂–OH pattern. In our spectra, these sharp monomer peaks are\nnot observed (or are negligible compared to the broad grafted signals),\nindicating that free HEMA, if present, is below the NMR detection limit. To\navoid overstatement, we revised our wording (SI, Fig. S28) to: “no detectable\nfree HEMA in ¹H NMR of the soluble fraction after workup”.\n(3) A description and discussion regarding the exclusion of unreacted\nHEMA.\nThis NMR conclusion is consistent with our revised workup: after Step 2\n(manuscript, 467-475 line), residual HEMA is removed by rotary evaporation\nunder reduced pressure, and the acid catalyst is quenched and removed using\na basic alumina plug before resin formulation. In addition, the cured CPPR\nnetwork becomes insoluble and only a limited extractable fraction can be\nanalyzed by GPC, which further supports that low-molecular-weight residues\nare minimized prior to printing and testing. Therefore, the combined evidence\n(workup + ¹³C NMR functionalization + ¹H NMR check for free monomer +\nextractables behavior) addresses the reviewer’s concern.\n4. Please revise the DS estimation using 1H NMR instead of 13C. 13C signal are not\ndirectly proportional to the number of carbons, and for this reason its use should be\navoided.\nOur response: We agree with the reviewer. In our previous version, we used ¹³C NMR\nto estimate the degree of substitution (DS). However, as correctly pointed out, ¹³C peak\nintensities are generally not directly proportional to the number of carbons due to\nrelaxation effects, NOE/decoupling conditions, and (for polymeric systems) differential\nmobility and line broadening. Therefore, we have revised the DS estimation using ¹H\nNMR instead of ¹³C NMR, and we now keep ¹³C NMR only as qualitative evidence\nsupporting successful functionalization (new carbonyl/vinyl-related signals and\nconsistent chemical-shift assignments), rather than for DS quantification.\nRevised DS method (now in SI, Fig. S32):\nIn the revised manuscript, 13C NMR is used only as a qualitative tool to confirm the\nintroduction of new carbon environments after grafting (e.g., the appearance of ester\ncarbonyl and methacrylate-related carbon signals), whereas the degree of substitution\n(DS) is re-estimated from 1H NMR, as requested.\nSpecifically, we calculated the degree of substitution of methacrylate functionalities\n(DS_MA, per anhydroglucose unit, AGU) from the methyl protons of the methacrylate\ngroup (–C(CH₃)=) and the anomeric proton of cellulose (H1) as an internal reference\n(Fig. R1).\n• Methacrylate methyl signal: δ ≈ 1.94 ppm (3H per substituent)\n• Cellulose anomeric proton (AGU H1): δ ≈ 4.90 ppm (1H per AGU)\nAfter baseline correction, we excluded solvent peaks (residual DMSO-d₆ and water)\nand integrated the selected signals using Mnova multiplet integration. Using the\nintegrals provided in the revised spectra (CPPR):\nThus,\n𝐼 /3\n𝐷𝑆 =\nCH3\n𝑀𝐴 𝐼\n𝐻1\nTherefore, the revised DS (methacrylate) of CPPR is ≈ 0.54 per AGU (i.e., ~0.54\nmethacrylate groups per glucose unit on average). This DS is consistent with the\nobserved solubility/printability of CPPR and provides a quantitative basis for\nreproducibility.\nFig. R1 S32 ¹H NMR evidence for functionalization of MCC.\nReplaced the former ¹³C-based DS description with the above ¹H NMR–based DS\nequation and calculation details, explicitly stating that ¹³C NMR is used for qualitative\nconfirmation only. Supporting Information (Fig. S32): added annotated ¹H NMR\nspectra and a short DS calculation note (with the integral regions used).\n5. Table 1 is still not sufficient to allow reproduction. What does “monomer” means\nin the Table? Why is the EGDMA crosslinker still missing?\nOur response: We agree that the previous version of Table 1 could be interpreted\nambiguously and did not fully meet reproducibility requirements. We have therefore\nrevised Table 1(Table R1 below) and the corresponding Methods text to (i) clarify the\nmeaning of “monomer”, and (ii) explicitly report the EGDMA crosslinker dosage in a\nreproducible way.\n(1) Clarification of “monomer” in Table 1. In our formulation, “monomer” refers to\nthe base photopolymerizable component of the resin, i.e., CPPR (a cellulose-\nderived methacrylated macromer) or HEMA (a small-molecule methacrylate\nmonomer), depending on the formulation. To avoid confusion, we added a footnote\ndefining these terms.\n(2) EGDMA crosslinker is now explicitly included and quantified. We\nacknowledge that EGDMA was not clearly captured in the previous table\npresentation (and in one revision stage its entry was inadvertently omitted). In the\nrevised manuscript, EGDMA is explicitly identified as a bifunctional crosslinker\nand is reported as an additional additive that was uniformly included in the final\nformulation (all experimental groups were uniformly added with 15mL) to ensure\nstraightforward reproducibility. We also clarify the reference basis of all wt%\nvalues (i.e., calculated relative to the total mass of polymerizable components in the\nresin formulation).\n(3) Reproducibility improvements. To further facilitate reproduction, Table 1 now\nreports all components in a consistent format (base component, acrylamide\ncomonomer, TPO photoinitiator, crosslinker, and EGDMA additives) and the\nMethods section cross-references this table. The full formulation details and\nprinting conditions remain provided in the Supporting Information.\nThese changes ensure that the resin compositions can be reproduced without ambiguity\nand that all polymerizable constituents (including EGDMA additives) are explicitly\naccounted for.\nTable R1 Resin component ingredient list.\nSample Reactive monomer Monomer Photoinitiator The acrylamide Additive\nname type content (TPO) Content crosslinker (EGDMA)\nCPPR-L CPPR 60wt% 0.5wt% ≈39.5wt% 15ml\nCPPR-L2 CPPR 70wt% 0.5wt% ≈29.5wt% 15ml\nCPPR-L3 CPPR 50wt% 0.5wt% ≈49.5wt% 15ml\nHEMA-PR HEMA 60wt% 0.5wt% ≈39.5wt% 15ml\nNE-CPPR CPPR without 60wt% 0.5wt% ≈39.5wt% 15ml\nECH step\n* Reactive monomer type (Base photopolymerizable component) denotes the main polymerizable species forming\nthe network:\n· Monomer in CPPR-L, L2 and L3: CPPR is a cellulose-derived methacrylated macromer (prepared in Synthesis\nSteps 1–3);\n·Monomer in HEMA-PR: HEMA is 2-hydroxyethyl methacrylate;\n· Monomer in NE-CPPR: CPPR without ECH step is the control macromer synthesized without the ECH ring-\nopening step (see Methods/SI for definitions and synthetic details).\n*EGDMA is reported as an additional additive that was uniformly included in the final formulation (all\nexperimental groups were uniformly added with 15mL) to ensure straightforward reproducibility. In industrial\napplications, EGDMA is clearly classified as a small-molecule crosslinker used to improve the mechanical\nproperties and thermal stability of polymeric materials. For example, it participates in crosslinking via free-\nradical reactions but does not itself form long-chain structures; rather, it functions as a small-\nmolecule crosslinker and a reactive additive.\n6. In Table S4, use standard irradiation units instead of %.\nOur response: We appreciate the reviewer's suggestion. The DLP printer used in this\nwork reports the light-engine output as a relative “power (%)” setting. To comply with\nstandard reporting practice, we have revised Table S4 to replace % with the\ncorresponding irradiance in mW·cm⁻² (at 405 nm), using the printer’s reference\ncalibration in our laboratory where 100% corresponds to ≈ 6.0 mW·cm⁻² for the\nMiiCraft Ultra 150 light engine. Accordingly, the settings used in this study were\nconverted as follows: 100% → 6.0 mW·cm⁻², 125% → 7.5 mW·cm⁻², and 150% → 9.0\nmW·cm⁻². We also updated the caption/note below Table S4 to explicitly state this\nconversion and removed the percentage-based description.\nTableR2 Detailed printing parameters for various types of resins.\nSample Printing Layer Single- Printing Base Buffer Printing Print\nname moulding thickness exposure substrate exposure layer machine (fill)gaps\nmethod (µm) time (s) layers time (s) number power/ (mm)\ntemperature\nCPPR-L DLP 50 8 5 13 5 7.5 mW·cm⁻² 0.1\nHEMA-PR DLP 50 4 5 10 5 6.0 mW·cm⁻² 0.1\nNE-CPPR DLP 50 10 5 13 5 7.5 mW·cm⁻² 0.1\nCPPR-L2 DLP 50 14 5 18 5 9.0 mW·cm⁻² 0.1\nCPPR-L3 DLP 50 6 5 10 5 7.5 mW·cm⁻² 0.1\nUVEP DLP 90 2.4 5 8 5 6.0 mW·cm⁻² 0.1\nPA SLS 150 —— —— —— —— 30 w 0.1-0.2\nTPU FDM 200 —— —— —— —— 200 ℃ 0.1\nNote: Minimum optional Layer thickness of CPPR-L is 5 µm.\nSLS: Selective Laser Sintering\nFDM: Fused Deposition Modeling\n7. Please provide information about how the .stl file was obtained.\nOur response: We appreciate this request and have clarified the digital workflow used\nto generate the printable .stl files. In our work, the initial geometry was created and\nedited as a .max model (3ds Max). However, .max is not a printer-readable format and\ncannot be processed directly by the DLP printing pipeline. Therefore, the model must\nbe exported to .stl, which is the standard triangulated mesh format accepted by slicing\nand printing software.\nSpecifically, the workflow is:\n1. Modeling (source file): the 3D geometry was constructed in Autodesk 3ds Max\nand saved as .max.\n2. Export to STL: the model was exported from 3ds Max as .stl (triangulated\nmesh). During export, we ensured the model with consistent surface normals\nand appropriate units (mm) to match the intended specimen dimensions.\n3. Slicing-printing preparation: the exported .stl was then imported into the DLP\nprinter software, where printing parameters (layer thickness, exposure time,\nbase layers, etc.) were set (reported in Table S4). The software then performed\nslicing to generate the layer-by-layer build file used by the printer.\nTo ensure reproducibility, we added this description to the SI (section of Model1) and\nprovided representative STL files for the standard specimens (e.g., the lattice 3D model\nspecimen STL file in the SI).\n8. What is the explanation of the authors for the results observed in the swelling tests?\nOur response: We thank the reviewer for this constructive suggestion, which\nsignificantly helps improve the scientific rigor of our manuscript. Providing an\nexplanation for the swelling results—particularly the increase in tensile strength after\n100 days of water immersion—enables us to more clearly understand and elucidate the\nhydrolytic stability and performance of the resulting materials. Order to explain the\nswelling-test results and to clarify the mechanism underlying the tensile strength\nincrease after long-term water immersion and subsequent drying. We performed a\ncomprehensive post-immersion analysis on printed CPPR-P parts after 100 days in\nwater (manuscript, 216-221 line) and added the results to the SI. Jointly, the data\nsupport a dual-mechanism: limited hydrolytic scission at accessible ester/urethane sites\nplus removal of low-Mw sol fraction, followed by dry-state reinforcement via denser\nH-bonding/rearrangement. This combination rationalises the observed increase in\ntensile strength after drying.\nAdded evidences:\n(1) FTIR (bulk surface, ATR): After 100 days of immersion in water and subsequent\ndrying, the FTIR spectra demonstrated (i) a broadened O–H band (~3200–3600\ncm⁻¹) and (ii) a growth/shift of C=O features (~1700–1730 cm⁻¹) with a shoulder\nconsistent with –COOH/–O–C=O. However, C–O–C intensity (~1150 cm⁻¹) decreased,\nconsistent with mild hydrolysis and formation of more H-bond donors/acceptors in the\nFig.R6 (SI Fig. S21).\nFig. R2 FTIR analysis after immersion in water for 100 days.\n(2) XPS (C1s/O1s deconvolution): The O/C ratio increased, with an enlarged O–C=O\ncomponent (~288.5 eV in C1s; ~532.5 eV in O1s), indicating again the formation\nof new carboxylate/carboxylic groups by hydrolytic cleavage. Adventitious carbon\nwas controlled by identical cleaning/charge-ref settings in the Fig.R7 (SI Fig. S16).\nFig. R3 XPS analysis after immersion in water for 100 days.\n(3) ¹H NMR (solution of extractables): The extractable fraction from aged parts\ndisplayed new low-field methylene signals adjacent to carbonyls (≈2.2–2.5 ppm)\nand a reduction of signals attributed to residual acrylate/allylic environments,\nevidencing low-Mw hydrolysis fragments and further consumption of unreacted\nmoieties in the Fig.R8 (SI Fig. S17).\nFig. R4 1H NMR analysis after immersion in water for 100 days.\n(4) GPC (extractables): The chromatogram of the post-immersion extract shifted to\nlower Mn/Mw and increased in polydispersity relative to the pristine extract,\nconfirming chain scission in soluble tails/pendant segments while the bulk network\nremained insoluble in the Fig.R9 (SI Fig. S18).\nFig. R5 GPC analysis after immersion in water for 100 days.\n(5) Thermal analysis (DSC/TGA/DTG): After drying, DSC-Tg shifted upward and\nΔC_p across Tg decreased, consistent with reduced segmental mobility and higher\neffective network density. Moreover, TGA (T_5%/T_onset) shifted slightly higher\nand the low-T mass-loss shoulder was suppressed, indicating removal of\nvolatiles/sol fraction and a more thermally stable network. The char yield remained\nnon-zero in N₂, as expected for cellulose-derived networks in the Fig.R10 (SI Fig.\nS19).\nFig. R6 TGA, DTG, and DSC analysis after immersion in water for 100 days.\n(6) Swelling study & mass-change analysis: Following the reviewer’s suggestion, we\nhave performed both a water-swelling study and a hydrolytic mass-loss analysis on\nDLP-printed, fully cured CPPR bars. The new data, including the raw spreadsheets,\nare now provided in the SI as Table S2 (Swelling) and Table S3 (Mass-loss). The\nkey findings are:\nTable R3 Swelling test results and analysis.\nSample Time (h) W0(g) Ws (g) Swelling Does it\nnumber ratio (%) degrade/disintegrate?\nn 1 6 1.11 1.52 36.94 No\nn 2 6 1.49 2.05 37.58 No\nn 3 6 1.26 1.79 42.06 No\nn 4 6 1.24 1.73 39.51 No\nn 5 6 1.50 2.07 38.00 No\nn 1 12 1.11 1.42 27.92 No\nn 2 12 1.49 1.93 29.53 No\nn 3 12 1.26 1.61 27.78 No\nn 4 12 1.24 1.57 26.61 No\nn 5 12 1.50 1.93 28.66 No\nn 1 24 1.11 1.42 27.92 No\nn 2 24 1.49 1.92 28.86 No\nn 3 24 1.26 1.60 26.98 No\nn 4 24 1.24 1.57 26.61 No\nn 5 24 1.50 1.94 29.33 No\nn 1 48 1.11 1.42 27.92 No\nn 2 48 1.49 1.90 27.52 No\nn 3 48 1.26 1.60 26.98 No\nn 4 48 1.24 1.57 26.61 No\nn 5 48 1.50 1.92 28.00 No\nSwelling (DI water, 25°C): The DLP-printed, fully cured CPPR bars exhibit\nmoderate initial water uptake that subsequently plateaus. Across n = 5 specimens\nper time point, the swelling ratio 𝑆𝑅 = (𝑊 −𝑊 )/𝑊 ×100% was ≈ 37–39 % at\ns 0 0\n6 h, decreasing to a stable ≈ 26–29% at 12-24-48 h. No dissolution or disintegration\nwas observed at any time point up to 48 h. Thus, the DLP-printed specimens\nreached swelling equilibrium within a relatively short time (approximately 12 h).\nEven when immersed for longer periods, they did not exhibit further water uptake\nor swelling, indicating that a stable state had been achieved.\nTable R4 Mass-loss analysis.\nSample Processing W0(g) W1(g) Mass-loss Mass loss\nNumber conditions rate (%) (g)\n(time/h)\nn 1 48 1.55 1.27 18.06 0.28\nn 2 48 1.37 1.13 17.52 0.24\nn 3 48 1.22 1.02 16.39 0.20\nn 4 48 1.54 1.28 16.88 0.26\nn 5 48 1.53 1.27 16.99 0.26\nHydrolytic degradation (DI water, 25°C, 48 h): After rinsing and drying to\nconstant mass, the mass-loss fraction 𝑀𝐿 = (𝑊 −𝑊 )/𝑊 ×100% was\n0 1 0\n≈17±0.6% (n=5). This corresponds to removal of low-molar-mass sol fractions and\nlimited ester hydrolysis at the network periphery. All specimens remained intact\nand could be handled without damage.\nThe CPPR-P absorbs water but retains its integrity, reaching a plateau swelling of\n≈ 26–29%. This is indicative of a densely crosslinked acrylate–cellulose network\nwith limited free volume. The modest ≈17% mass loss after 48 h reflects the\nextraction of residual oligomers/sol fractions plus minor hydrolysis of surface ester\nlinkages. Moreover, the absence of disintegration corroborates the robust covalent\ncrosslink density. Together with our mechanical data, these results confirm that\nCPPR-P is a water-stable, high-strength photoresin suitable for printed parts\noperating in humid or aqueous environments. Furthermore, they confirm that the\nCPPR crosslinked network is water-stable (no disintegration) while allowing\ncontrolled water uptake, consistent with its covalent network plus reversible H-\nbonding. The test details have been inserted in the Methods section and referenced\nthe new SI tables in the Results.\nWater exposure induces localised hydrolysis at more accessible ester linkages\n(primarily at chain ends/defects), generating –OH/–COOH groups that increase H-\nbond density and facilitate chain packing upon drying. In parallel, leaching of low-\nM_w plasticising species (and minor post-curing) raises Tg and E′, yielding a\nstiffer, stronger network. Thus, the strength increase is not due to wholesale\nbackbone degradation, but to hydrolysis-assisted purification and H-bond\nreorganisation within a stable crosslinked matrix.\nTaken together, these pieces of evidence point to mild hydrolysis plus soluble\noligomer migration, followed by the formation of stronger hydrogen bonding and\nchain rearrangement upon drying, which rationalises the observed increase in\ntensile strength. The corresponding data and discussion have been incorporated into\nthe main manuscript and SI.\n9. The DSC analysis is still confuse. Adjust the baseline, Which run is presented? Try\nto perform the test before thermal degradation of the material.\nOur response: We agree that our previous DSC presentation was not sufficiently clear\nregarding (i) baseline treatment, (ii) which scan was shown, and (iii) whether the\nselected temperature range could be affected by thermal degradation. We have therefore\nrepeated the DSC measurements and revised both the data processing and the figure\npresentation.\n1. Baseline correction (now clarified and documented).\nAll DSC thermograms were reprocessed with a consistent baseline correction\nprocedure using the instrument analysis software. The updated reply now\nprovides both the raw curves and the baseline-corrected curves for CPPR-L\nand CPPR-P, so that the baseline adjustment and its effect on the heat-flow\ntrace can be directly inspected (Fig. R7).\nFig. R7 DSC thermograms of CPPR-L and CPPR-P before and after baseline correction.\n2. Compared with the previous (uncorrected / ambiguously reported) DSC\nplot, the new baseline-corrected second-run DSC (Fig. 5f and the below\nFig. R8) provides a clearer and more physically meaningful description.\n(i)Removal of misleading drift: the earlier plot contained apparent baseline\ncurvature/tilting, which can artificially amplify or mask small transitions.\nAfter baseline correction, the curves show a stable baseline and a consistent\ntransition region, making the interpretation reproducible. (ii) Clear\nidentification of the switching transition: the corrected DSC traces reveal the\nprimary thermally activated transition (glass transition–type switching event)\nused for the shape-memory behavior, which is consistent with the thermo-\nmechanical switching observed by DMA. (iii) Curing or structure dependence:\nCPPR-P (printed + post-cured) exhibits a more “network-dominated” thermal\nresponse than CPPR-L. In particular, the printed network typically shows\nreduced low-temperature relaxation features and a shift of the switching\ntransition toward higher temperature and/or a more pronounced ΔCp step,\nconsistent with higher double-bond conversion and a higher effective crosslink\ndensity after printing/post-curing. Conversely, CPPR-L can contain small\ncontributions from residual monomer/low-molecular components and physical\nrelaxation, which are minimized after curing.\nFig. R8 DSC thermograms of CPPR-L and CPPR-P after remeasurement.\n3. In the revision, the DSC curves reported in Fig. 5f correspond to the\nsecond heating scan (after the first heating/cooling cycle) to eliminate thermal\nhistory and to avoid misinterpretation from physical aging/enthalpy relaxation\nand possible residual volatile release. This is now clearly indicated in the figure\ncaption and in the Methods section.\nThe previously shown DSC curves were replaced by newly collected data with baseline\ncorrection and explicit reporting of the scan number. The baseline-corrected second-\nrun DSC reveals the dominant thermal switching transition used for the shape-memory\neffect. Compared to CPPR-L, CPPR-P shows a network-reinforced thermal response,\nconsistent with higher conversion and higher effective crosslink density after\nprinting/post-curing, which suppresses relaxation contributions from low-molecular\ncomponents and enhances the switching signal.\n10. Why deuterated DMSO was used as mobile phase for GPC? Not sure if GPC\ninformation is valuable to the present manuscript.\nOur response: Thank you for raising this point. First, we clarify that our GPC does not\nattempt to measure the molecular weight of the entire printed CPPR network, which is\ninsoluble after DLP curing. Instead, GPC was performed only on the DMSO-d6-\nsoluble/extractable (“sol”) fraction obtained from the printed specimens, as now\nexplicitly stated in the SI caption (SI Fig. S30). This soluble fraction contains\nunreacted/partially reacted pendant chains, oligomers, and other extractables that can\nbe dissolved and therefore chromatographically analyzed, whereas the load-bearing\ncrosslinked network remains insoluble. In this context, GPC is used as a\nsupportive/qualitative indicator of curing and aging behavior rather than an absolute\ndescriptor of the crosslinked network.\nRegarding the use of DMSO-d₆, we agree that deuteration is not intrinsically required\nfor GPC. We used DMSO-d₆ primarily because (i) the cellulose-derived CPPR\nextractables are highly polar and hydrogen-bonding, and DMSO-d6 is the most reliable\nsolvent to ensure complete dissolution and avoid aggregation/partial solubility artifacts\n(which was the main source of uncertainty in our previous GPC traces); and (ii) DMSO-\nd₆ was the high-purity DMSO available in our laboratory and was also used for the\ncomplementary solution-state NMR characterization, allowing consistent sample\nhandling. Importantly, the isotopic substitution (DMSO vs. DMSO-d₆) does not change\nthe interpretation of our GPC results because SEC separation is governed by\nhydrodynamic volume; therefore, we have revised the text to emphasize “DMSO-d6-\nsoluble fraction” and positioned the GPC data as supporting evidence alongside\nFTIR/XPS/NMR and thermal analyses.\nTo address the reviewer’s concern about GPC information is valuable to the\npresent manuscript, we also revised the manuscript and SI wording so that GPC is not\npresented as a stand-alone proof. Rather, it supports the following limited claims: (1)\nafter DLP curing, the extractable fraction shows an apparent shift consistent with chain\ngrowth/network formation; and (2) after water aging, the extractable fraction shifts\ntoward lower molar mass with broader dispersity, consistent with mild scission in\nsoluble/dangling segments, while the bulk network remains intact—fully consistent\nwith our spectroscopic and thermal signatures (SI Fig. S30 and related discussion).\nReviewer #2:\nGeneral Comments:\nI co-reviewed this manuscript with one of the reviewers who provided the listed reports.\nThis is part of the Nature Communications initiative to facilitate training in peer review\nand to provide appropriate recognition for Early Career Researchers who co-review\nmanuscripts.\nReviewer #3:\nGeneral Comments:\nThis paper reports a cellulose-based photopolymerizable resin (CPPR) with\nexceptional stiffness-deformability synergy and spatiotemporal shape memory\ncapabilities. A bionic structure design approach was proposed, which transforms\nbrittle photocurable 3D-printing materials into bio-inspired structures. This paper\ncarries interesting results. However, there are some concerns regarding the synthesis\nof CPPR and its characteristics.\nOur response:We greatly appreciate the reviewer’s positive comments on our\nmanuscript. We are particularly grateful for their recognition of the innovative aspects\nand the interesting results presented in our work.\n1. Lines 64-67: The authors said, “However, the potential of using cellulose as a\nprimary feedstock for directly synthesizing high-performance printable materials\nremains either unexplored or results in products with compromised mechanical and\nfunctional properties.” They did not recognize that nanocellulose has been 3D\nprinted for structural materials by esterifying nanocellulose with green crosslinkers\n(Adv. Mater. Interf. 9(16), 2200280, May 2022; ACS Appl. Nano Mater. 5, 5680-\n5687, April 4, 2022; Carbo. Pol. 320, 121197, November 2023; ACS Omega 9(22)\n23442-23450, May 2024; ACS Appl. Energy Mater. 8(1) 267–275, Jan 2025).\nOur response: We thank the reviewer for pointing out this issue. We agree that, since\n2022, several novel works on direct ink writing (DIW) 3D-printed structural materials\nbased on nanocellulose (either esterified with green crosslinkers or blended with lignin\nand related components) have been reported, achieving high mechanical strength and\ngood shape retention (Adv. Mater. Interf. 9(16), 2200280, May 2022; ACS Appl. Nano\nMater. 5, 5680–5687, April 4, 2022; Carbo. Pol. 320, 121197, November 2023; ACS\nOmega 9(22), 23442–23450, May 2024; ACS Appl. Energy Mater. 8(1), 267–275, Jan\n2025).\nWe have now added and properly cited these references in the Introduction section.\nIn addition, we have introduced a new “quantitative comparison table” (SI Table S5),\nwhich juxtaposes our work with these studies in terms of bending/compressive strength\nand modulus, printing method, crosslinking chemistry, shape-memory metrics\n(Rf/Rr/recovery time), printing resolution, and cyclic durability. These additions\nquantitatively summarise the advances in this field, while also clarifying that the above\nDIW systems primarily emphasise “structural strength/shape retention”, whereas the\npresent work focuses on “cellulose as the main-chain source → direct DLP\nprinting → photo-crosslinked networks imparting shape-memory and anti-fatigue\nproperties”. Therefore, the two lines of research address different but complementary\nquestions and technical routes. The corresponding revisions have been incorporated\ninto the Introduction section and the Related Work subsection of the revised manuscript.\nClarification and revision for original lines 64–67: Previous studies on 3D printing\nof biomass and its derivatives have demonstrated that nanocellulose can be esterified\nwith green small molecules (e.g., citric acid) or blended with lignin and related\ncomponents, thereby enabling DIW printing of high-solids-content (≥25 wt%)\nstructural parts with high strength and good shape retention (bending strength of 83–\nas the primary carbon source to directly synthesise photocurable resins suitable for DLP\nprinting (rather than aqueous paste-type DIW). While maintaining high mechanical\nperformance, these resins endow the printed structures with pronounced shape-memory\nbehaviour and multi-cycle anti-fatigue capability. This approach addresses the\nlimitations of existing DIW structural materials by making the final product\n“photopatternable, rapidly formable, and capable of programmable deformation”.\nTable R1 Comparison of the CPPR resin system developed in this study with previously reported\n3D printing of cellulose-based materials.\nComparison Ref1 Ref2 Ref3 Ref4 Ref5 Ref6 This work\nwork\nTypes\nPrinting DIW → DIW → DIW→ DIW DIW → DIW → Highly\nmethod 140 ℃ freeze- clean → clean cleanroom customised, high-\n/20 min drying/slo room control room drying/fil precision DLP\nvacuum w drying in drying led drying + m forming printing\nesterifica clean room (no drying post\ntion resin mouldi curing\ncuring infusio ng\nn)\nKey points of ≈ 25.50 wt% 25.46 25 25.45 Polycarbo Modified cellulose\ncrosslinking/c 25.94wt NC; 2.50– wt% wt% wt% nate as the main\nuring and % NC; 10 wt% NC + grade NC+alkal substrate+ reactive monomer\nformulation CA is a PVA; 15 wt% NC; A i lignin; 2-8wt% → photo\ngreen Improved PVA; woode LG is NC crosslinking\ncrosslink interlayer Resin n base used as a\ning adhesion free is used “nano\nagent; infusio to filler/adhe\nEmphasi n acceler sion aid”\ns on ate\ninterlaye bottom\r bonding\nRepresenting Bending Bending Bendin Bendin Bending Tensile Compressive\nmechanical strength strength g g strength strength strength ≈ 115.4\nproperties (at 82.78 ± 120 ± 2 strengt strengt 102.93 ± 139.92 ± MPa; Tensile\nroom 2.79 MPa; h 94.78 h 149 0.96 MPa; 5.3 MPa; strength ≈ 27-\ntemperature) MPa; Bending ± 3.18 ± 2 Bending Young's 28 MPa (see\nBending modulus 15 MPa; MPa; modulus modulus manuscript)\nmodulus ± 0.1 GPa Modul Bendin 9.05 ± 5.74 ±\n6.97 ± us 9.00 g 0.07 GPa 0.32 GPa;\n0.38 GPa ± 0.27 modul Fracture\nGPa us 15 ± elongation\n0.8 6.13 ±\nGPa 0.15%\nShape Not Not Not Not Not Not Rf:≈60.54%; Rr:\nmemory reported reported reporte reporte reported reported 94.54%; Tr: ≈\nindex d d 60s\n(Rf/Rr/time)\nRepresenting No No No No Small No Adjustable and\nresolution & volume customisable\nloop shrinkage printing\nfluctuatio resolution and\nns multi-cycle fatigue\nresistance (see\nmanuscript)\nRemarks Green Improved Slow The The Potential Different from the\ncross- interlayer drying author addition of NC DIW structural\nlinking, adhesion curing refers of lignin membrane materials listed\nhigh and for to it as fillers structural above in terms of\nmechani environme shrinka one of significan componen technical path and\ncal ntally ge the tly ts in target function:\npropertie friendly crack highest improves energy emphasising\ns, and structure prevent strengt interlayer devices/te “photolithograph\nsignifica ion hs of adhesion nsile y+shape memory”\nnt DIW and conditions\nrepeatabi extrud repeatabil\nlity ed NC ity\ncurrent\nly\navailab\nle\nNote:\nRef1 :High-solids-content nanocellulose (NC)+citric acid (CA) esterification (Adv. Mater.\nInterf. 9(16), 2200280, May 2022),\nRef2 :high-solids-content nanocellulose+PVA adhesion aid (ACS Appl. Nano Mater. 5,\n5680-5687, April 4, 2022),\nRef3 :High-solids-content nanocellulose+PVA clean room “green composite” (Polymers\n15, 669, Latif et al., 2023),\nRef4 :High-solids-content nanocellulose+substrate engineering (wood substrate) (Carbo.\nPol. 320, 121197, November 2023),\nRef5: Nanocellulose/Lignin Blend (LG-NC) (ACS Omega 9(22) 23442-23450, May\n2024),\nRef6 :3D printing of high-strength nanocellulose film (energy device) (ACS Appl. Energy\nMater. 8(1) 267–275, Jan 2025),\nOur work: Cellulose-based photopolymerisation DLP printing resin. Direct\nextrusion (DIW) extrusion, Digital Light Processing (DLP).\nThe Table above incorporates all studies explicitly mentioned by the reviewer and\nprovides concrete experimental values for direct cross-checking. Most DIW-based\nworks do not report shape-memory performance, whereas in our study, the shape-\nmemory effect arises from the programmable recovery of a photo-crosslinked network.\nAccordingly, we have revised and clarified our discussion and positioning of the related\nwork as follows:\n(1) Different material targets and processing routes: The DIW–NC systems use\nwater-based, high-solids-content pastes as inks. Citric-acid esterification or lignin/PVA\nblending is employed to improve interlayer adhesion and shape fidelity, and the\nstructures are formed via direct extrusion followed by post-curing. In contrast, our work\nuses cellulose as the main-chain carbon source, chemically modifying it to obtain a low-\nviscosity photocurable resin compatible with DLP printing. This approach successfully\naddresses the “photolithographic processability + high mechanical performance +\nshape-memory capability” trilemma.\n(2) Different performance emphases: DIW–NC systems excel in static flexural\nstrength and modulus (up to ≈149 MPa and ≈15 GPa, respectively), but they do not\nprovide high-precision customisation or rapid forming capability, nor do they typically\nreport shape-memory-related metrics. Our study, not only delivers high strength (e.g.,\ncompressive strength ≈115 MPa) but also offers a full shape-memory profile\nincluding Rf/Rr, recovery time, and cyclic durability.\n(3) Complementary scalability and application scenarios. DIW–NC systems are\nwell suited for large-scale structures and biomedical scaffolds. In contrast, the DLP–\nCPPR resin system developed in this work is specifically tailored for high-resolution,\ncomplex-topology, and programmable deformation devices, e.g., impact-absorbing\nenergy dissipators and integrated soft–hard structures.\n2. The synthesis of ECHMCC, UC-CPPR, and CPPR: The authors did not explain\nclearly how to synthesize them step by step in Methods and Supporting Information.\nMCC is crystalline cellulose, and ECHMCC seems an amorphous cellulose, as\nshown in SI Figure 13. It seems that the authors dissolved MCC and performed\nepoxidation. Once it is true, then the cellulose solvent could influence all of\nproducts. The authors need to explain it.\nOur response: Thank you very much for your suggestion. Upon review, we realised\nthat key methodological details were indeed missing, preventing a clear and\nunambiguous description of the synthetic route for obtaining the photocurable resin.\nWe have now provided sufficient detail to ensure reproducibility of the reaction and\nhave incorporated this information into the Methods section of the revised manuscript\n(lines 439–477). We are grateful to you for pointing out this critical omission.\nSynthesis – Step 1 the prepared process of MCC epichlorohydrin.\nThe reaction shown in Fig. R1(Fig. S13 of the SI) corresponds to Step 1 of the synthesis.\nFirst, an epoxide ring-opening reaction occurs between the cellulose chains and\nepichlorohydrin. Briefly, 2 g of pretreated microcrystalline cellulose (MCC) was\ninitially allowed to swell and uniformly dispersed in 70 mL of DMSO and maintained\nat 50°C in a water bath until a homogeneous suspension was obtained. Subsequently,\nepichlorohydrin (40 mL) was placed in a dropping funnel and added dropwise at a rate\nof 10 mL h⁻¹. Then, 15 mL of 30 wt% aqueous NaOH solution was added dropwise\nover 30–45 min using a dropping funnel. The mixture was then heated to 80–85°C and\nallowed to react for a further 4 h. After cooling the reaction system to room temperature,\nthe functionalised MCC precursor was obtained. Under alkaline conditions at 80°C, the\nepoxide group of epichlorohydrin underwent a ring-opening reaction to generate\nreactive sites, at which point the primary hydroxyl group at the C6 position of cellulose\nreacted with it. The resulting product is named as MCC-E.\nFig. R1 Epoxide ring-opening reaction between cellulose molecules and epichlorohydrin.\nSynthesis – Step 2 the synthetic of Cellulose-based photopolymerisable resin\n(CPPR) precursor .\nThe reaction depicted in Fig. R2(Fig. 14 of the SI) corresponds to Step 2 of the\nsynthesis. Based on the precursor obtained in Step 1, free-radical photoreactive groups\nwere grafted onto the cellulose backbone. The product from Step 1 was transferred into\na 500 mL round-bottom flask and 0.5 wt% methanesulfonic acid (CH₃SO₃H) was used\nas a catalyst. Subsequently, 50 wt% hydroxyethyl methacrylate(HEMA) (C₆H₁₀O₃) was\nadded to introduce the free-radical photoreactive grafting groups, and the mixture was\nstirred at 70°C in a water bath for 6 h. After reaction completion, the system was cooled\nto 50°C and maintained for a further 4 h to ensure complete conversion. The resulting\nproduct is Cellulose-based photopolymerisable resin (CPPR) precursor used for DLP\nadditive manufacturing.\nFig. R2 Graft-free radical photosensitive reactive groups.\nSynthesis – Step 3 the synthetic of Cellulose-based photocurable print resin liquid\n(CPPR-L).\nThe reaction exhibited in Fig. R3(Fig. 15 of the SI) corresponds to Step 3, which details\nthe photo-initiated free-radical polymerisation of the CPPR resin. First, 150 mL of the\nCPPR resin monomer prepared in Step 2 was transferred into a 500 mL round-bottom\nflask, followed by the addition of 15 mL of ethylene glycol dimethacrylate\n(EGDMA) as a reactive co-monomer for the subsequent free-radical polymerisation.\nThe mixture was stirred at 50°C until complete dissolution. Next, the temperature\nwas lowered to 30°C (to prevent premature partial polymerisation), and 40 wt%\nacrylamide (C₃H₅NO) was introduced as a crosslinker. The reaction was allowed to\nproceed under stirring for 30 min at 30 °C. Subsequently, 0.1 wt% N,N′-\nmethylenebisacrylamide (MBA) was introduced, and stirring continued for another 30 min.\nFinally, 0.5 wt% TPO was added as the photoinitiator, and stirring was continued until a\nhomogeneous Cellulose-based photocurable print resin liquid (CPPR-L) capable of\nundergoing UV-induced free-radical polymerization was obtained. The CPPR-L2 and\nCPPR-L3 were fabricated according to the different content of CPPR and acrylamide.\nHEMA-PR refers photocurable print resin only with HEMA. NE-CPPR refers CPPR\nwithout MCC epichlorohydrin step.\nFig.R3 DLP-based UV curing via free radical polymerisation and crosslinking.\nRegarding the issue you raised in your revision comments concerning MCC dissolution\nand the change in crystallinity (SI Fig. S23), we would like to thank you for pointing\nthis out, as it helps make our manuscript more scientifically rigorous and easier to\nfollow.\nFirst, we did not dissolve MCC in a cellulose-dissolving medium (such as DMAc/LiCl,\nionic liquids, or NaOH/urea). Step 1 is explicitly conducted in a heterogeneous\nalkaline system at 80 °C, where MCC is in a swollen/dispersed state. ECH reacts with\nthe C6–OH groups of MCC via epoxide ring-opening etherification and results in a\nsmall degree of interchain bridging; it is not a dissolution process mediated by “true\ncellulose solvents”.\nThe supporting data and analytical evidence confirm this:\n(1) The process description in SI Fig. S13 clearly states “alkaline conditions at 80°\nC, with C6 participating in the reaction”, which indicates that ECH reacts mainly\nwith primary hydroxyls at the C6 position to form ether linkages and occasional\ninterchain bridges.\n(2) Fig. R4 (SI Fig. S22) FTIR shows the appearance/intensification of C–O–C bands\nat 1120–1160 cm⁻¹.\nFig. R4 FTIR spectra of microcrystalline cellulose (MCC) raw materials and epichlorohydrin-\nmodified cellulose molecules (MCC-E) via ring-opening epoxidation (Synthesis - Step 1).\n(3) Fig. R5 (SI Fig. S20) ¹H NMR reveals a new signal region at 3.6–4.2 ppm.\nFig. R5 1H NMR spectra of MCC molecular raw material and epichlorohydrin-modified\ncellulose molecules via ring-opening epoxidation (Synthesis - Step 1).\n(4) Fig. R6 (SI Fig. S23) XRD demonstrates only a decrease in the\nintensity/crystallinity of the cellulose I (002) reflection, without conversion to\ncellulose II or the presence of a fully amorphous halo.\nFig. R6 XRD patterns of MCC raw materials and epichlorohydrin-modified cellulose\nderivatives via ring-opening epoxidation (Synthesis - Step 1).\nTaken together, these features are indicative of substitution-induced disorder, rather\nthan a dissolution–regeneration pathway of cellulose. The XRD changes are consistent\nwith the chemical “anchors” observed via FTIR/NMR and can be attributed to\netherification substitution + local crosslinking that disrupts the hydrogen-bond network,\nrather than to any solvent-induced regeneration process.\nFurthermore, after Step 2 (HEMA grafting), the crystalline form and overall\ncrystallinity of the material remain essentially unchanged (SI Fig. S25). This further\nsupports that the “apparent amorphisation” originates from chemical substitution and\nhydrogen-bond disruption, and that no dissolution–regeneration of cellulose has\noccurred.\nIn Step 3, the acrylamide network introduced by photocuring may induce new ordered\npeaks in the XRD patterns of the DLP-printed samples (SI Fig. S12). This reflects an\nincrease in order associated with the final covalent network, which is not contradictory\nto the “local disordering” observed in the first two steps. Instead, it represents a new\norder parameter that emerges only following DLP printing and curing.\nAs regards the concern that “the solvent may affect all products”, we explicitly state in\nthe Methods section that no cellulose-dissolving solvent system was utilised in the\nsynthetic procedures. DMSO-d₆ was employed only as a characterisation solvent for\nNMR measurements (on separately prepared samples) and was not involved in any\nother synthetic pathways.\n3. The authors should carefully use the acronyms by denoting full names, for example,\nECHMCC.\nOur response: Thank you for your suggestion. We acknowledge the need for clear and\nconsistent abbreviation usage. We have re-standardised the nomenclature using a more\nsystematic and scientifically sound scheme to improve clarity and reproducibility. In\nparticular, we retain CPPR as the main system name and harmonised the other\nabbreviations to the format “[chemical motif]-PR”, avoiding overly long stacked\nabbreviations. We also introduced suffixes (L/P) to indicate the physical state of the\nmaterial. This yields a coherent and readable unified naming/definition scheme across\nthe entire manuscript.\nNow, HMPR is denoted as HEMA-PR (a cellulose-free photocurable resin containing\nonly HEMA) and NE-CPPR is explicitly defined as the non-epoxidised variant of CPPR\n(without the ECH step). Where appropriate, we have added the state suffixes: CPPR-L\n(uncured liquid CPPR resin feedstock) and CPPR-P (DLP-printed CPPR specimens).\nMoreover, ECHMCC is now called MCC-E, referring to MCC molecules grafted via\nECH epoxide ring-opening etherification.\nAll abbreviations are introduced as “full name + abbreviation” at their first appearance\nin the main text and are subsequently used in abbreviated form only. In addition, the\nunified abbreviations are summarised in a dedicated “Abbreviations” table in the SI,\nand the same terminology is consistently used throughout the text, figures, and\ncaptions.\nTable. R2 Summary Table of Abbreviations.\nAbbreviation Abbreviation Full name\nNew name Old name\nCPPR CPPR Cellulose-based photopolymerisable resin precursor\nCPPR-L UC-CPPR Uncured CPPR resin feedstock\nCPPR-P (None) DLP-printed CPPR specimens\nHEMA-PR HMPR Cellulose-free photocurable resin containing only HEMA\nNE-CPPR NE-CPPR Non-epoxidised variant of CPPR (without the ECH step)\nMCC-E ECHMCC MCC molecules grafted via ECH epoxide ring-opening etherification\n4. The mechanical properties of CPPR (compressive strength of 115.42 MPa and\nstiffness of 1404.16 MPa) are much lower than the nanocellulose 3D printed results.\nThe authors need to compare their results with previously reported ones.\nOur response: We thank the reviewer for once again raising the issue of how our work\nrelates to and compares with previously reported 3D-printing results based on\nnanocellulose. As discussed in our response to your earlier Comment #1, we fully\nacknowledge that multiple studies since 2022 have reported direct ink writing (DIW)\n3D-printed structural materials based on nanocellulose, achieving high strength and\ngood shape fidelity (16-20).\nIn this revision, we have addressed this concern by adding a “quantitative comparison\ntable” (Table. R1/SI Table S5 ) that places our work side-by-side with these studies\nalong several dimensions, including material system, printing/forming method,\nmechanical strength, crosslinking chemistry, shape-memory metrics\n(Rf/Rr/recovery time), printing resolution, and cyclic durability. These comparisons\nquantitatively illustrate the progress in this field, while also clarifying that the above\nDIW systems primarily emphasise “structural strength/shape retention”, whereas the\npresent work focuses on “cellulose as the main-chain source → direct DLP\nprinting → photo-crosslinked networks imparting shape-memory and anti-fatigue\nproperties”. Therefore, the two lines of research address different but complementary\nscientific questions and technical routes. The corresponding revisions have been\nincorporated into the Introduction section and the Related Work subsection of the revised manuscript.\nBy comparing our research results with previously reported 3D printing results of\nnanocellulose, we can draw a systematic, specific, and comprehensive comparison\nconclusion. Most DIW-based works do not report shape-memory performance, whereas\nin our study, the shape-memory effect arises from the programmable recovery of a\nphoto-crosslinked network. Accordingly, we have revised and clarified our discussion\nand positioning of the related work as follows:\n(1) Different material targets and processing routes: The DIW–NC systems use\nwater-based, high-solids-content pastes as inks. Citric-acid esterification or lignin/PVA\nblending is employed to improve interlayer adhesion and shape fidelity, and the\nstructures are formed via direct extrusion followed by post-curing. In contrast, our work\nuses cellulose as the main-chain carbon source, chemically modifying it to obtain a low-\nviscosity photocurable resin compatible with DLP printing. This approach successfully\naddresses the “photolithographic processability + high mechanical performance +\nshape-memory capability” trilemma.\n(2) Different performance emphases: DIW–NC systems excel in static flexural\nstrength and modulus (up to ≈149 MPa and ≈15 GPa, respectively), but they do not\nprovide high-precision customisation or rapid forming capability, nor do they typically\nreport shape-memory-related metrics. Our study, not only delivers high strength (e.g.,\ncompressive strength ≈115 MPa) but also offers a full shape-memory profile\nincluding Rf/Rr, recovery time, and cyclic durability.\n(3) Complementary scalability and application scenarios. DIW–NC systems are\nwell suited for large-scale structures and biomedical scaffolds. In contrast, the DLP–\nCPPR resin system developed in this work is specifically tailored for high-resolution,\ncomplex-topology, and programmable deformation devices, e.g., impact-absorbing\nenergy dissipators and integrated soft–hard structures.\n5. Lines 345-346: “Moreover, the cyclic compression tests confirmed the excellent\nshape memory 345 recovery function of the material (Fig. 5c).” Fig. 5c shows\nnothing but pseudo-elastic (or super-elastic) behavior of CPPR material. Once\nCPPR has shape memory effect, then its quasi-plastic behavior (residual strain)\nneeds to be shown. Otherwise, it may not be appropriate that CPPR has shape\nmemory effect.\nOur response: We appreciate the reviewer’s observation and agree that the original\nFig. 5c demonstrated a thermal pseudo-elastic (superelastic-like) recovery under cyclic\ncompression at room temperature, which alone is insufficient to evidence thermally\ntriggered shape-memory effect (SME). To definitely address this concern, we have\nperformed additional thermally triggered shape memory experiments, and the results\nare presented in the Supplementary Materials. In these new tests, the material was\nprogrammed into a temporary shape via tensile loading and then heated to 100°C to\ntrigger shape recovery (Table.R3). The shape memory performance is now\nquantitatively confirmed by a high shape fixity ratio (Rf), a high shape recovery ratio\n(Rr), and a rapid recovery time (Tr). All these metrics demonstrate that the deformed\nshape is fully fixed at room temperature and almost completely recovered upon heating.\nWe have also included a video in the SI showing the sample programming, shape\nfixation at room temperature, and subsequent recovery upon heating, providing clear\nvisual evidence of the SME. All in all, we have (i) revised the text around Fig. 5c to\ndescribe it strictly as cyclic superelastic-like recovery, and (ii) added a dedicated SME\nprotocol, dataset, and video (Supplementary Movie S5) showing programming–\nfixing–recovery with the required quantitative metrics.\nTable R3 Shape Memory Test.\nSample Initial Final Applied strain Fixed Shape Shape ≥ 90% Trigger/switch\nname length residual (test gauge strain fixation recovery Recovery temperature\n(L0) plastic length=50 rate (Rf) rate (Rr) time (Ts)\nstrain mm) required\n(Tr)\nn 1 7.00 cm 2% 41.82% 24% 57.39% 91.67% ≈70 s 100℃\nn 2 7.00 cm 1% 56.46% 38% 67.30% 97.37% ≈60 s 100℃\nn 3 7.00 cm 2% 48.50% 28% 57.73% 92.86% ≈50 s 100℃\nn 4 7.00 cm 2% 54.90% 34% 61.93% 94.12% ≈60 s 100℃\nn 5 7.00 cm 1% 51.42% 30% 58.34% 96.67% ≈60 s 100℃\nResults: Across five samples and programmed strains, we obtained Rf = 60.5% ±\n4.6%, Rr = 94.5% ± 2.5%, and t_r ≈ 60–70 s at 100°C. The table also lists the\nresidual strain after recovery for each specimen, directly addressing the reviewer’s\nrequest for quasi-plastic behaviour. No sample fractured during programming or\nrecovery (see Table S1 “Shape-memory tests” and Supplementary Movie S5).\nThe moderate Rf (~60%) reflects the relatively dense covalent network (beneficial for\nload-bearing) and the presence of reversible H-bonding. Nevertheless, an Rr ≳ 94%\nwith minute-scale recovery confirms thermally triggered SME. We have retained Fig.\n5c to document room-temperature super-elastic-like cyclic recovery, but now we make\nclear that definitive SME evidence comes from the thermally programmed tests\n(Supplementary Table S2 +Movie S5), not from Fig. 5c.\nFig. R4 SME demonstration.\nIn addition, we have revised the description of Fig. 5c in the main manuscript to clarify\nthat it represents a pseudo-elastic mechanical response (superelastic behaviour) and not\na shape memory cycle. All SME results, including the Rf, Rr, and Tr values and the\nvideo demonstration, have now been moved to a dedicated section in the Supplementary\nMaterials. This separation ensures there is no confusion between the pseudo-elastic\nbehaviour highlighted in Fig. 5c and the genuine SME, which is explicitly demonstrated\nin the supplemental data.\nWe believe these revisions fully resolve the reviewer’s concern by clearly proving the\nmaterial’s SME while properly distinguishing this behaviour from pseudo-elastic\nrecovery. The above changes are implemented in the revision: the Methods section now\nincludes the full SME schedule, statistics, and definitions, and the SI provides the raw\nspreadsheets and the demonstration video link.\nReviewer #4:\nGeneral Comments:\nThe manuscript reports a cellulose-based photo-polymerizable resin for 3D printing\nthat exhibits very promising structural integrity, stress dissipation, and shape-\nmemory behavior. The topic is of interest and the experimental work is substantial.\nOverall, I believe the manuscript could be suitable for publication in Nature\nCommunications after revision. Blow are my detailed comments.\nOur response: We greatly appreciate the reviewer’s positive comments on our\nmanuscript. We are particularly grateful for the recognition of the innovative and\ncontent aspects of our work. We believe the revisions performed address all comments\nthoroughly.\n1. The authors should more clearly place this work in the context of existing 3D-\nprinted shape-memory resins. A dedicated comparison (e.g., table + discussion) to\nrecent reports is required, highlighting the most relevant metrics such as recovery\ntime, recovery ratio, mechanical properties, switching temperature, cycle life, and\nprinting resolution. This will help demonstrate the degree of advancement in a\nquantitative manner.\nOur response: We thank the reviewer for this constructive suggestion. This addition\nallows us to place the present work more clearly in the context of existing 3D-printed\nshape-memory resins and quantitatively highlight the extent of our advances.\nIn accordance with your suggestion, a dedicated comparison Table. R1 (SI Table S6) has\nbeen added, which summarises and compares representative biomass-based and -\nderived 3D-printed shape-memory resin systems reported since 2022. The table\nexplicitly lists the following most relevant metrics: material system, bio-based\nfeedstock, printing method, shape-memory metrics (Rf/Rr/recovery time),\nrepresentative mechanical strength, printing resolution/parameters, cyclic durability,\nand switching trigger (e.g., temperature). Furthermore, we have analysed and discussed\nthese comparisons in the revised support information, and the corresponding table and\ndata have been incorporated into the SI as Table S6. For your convenience, the contents\nof this table are reproduced below:\nTable R1 Comparison of biomass-based and -derived shape memory resins for 3D\nprinting.\nP ol y m er. 3 0 7, 1 2 7 2 5 2, A v a 2 0 2 4 M a cr o m ol. R a pi d C o m m u n. 4 6, 2 4 0 0 6 6 1, A mi n 2 0 2 5 A d v. M at er. I nt erf. 9( 1 6), 2 2 0 0 2 8 0, M a y 2 0 2 2 N - at ur e. 6 2 9, 1 0 6 9 1 2 0 0 7 2 4 4, M a c h a d o N at ur e C o m m u ni c ati o ns. 1 4, 5 5 1 9, Yu e 2 0 2 3 A F M. 3 5, 2 4 1 4 1 2 9, G h os al 2 0 2 5 S ci e n c e A d v a n c es. 1 0, 4 3 8 7, Li 2 0 2 4 T his w o r k\nal\nm\nP ri nti n g m o ul di n\ng\nm et h o d F D M/ F F\nF\nF D M D →\nt\nh\nI\ne\nW\nr\ne st erifi c\nati\no\nn\nD L P/ V P\nP\ng- D L P D L P D L P D L P\nM e c h a ni c al p e rf o r m a n c e ( v r a e l p u r e e ) s e nt ati v e Te nsil e str e n gt h: 4 0. 8 M P a; M ≈ M 8 o P 0 d a 0 u l us U T S 3 5. 9 M P a ( 1 0 % F ₃ O₄ R ) e ; e sili e n c e e n h a n c e m e nt B e n di n g str e n gt h 8 2. 7 8 ± 2. 7 9 M P a; M o d ul us 6. 9 7 ± 0 . 3 8 G P a T ≈ M e 1 P n 7 a s i ; l e str e n gt h M ≈ M 4 o P 7 d a 8 u l us T i ≈ M l e 1 e P n 0 s a s t ; r e n gt h M ≈ a x 3 i m u m m o d ul us M P a T - 3 2 e n sil e str e n gt h: 1 5 M P a; M a xi m u m m o d ul us ≈ G 1 P . a 0 6 C o m p r essi v e st r e n gt h 1 1 5. 4 2 M P a; M o d ul us 1. 4 0 4 G P a; Te nsil e s t r e n gt h 2 5. 1 6 M P a\nS h a p e m e m o r y i n d e x ( Rf/ R r/ti m e) Rf: N ot r e p ort e d; Rr: 9 6 % ( P L A), 9 2 % ＋ ( D P C L P A ) 9 ; 0 T / r P : B N S o 1 t 0 r e p ort e d R ≈ - 9 ( H 7 9 f: % 6 e a N t o & t r e p ort e d; Rr: M a g n eti c); Tr: Aft er f ull y tri g g eri n g, r - 5 - e a c h s > ( 1 9 5 0 % wit hi n 3 2 0 wt % F e 3 O 4) N o n e N o n e R - 9 5 f: % 8 ; 0 / Rr & Tr: T h e vi d e o e x a m pl e d e m o nstr at es t h e r e c o v er y pr o c ess wit h o ut p i f r i o e d v i d d a i n t a g o u n n ti m e or r at e Rf > 7 0 % ( v ari es wit h pr o gr a m mi n g); Rr & Tr: C o m pl et e t h er m al tri g g er r e c o v er y w - 1 0 i 0 t h i n s 4 ( 0 e x a m pl e o p er ati n g c o n diti o n) N o n e R ≈ R ≈ s 6 6 f r 0 0 : : . 9 5 4 4 . % 5 4 ; %; Tr:\nP ri nti n g r es ol uti o n/ p a r a\nm et e rs\nN ot r e p ort e d a n\nd u n a bl e t\no\na dj ust N o n e N o n e 3 0 u m pi x el si z\ne; C a n pri\nnt\n1 0 0 u m w all; 5 0\nu m/l a y er\n5 m 0 l μ e v el N o n e N o n e Mi ni m u m f e at\nu r e ~ 5 µ\nm;\n5 0 µ m/ L a yl a; 8\ns/l a y e r\nC y cl e lif e N o n e N o n e N o n e N o n e 4 0 c y cl es of d ef or m ati o\nn\na n d r e c o v er y T h er e is a l o o p i n t h\ne\ndi a gr a m, b ut n o u nif or\nm\nfr e q u e n c y/r et e nti o n r at e\nis\np r o vi d e d M - c y u cl l e ti st a bilit y St a bl e t h r o u g h m ulti pl\ne\nc o m p r essi o n a n\nd\ns t r et c hi n g c y cl es\nof\nn\ng\nn\ng\n<\n0 of\nS wit c h (t e m p e r at u r e) 7 w 0 a ℃ t er b at h > T _ g; C o m bi n e d eff e ct h e at a n d alt er n ati m a g n eti c fi el d N ot r e p ort e d N ot r e p ort e d C st o ar n t v i ersi o n t ≈ e m 6 2 p / e 4 r 2 a / t ur e: Tc ( t hr e e s yst e ms) N ot e x pli citl y st at e d S wit c h t e m p er at ur e ~ 7 5 ℃ 1 0 0 ℃\nNote: PLA/PBS Biobased blending (FDM; Polymer. 307, 127252, Ava 2024), PLA-\nPBAT/Fe₃O₄ (FDM; Hot/magnetic dual trigger SME) (Macromol. Rapid Commun. 46,\n2400661, Amin 2025), High-content nanocellulose (CA green esterification\ncrosslinking, DIW) (Adv. Mater. Interf. 9(16), 2200280, May 2022), Recyclable\n\"thiolactone\" photoresist (Nature. 629,1069-1074, Machado 2024), Gray scale DLP\ncold programming deformation structure (SMP system, non-biobased) (Nature\nCommunications. 14,5519, Yue 2023), Olive oil-based 4D photosensitive resin (AFM.\n35, 2414129, Ghosal 2025), High toughness shape memory DLP structure (reference\ncontrol, non-biobased) (Science Advances. 10, 4387, Li 2024), This work: Additive\nmanufacturing of cellulose-based photopolymerizable resin with high strength\nand shape-memory. Fused Fiber Manufacturing (FDM/FFF) technology, Ink direct\nextrusion (DIW) extrusion, 3D printing based on grayscale digital light processing (g-\nDLP), Digital Light Processing (DLP). R_f = shape fixity ratio; R_r = shape recovery\nratio; T_r = time required to reach ≥90% recovery; T_sw = triggering/switching\ntemperature (T_g or T_trans); Resolution = reported as the minimum feature size or\npixel/layer thickness available in the cited literature.\nBy placing our work more clearly in the context of existing 3D-printed shape-memory\nresins and comparing it with previously reported 3D-printed shape-memory systems,\nwe can provide a clear, specific, and integrated comparison of the research content and\nconclusions, allowing us to quantitatively demonstrate the extent of the advances\nachieved in this study:\n(1) Comparison of “recovery rate” with FDM (thermally/magnetically triggered)\nsystems: FDM-printed PLA-based SMPs can achieve second-scale recovery under\nexternal thermal or magnetic stimulation. For instance, PLA–PBAT/Fe₃O₄\nnanocomposites reach >90% recovery within 3–4 s in hot-water-triggered tests (15–20 wt% Fe₃O₄),\nachieving ~96–97% R within 58 s under a magnetic field (depending on composition).\nr\nIn contrast, the CPPR resin system developed in this work rebounds spontaneously at\nroom temperature without any external field after an ultrahigh compressive strain of\n75%, restoring both its shape and load-bearing function (strength) within 4–5 min.\nThis “high-load, room-temperature self-recovery” condition is not directly comparable to\nFDM systems, which are mostly triggered above their T . Accordingly, the manuscript\ng\nemphasises the fundamental differences in load level and environmental boundary\nconditions, highlighting the engineering significance of our stress-release-driven self-\nrecovery without external heating.\n(2) Comparison of the “mechanical ceiling” with DIW green-crosslinked\nnanocellulose structural components (SI Table 5): DIW, high-solids-content\nnanocellulose parts employing citric acid (CA) green crosslinking followed by\nesterification can reach a flexural strength and modulus of 82.78 MPa and 6.97 GPa\n(ADMI 2022), respectively, while more recent DIW lignin/nanocellulose composites\nachieve 102.93 MPa/9.05 GPa (ACS Omega 2024). These studies are primarily\npositioned as structural materials (high strength and shape fidelity) and do not\nsystematically report SME metrics. In contrast, the proposed CPPR resin system\nachieves a compressive strength of 115.42 MPa within a photocured network while\nsimultaneously combining high strength, toughness, and recoverability. By using DLP\nprinting, we obtain a single resin system that provides both high mechanical strength\nand complex shape-memory responses, representing an advancement in coupled\nperformance rather than a mere competition in strength or stiffness.\n(3) Comparison of manufacturability/resolution with other sustainable\nphotoresins: The thiolactone-based circular photoresin reported in Nature (2024)\ndemonstrates high-fidelity printing with 30 µm pixels, 50 µm layer thickness, and 100\nµm wall thickness, demonstrating that high resolution and cross-platform\nmanufacturability can be achieved via sustainable chemistry routes. In this work, our\ncustomised DLP setup achieves a minimum feature size on the order of ~5 µm,\ntogether with efficient fabrication at a conventional 50 µm/layer and 8 s/layer. Thus,\nin terms of resolution, our system is on the same order, or even finer in terms of minimum feature\nsize, than these state-of-the-art formulations reported in top-tier journals.\n(4) Recovery mode and temperature window: The distinctive feature of the proposed\nCPPR resin system is the coexistence of: (i) rapid stress-release-driven rebound at room\ntemperature, (ii) high load-bearing capacity and stiffness (compressive strength ≈\n115.42 MPa; E_tensile ≈1.40 GPa), (iii) reproducible printing resolution and process\nparameters (50 μm, 8 s per layer), and (iv) stability in aqueous environments. This\nprofile is complementary to most academically reported thermally triggered SMPs or\nlow-modulus soft networks, e.g., cardanol-based networks, E ≈ 0.2–2 MPa. Our\nCPPR-P maintains a relatively high storage modulus (DMA) in the room-to-medium\ntemperature range (0–100°C), with a Tg of ~90°C, indicating better suitability for\nstructural applications at elevated service temperatures. The results indicate that, under\na “heavy-load, thick-section” condition of 75% compressive strain, the samples can\nfully recover their overall shape within 4–5 min, which is an appropriate recovery\ntimescale for thick, load-bearing components.\nThe olive-oil-based system reported in AFM 2025 exhibits a Tg of around 20–25°C\n(higher Tg₂) and achieves recovery within 40–100 s. It offers advantages in rapid\nresponse for thinner parts in a mild temperature window, rendering it suitable for\nconstrained conditions such as biomedical use. The work published in Nat. Commun.\n2023 provides a cold-programming strategy with multi-stage activatable transitions (Tc\n= 62/42/<0°C), highlighting cutting-edge capabilities in programming freedom and\nmanufacturability of complex architectures. In this context, the proposed CPPR resin\nsystem differs from previous studies in both the application domain and response\nregime and is complementary to them.\n(5) Mechanical benchmarks: In this work, a compressive strength and modulus of\n115.42 MPa and 1.404 GPa, respectively, represent a rare combination of high load-\nbearing capacity and recoverability among bio-based SMPs. For instance, in other\nstudies: the lipoate system reported in Nat. 2024 follows a circular reprinting route and\ndemonstrates a thermal/mechanical window comparable to commercial products, but\ndoes not primarily target SMP metrics; the work published in Sci. Adv. 2024 presents\nextreme stretchability (>1400%), but is not bio-based.\n(6) Printing resolution/complexity (precision): In this work, we have achieved a\nprocess resolution of 5 μm under DLP conditions, facilitated an integrated\ndemonstration of design–fabrication–performance. This resolution contrasts favourably\nwith the highest precision reported in comparative studies (e.g., Nat. 2024), which\ninvolved a systematic evaluation of dimensional deviation and z-direction cure depth\nat a pixel size of 30 μm. This capability highlights that our system is exceptionally well-\nsuited for highly customised, high-precision structural printing. It further suggests that\nthe established pixel/layer-thickness–to–dimensional-accuracy data from those prior\nworks can be leveraged for benchmarking our own high-resolution prints.\nFDM relies predominantly on thermal or magnetic triggering for rapid (second-scale)\nrecovery, but its printing resolution and ability to form complex topologies are\ninherently constrained by nozzle geometry and the layer-by-layer deposition path. DIW\nsystems, while excelling in strength and shape fidelity due to green-crosslinked\nnanocellulose, rarely report key shape-memory effect (SME) metrics. DLP/SLA offer\nadvantages in resolution, complex microstructures, and scalability. Our work\ndemonstrates that, even when biomass is utilised as the primary feedstock, it is still\npossible to achieve strength–shape-memory coupled performance on the same order as\nestablished engineering thermosets.\nFrom the perspective of matching materials, structures, and service conditions, CPPR\nis biased toward higher service temperatures, high load-bearing capacity, and thick-\nwalled components, in contrast with other bio-based systems that have their own\noptimal temperature windows and application scenarios and target in vivo/mild-\ntemperature environments with rapid response. In terms of sustainability, this study\naligns with the closed-loop remanufacturing concept reported in Nature 2024,\nhighlighting the potential for cyclic utilisation of cellulose segments and developing\nrecycle–reprint strategies (e.g., swelling/recovery and possible re-use of chain segments)\nas a promising avenue for future sustainable development.\n2. Recovery time is a key performance index for shape-memory materials. The\nmanuscript should report quantitative recovery data and compare directly with\nstate-of-the-art resins. Please also describe the testing protocol in the Methods\nsection and include appropriate statistics (sample size, mean +/- SD).\nOur response: We thank you once again for raising this point. This is a very\nconstructive suggestion that significantly enhances the scientific rigor and reliability of\nour work. In accord with your recommendation, we have now reported and\nquantitatively benchmarked our recovery data and have performed a comprehensive\ncomparison with state-of-the-art resin systems. In particular, we have addressed this by\nadding a quantitative comparison table (SI Table S6 and Table. R1) and a shape-\nmemory table (Table. R2 below) for representative biomass/biobased SMP systems\nacross multiple printing routes (FDM/DIW/DLP) reported since 2022 (see the table.\nR1 above and the excerpts in Response 1).\nWe have also carried out a detailed comparative analysis of the recovery time, as you\nhighlighted in your comment:\n(1) Comparison of “recovery rate” with FDM (thermally/magnetically triggered)\nsystems: FDM-printed PLA-based SMPs can achieve second-scale recovery under\nexternal thermal or magnetic stimulation. For instance, PLA–PBAT/Fe₃O₄\nnanocomposites achieve >90% recovery within 3–4 s in hot water (15–20 wt% Fe₃O₄),\nas well as ~96–97% Rr within 58 s under a magnetic field. By contrast, the proposed\nCPPR resin system spontaneously rebounds at room temperature without external\nstimuli after an ultra-high compressive strain of 75%, recovering its shape and load-\nbearing function within 4–5 min. This “high-load, room-temperature self-recovery”\ncondition is not directly comparable to FDM systems, which are mostly triggered above\ntheir Tg. Accordingly, the manuscript emphasises the fundamental differences in load\nlevel and environmental boundary conditions, highlighting the engineering significance\nof our stress-release-driven self-recovery without external heating.\n(2) Recovery rate and temperature window: The distinctive feature of the proposed\nCPPR resin system is the coexistence of: (I) rapid stress-release-driven rebound at room\ntemperature, (II) with high load-bearing capacity and stiffness (compressive strength\n≈115.42 MPa; E_tensile ≈1.40 GPa), (III) reproducible printing resolution and\nprocess parameters (50 μm, 8 s per layer), and (IV) stability in aqueous environments.\nThis profile is complementary to most academically reported thermally triggered SMPs\nor low-modulus soft networks, e.g., cardanol-based networks, E ≈ 0.2–2 MPa. Our\nCPPR-P maintains a relatively high storage modulus (DMA) in the room-to-medium\ntemperature range (0–100°C), with a Tg of ~90°C, indicating better suitability for\nstructural applications at elevated service temperatures. These results indicate that,\nunder a “heavy-load, thick-section” condition of 75% compressive strain, the samples\ncan fully recover their overall shape within 4–5 min, which is a reasonable recovery\ntimescale for thick, load-bearing components.\nThe olive-oil-based system reported in AFM 2025 exhibits a Tg of around 20–25°C\n(higher Tg₂) and achieves recovery within 40–100 s. It offers advantages in rapid\nresponse for thinner parts in a mild temperature window, rendering it suitable for\nbiomedical and other constrained environments. The work published in Nat. Commun.\n2023 provides a cold-programming strategy with multi-stage activatable transitions (Tc\n= 62/42/<0°C), highlighting cutting-edge capabilities in programming freedom and\nmanufacturability of complex architectures. In this context, the proposed CPPR resin\nsystem differs from previous studies in both the application domain and response\nregime and is complementary to them.\nIn addition, following your suggestion, we have fully described the testing protocol in\nthe Methods section and included appropriate statistical information (sample size; mean\n± standard deviation). Shape-memory effect (SME) protocol: Printed CPPR resin bars\n(DLP, 50 μm layers; 8 s/layer; 5 base layers at 13 s; 405 nm post-cure 5 min) were\nheated to T_prog = 100°C ~ Tg+10°C (Tg near 90°C by DMA), deformed to a target\nstrain, cooled under load to 25°C, unloaded to obtain the fixed strain (ε_fixed), and then\nreheated to T_sw = 100°C for free recovery. We report Rf and Rr as:\n𝜀 𝜀 −𝜀\nfixed fixed residual\n𝑅𝑓 = ×100%, 𝑅𝑟 = ×100%\n𝜀 𝜀\nmax fixed\nwith n = 5 specimens (reported as mean ± SD) and the recovery time t_r (≥90%\nrecovery).\nBy clearly contextualising our work within existing 3D-printed shape-memory resins\nand comparing it with previously reported systems, we are able to provide a clear,\nspecific, and integrated comparison of the research content and conclusions, thereby\nquantitatively demonstrating the advances achieved. Following these comprehensive\nadditions and revisions, the scientific rigor and readability of the manuscript have been\nsubstantially enhanced.\nTable R2 Shape Memory Test.\nSample Initial Final Applied strain Fixed Shape Shape ≥ 90% Trigger/switch\nname length residual (test gauge strain fixation recovery Recovery temperature\n(L0) plastic length=50 rate (Rf) rate (Rr) time (Ts)\nstrain mm) required\n(Tr)\nn 1 7.00 cm 2% 41.82% 24% 57.39% 91.67% ≈70 s 100 ℃\nn 2 7.00 cm 1% 56.46% 38% 67.30% 97.37% ≈60 s 100 ℃\nn 3 7.00 cm 2% 48.50% 28% 57.73% 92.86% ≈50 s 100 ℃\nn 4 7.00 cm 2% 54.90% 34% 61.93% 94.12% ≈60 s 100 ℃\nn 5 7.00 cm 1% 51.42% 30% 58.34% 96.67% ≈60 s 100 ℃\nAcross five samples and programmed strains, we obtained Rf = 60.5 % ± 4.6 %, Rr =\n94.5 % ± 2.5 %, and t_r ≈ 60–70 s at 100°C. The table also lists the residual strain\nafter recovery for each specimen. No sample fractured during programming or recovery.\n3. Some panels are discussed out of sequence (e.g., Figs. 3 and 4: panel 3g/4e\ndiscussed before 3f/4b). In addition, Figs. 2–4 (compressive, tensile, shear tests)\ncontain repetitive content and could be consolidated into one or two multi-panel\nfigures for clarity.\nOur response: Thank you for your suggestion. This is a very helpful comment that\nsignificantly improves the logical flow and readability of the manuscript. Following\nyour advice, we have revised and corrected the discussion order where previously\ninconsistent (e.g., in Figs. 3 and 4, where panels 3g/4e were discussed before 3f/4b).\nIn addition, we have re-edited and re-ordered the main text (related content of Fig. 3),\nfigure contents, and figure captions to ensure that the discussion sequence and overall\nlogic are now consistent and correct. We have also taken steps to consolidate related\ncontent across these figures where appropriate, thereby improving clarity and reducing\nrepetition (see the revised manuscript for details).\nFig. R1 Fig. 4 before modification in the original manuscript.\nFig. R2 Fig. 4 after modification in the original manuscript.\nAs regards the issue you raised here: “Moreover, Figures 2–4 (compression, tensile,\nshear tests) contain redundant content and, for the sake of clarity, could be combined\ninto one or two multi-panel figures”, we respectfully disagree that this part of the\nmanuscript contains redundant mechanical tests. We therefore provide the following\ndetailed explanation: Although the mechanical performance data in Figs. 2–4 are\nprocessed and plotted in a similar manner, thus exhibiting a certain visual similarity,\nthe underlying data and the physical meaning conveyed by each figure are completely\ndifferent. These plots represent the three most important and classical mechanical\nresponses of structural functional materials: compressive, tensile, and shear properties,\nrespectively. These distinct datasets mutually corroborate and complement each other,\nand together they are essential for demonstrating the superior mechanical performance\nof CPPR-P in this work. At the same time, we have made corresponding revisions and\ndeletions in the relevant parts of the original manuscript.\nFor your convenience and to illustrate the distinct nature of the tests, we have annotated\nall figures and contents that may appear visually similar, and they are presented below:\nFig. R3 (the revised manuscript Fig. 2) Compression mechanical properties.\nFig. R4 Tensile mechanical properties.\nFig. R5 Shear mechanical properties.\n4. The statement in lines 69–72 that “our research group has developed …” appears\nincorrect, as the cited papers seem to be not from the authors’ group. Please review\nthis wording or provide accurate references. A thorough check of the manuscript\nfor similar citation or attribution errors is also necessary.\nOur response: We appreciate the reviewer’s careful reading. You are correct; in the\noriginal text, the placement of the literature citations inadvertently implied that the cited\nworks were from our group. We have corrected this attribution and moved the citations\nat the end of the sentence that actually summarises prior plant cell-wall mechanisms.\nConcretely, the paragraph now reads: “Through bioinspired design that replicates the\nmorphological preservation and stress resilience mechanisms of natural plant cellulose,\nour research group has developed an AM material that simultaneously achieves\nexceptional mechanical strength, rapid-recovery shape memory, and optimal balance\nbetween stiffness and deformability. Since the dawn of human civilisation, the persistent\nobservation and emulation of natural systems have served as a cornerstone for\ncontinuous technological evolution and societal advancement. In plant cell walls, semi-\ndisordered lamellar architectures enable cellulose microfibrils to slide controllably\nthrough dynamic hydrogen-bond rupture and reconfiguration under external\nmechanical stress21-25.”\nThis change removes the citations from the “our research group has developed…”\nsentence and correctly places them to the prior work on cellulose microfibril sliding\n(not to our work). Furthermore, we have performed a thorough, manuscript-wide audit\nto eliminate similar issues. We revised ambiguous phrasing (e.g., replacing like “this\npaper designs …” with neutral, first-person scientific narration such as “In this work,\nwe design …”) and ensured that each citation exclusively supports the statement\nimmediately preceding it. The original location with the problematic wording and the\nrevised context are indicated in the marked section of the Introduction.\n5. The authors attribute the tensile-strength increase after 100 days in water to\n“hydrolysis optimizing the structure.” An alternative explanation could be\nadditional hydrogen bonding or physical rearrangement. To clarify the mechanism,\nthe authors may consider: (1) Providing stronger evidence for hydrolysis (e.g.,\nFTIR, XPS, solid-state NMR, molecular weight analysis, and/or TGA); (2)\nPerforming control immersions in hydrogen-bonding vs. non-hydrogen-bonding\nsolvents and reporting the results; and/or (3) Discussing swelling behavior and\nmass change during immersion.\nOur response: We appreciate the reviewer’s suggestion to clarify the mechanism\nunderlying the tensile strength increase after long-term water immersion and\nsubsequent drying. We performed a comprehensive post-immersion analysis on printed\nCPPR-P parts after 100 days in water and added the results to the SI. Jointly, the data\nsupport a dual-mechanism: limited hydrolytic scission at accessible ester/urethane sites\nplus removal of low-Mw sol fraction, followed by dry-state reinforcement via denser\nH-bonding/rearrangement. This combination rationalises the observed increase in\ntensile strength after drying.\nAdded evidences:\n(1) FTIR (bulk surface, ATR): After 100 days of immersion in water and subsequent\ndrying, the FTIR spectra demonstrated (i) a broadened O–H band (~3200–3600\ncm⁻¹) and (ii) a growth/shift of C=O features (~1700–1730 cm⁻¹) with a shoulder\nconsistent with –COOH/–O–C=O. However, C–O–C intensity (~1150 cm⁻¹) decreased,\nconsistent with mild hydrolysis and formation of more H-bond donors/acceptors in the\nFig.R6 (SI Fig. S21).\nFig. R6 FTIR analysis after immersion in water for 100 days.\n(2) XPS (C1s/O1s deconvolution): The O/C ratio increased, with an enlarged O–C=O\ncomponent (~288.5 eV in C1s; ~532.5 eV in O1s), indicating again the formation\nof new carboxylate/carboxylic groups by hydrolytic cleavage. Adventitious carbon\nwas controlled by identical cleaning/charge-ref settings in the Fig.R7 (SI Fig. S16).\nFig. R7 XPS analysis after immersion in water for 100 days.\n(3) ¹H NMR (solution of extractables): The extractable fraction from aged parts\ndisplayed new low-field methylene signals adjacent to carbonyls (≈2.2–2.5 ppm) and\na reduction of signals attributed to residual acrylate/allylic environments, evidencing\nlow-Mw hydrolysis fragments and further consumption of unreacted moieties in the\nFig.R8 (SI Fig. S17).\nFig. R8 1H NMR analysis after immersion in water for 100 days.\n(4) GPC (extractables): The chromatogram of the post-immersion extract shifted to\nlower Mn/Mw and increased in polydispersity relative to the pristine extract,\nconfirming chain scission in soluble tails/pendant segments while the bulk network\nremained insoluble in the Fig.R9 (SI Fig. S18).\nFig. R9 GPC analysis after immersion in water for 100 days.\n(5) Thermal analysis (DSC/TGA/DTG): After drying, DSC-Tg shifted upward and\nΔC_p across Tg decreased, consistent with reduced segmental mobility and higher\neffective network density. Moreover, TGA (T_5%/T_onset) shifted slightly higher and\nthe low-T mass-loss shoulder was suppressed, indicating removal of volatiles/sol\nfraction and a more thermally stable network. The char yield remained non-zero in N₂,\nas expected for cellulose-derived networks in the Fig.R10 (SI Fig. S19).\nFig. R10 TGA, DTG, and DSC analysis after immersion in water for 100 days.\n(6) Swelling study & mass-change analysis: Following the reviewer’s suggestion,\nwe have performed both a water-swelling study and a hydrolytic mass-loss analysis on\nDLP-printed, fully cured CPPR bars. The new data, including the raw spreadsheets,\nare now provided in the SI as Table S2 (Swelling) and Table S3 (Mass-loss). The key\nfindings are:\nTable R3 Swelling test results and analysis.\nSample Time (h) W0(g) Ws (g) Swelling Does it\nnumber ratio (%) degrade/disintegrate?\nn 1 6 1.11 1.52 36.94 No\nn 2 6 1.49 2.05 37.58 No\nn 3 6 1.26 1.79 42.06 No\nn 4 6 1.24 1.73 39.51 No\nn 5 6 1.50 2.07 38.00 No\nn 1 12 1.11 1.42 27.92 No\nn 2 12 1.49 1.93 29.53 No\nn 3 12 1.26 1.61 27.78 No\nn 4 12 1.24 1.57 26.61 No\nn 5 12 1.50 1.93 28.66 No\nn 1 24 1.11 1.42 27.92 No\nn 2 24 1.49 1.92 28.86 No\nn 3 24 1.26 1.60 26.98 No\nn 4 24 1.24 1.57 26.61 No\nn 5 24 1.50 1.94 29.33 No\nn 1 48 1.11 1.42 27.92 No\nn 2 48 1.49 1.90 27.52 No\nn 3 48 1.26 1.60 26.98 No\nn 4 48 1.24 1.57 26.61 No\nn 5 48 1.50 1.92 28.00 No\nSwelling (DI water, 25°C): The DLP-printed, fully cured CPPR bars exhibit\nmoderate initial water uptake that subsequently plateaus. Across n = 5 specimens per\ntime point, the swelling ratio 𝑆𝑅 = (𝑊 −𝑊 )/𝑊 ×100% was ≈ 37–39 % at 6\ns 0 0\nh, decreasing to a stable ≈ 26–29% at 12-24-48 h. No dissolution or disintegration\nwas observed at any time point up to 48 h. Thus, the DLP-printed specimens reached\nswelling equilibrium within a relatively short time (approximately 12 h). Even when\nimmersed for longer periods, they did not exhibit further water uptake or swelling,\nindicating that a stable state had been achieved.\nTable R4 Mass-loss analysis.\nSample Processing W0(g) W1(g) Mass-loss Mass loss\nNumber conditions rate (%) (g)\n(time/h)\nn 1 48 1.55 1.27 18.06 0.28\nn 2 48 1.37 1.13 17.52 0.24\nn 3 48 1.22 1.02 16.39 0.20\nn 4 48 1.54 1.28 16.88 0.26\nn 5 48 1.53 1.27 16.99 0.26\nHydrolytic degradation (DI water, 25°C, 48 h): After rinsing and drying to constant\nmass, the mass-loss fraction 𝑀𝐿 = (𝑊 −𝑊 )/𝑊 ×100% was ≈17±0.6% (n=5).\n0 1 0\nThis corresponds to removal of low-molar-mass sol fractions and limited ester\nhydrolysis at the network periphery. All specimens remained intact and could be\nhandled without damage.\nThe CPPR-P absorbs water but retains its integrity, reaching a plateau swelling of ≈\n26–29%. This is indicative of a densely crosslinked acrylate–cellulose network with\nlimited free volume. The modest ≈17% mass loss after 48 h reflects the extraction of\nresidual oligomers/sol fractions plus minor hydrolysis of surface ester linkages.\nMoreover, the absence of disintegration corroborates the robust covalent crosslink\ndensity. Together with our mechanical data, these results confirm that CPPR-P is a\nwater-stable, high-strength photoresin suitable for printed parts operating in humid or\naqueous environments. Furthermore, they confirm that the CPPR crosslinked network\nis water-stable (no disintegration) while allowing controlled water uptake, consistent\nwith its covalent network plus reversible H-bonding. The test details have been inserted\nin the Methods section and referenced the new SI tables in the Results.\nWater exposure induces localised hydrolysis at more accessible ester linkages\n(primarily at chain ends/defects), generating –OH/–COOH groups that increase H-\nbond density and facilitate chain packing upon drying. In parallel, leaching of low-\nM_w plasticising species (and minor post-curing) raises Tg and E′, yielding a\nstiffer, stronger network. Thus, the strength increase is not due to wholesale\nbackbone degradation, but to hydrolysis-assisted purification and H-bond\nreorganisation within a stable crosslinked matrix.\nTaken together, these pieces of evidence point to mild hydrolysis plus soluble\noligomer migration, followed by the formation of stronger hydrogen bonding and\nchain rearrangement upon drying, which rationalises the observed increase in\ntensile strength.\nThe corresponding data and discussion have been incorporated into the main\nmanuscript and SI.\n6. In Fig. 3g and the supporting information, TPO appears to be confused with TPU.\nPlease correct.\nOur response: We appreciate the reviewer's diligence in identifying this error. You are\ncorrect—we mistakenly labelled the reaction-condition arrow in Fig. 3g and SI now for\nFig. S15 with “TPU” instead of TPO. We have corrected both labels to “TPO (2,4,6-\ntrimethylbenzoyl-diphenylphosphine oxide), photoinitiator ” and updated the\ncorresponding figure captions. This was strictly a typographical labelling error; the\nexperiments, materials, and analysis consistently used TPO as the photoinitiator at 405\nnm, as correctly stated in the Methods section and in the description of Fig. 3g (TPO-\ndriven photoinitiated polymerisation). Consequently, this correction does not affect the\ndata, interpretations, or conclusions. We have also performed a manuscript-wide audit\nto ensure that “TPU” (thermoplastic polyurethane) appears only where it is intended,\ni.e., as a comparator material in benchmarking plots/movies, and never as a reagent or\nreaction condition. The specific changes are highlighted in the revised files for ease of\nreview and are also listed below.\nFig. R11 The revised Fig.3g in the original manuscript.\nFig. R12 The revised Fig.11 in the original supporting information.\nFig. 3g (main text): The arrow annotation has been corrected from “TPU … ” to\n“TPO (photoinitiator), 405 nm UV, DLP-like exposure conditions”. The caption now\nexplicitly defines TPO and its role in initiating free-radical polymerisation. The\nsurrounding text already states that TPO is the photoinitiator for Fig. 3g. SI Fig. 15\n(Step-3 curing schematic): The reaction-condition label has been corrected to TPO, and\nthe caption updated to state “DLP-based UV curing initiated by TPO”.\nFor absolute clarification: TPO ≠ TPU. TPO is a photoinitiator that undergoes\ncleavage under 405 nm irradiation to generate radicals and initiate double-bond\npolymerisation. TPU (thermoplastic polyurethane) is used in this manuscript solely as\na comparative material for mechanical and shape-memory benchmarking. All curing\nexperiments and interpretations were conducted with TPO as the photoinitiator (not\nTPU), under 405 nm irradiation, consistent with the Methods section and the\ndescription of Fig. 3g. The error was graphical only and has now been corrected. A full\nconsistency check has been completed, confirming that the conclusions remain\nunaffected.\n7. The manuscript contains some repetition and excessive jargon, which reduces\nreadability. Please streamline the text, remove redundancies, define abbreviations\nat first use (e.g., CPPR, HMPR, non-ECPR), and simplify language where possible.\nOur response: This is a very helpful suggestion for improving the manuscript, and we\nthank you for raising it. We carefully reflected on your comment and performed a\ncomprehensive revision of the text.\nFirst, we have re-standardised the nomenclature using a more systematic and\nscientifically sound scheme to improve clarity and reproducibility. In particular, we\nretain CPPR as the main system name and harmonised the other abbreviations to the\nformat “[chemical motif]-PR”, avoiding overly long stacked abbreviations. We also\nintroduced suffixes (L/P) to indicate the physical state of the material. This yields a\ncoherent and readable unified naming/definition scheme across the entire manuscript.\nNow, HMPR is denoted as HEMA-PR (a cellulose-free photocurable resin containing\nonly HEMA) and NE-CPPR is explicitly defined as the non-epoxidised variant of CPPR\n(without the ECH step). Where appropriate, we have added the state suffixes: CPPR-L\n(uncured liquid CPPR resin feedstock) and CPPR-P (DLP-printed CPPR specimens).\nMoreover, ECHMCC is now called MCC-E, referring to MCC molecules grafted via\nECH epoxide ring-opening etherification.\nAll abbreviations are introduced as “full name + abbreviation” at their first\nappearance in the main text and are subsequently used in abbreviated form only. In\naddition, the unified abbreviations are summarised in a dedicated “Abbreviations”\nTable S7 in the SI, and the same terminology is consistently used throughout the text,\nfigures, and captions.\nTable. R5 Summary Table of Abbreviations.\nAbbreviation Abbreviation Full name\nNew name Old name\nCPPR CPPR Cellulose-based photopolymerisable resin precursor\nCPPR-L UC-CPPR Uncured CPPR resin feedstock\nCPPR-P (None) DLP-printed CPPR specimens\nHEMA-PR HMPR Cellulose-free photocurable resin containing only HEMA\nNE-CPPR NE-CPPR Non-epoxidised variant of CPPR (without the ECH step)\nMCC-E ECHMCC MCC molecules grafted via ECH epoxide ring-opening etherification\n8. For all mechanical and shape-memory data, please report sample size (n),\nstatistical measures (mean +/- SD), and test conditions (strain rate, sample\ndimensions, testing temperature). In addition, provide sufficient details on printing\nparameters (resin viscosity, printer model/settings, layer thickness, curing\nconditions) to ensure reproducibility.\nOur response: We have revised the manuscript and SI to provide full statistical\nreporting and reproducibility details as requested.\n(1) Mechanical data (n, mean ± SD, conditions).\nTension, compression, and shear-mechanical tests were conducted on DLP-printed,\nfully cured specimens (dimensions and cross-head speeds/strain rates are now specified\nin the Methods section; testing temperature of 25 ± 0.5°C). An electronic universal\ntesting machine (SHIMADZU AGS-X 10kN) was used to determine the mechanical\nproperties of the AM CPPR samples. The tests included cyclic compression,\ncompressive strength, cyclic tensile strength, tensile strength, and shear performance\nmeasurements. Five replicates were tested per condition, with reported values\nrepresenting averages. Standard dumbbell-shaped specimens where used in the tensile\ntests (thickness: 2 mm; width: 4 mm; gauge length: 50 mm), while in the compression\nand shear tests, rectangular standard specimens (length: 10 mm; width: 10 mm; height:\n25 mm) were used at a displacement rate of 10 mm/min.\nFrom the provided dataset, the cohort statistics are:\nTensile strength: 25.14 ± 1.92 MPa (n = 5).\nCompressive strength: 114.32 ± 13.72 MPa (n = 5).\nShear strength: 24.8 ± 2.3 MPa (n = 5).\n(2) Shape-memory data (protocol, n, mean ± SD).\nAcross five samples and programmed strains, we obtained Rf = 60.5% ± 4.6%, Rr =\n94.5% ± 2.5%, and t_r ≈ 60–70 s at 100°C. The table also lists the residual strain\nafter recovery for each specimen. No sample fractured during programming or recovery.\nMore detailed testing conditions (strain rate, fixation rate, recovery rate, sample size,\ntesting temperature, etc.) have been included into SI Table S1. A demonstration video\nis also included in the SI.\nTable R6 The Shape Memory Test.\nSample Initial Final Applied strain Fixed Shape Shape ≥ 90% Trigger/switch\nname length residual (test gauge strain fixation recovery Recovery temperature\n(L0) plastic length=50 rate (Rf) rate (Rr) time (Ts)\nstrain mm) required\n(Tr)\nn 1 7.00 cm 2% 41.82% 24% 57.39% 91.67% ≈70 s 100℃\nn 2 7.00 cm 1% 56.46% 38% 67.30% 97.37% ≈60 s 100℃\nn 3 7.00 cm 2% 48.50% 28% 57.73% 92.86% ≈50 s 100℃\nn 4 7.00 cm 2% 54.90% 34% 61.93% 94.12% ≈60 s 100℃\nn 5 7.00 cm 1% 51.42% 30% 58.34% 96.67% ≈60 s 100℃\n(3) Printing parameters (reproducibility).\nWe have added a dedicated Printing Parameters table (SI Table S4), which details the\nspecific settings for every resin used (CPPR-L/-L2/-L3, HEMA-PR, NE-CPPR, and\ncomparators UVEP/PA/TPU), including the printing modality, layer thickness, per-\nlayer/base-layer exposure, number of base/buffer layers, z-lift/wait settings, and\nabsolute irradiance at the vat surface. A printer power setting of 100% corresponds to a\nstandard reference irradiance of ≈6.0 mW·cm⁻² for the MiiCraft Ultra 150 3D printer\nused; thus, a setting of 125% corresponds to 7.5 mW·cm⁻².\nThe viscosity of the uncured CPPR-L feedstock is now reported as 168 mPa·s at 25°\nC (rotational viscometer, model, and spindle/speed are stated in the Methods section),\nand the per-resin DLP settings are listed to equalise the cure depth (dose control 𝐸 =\n𝐼 ×𝑡). The printer model, wavelength, and post-cure conditions are given as well. For\nnon-DLP comparators, we have listed the SLS/FDM setpoints to keep benchmarking\nfair and reproducible.\nThese additions meet the journal’s transparency standards and ensure that our\nmechanical and shape-memory results are fully reproducible.\nTable R7 Detailed printing parameters for various types of resins.\nSample Printing Layer Single- Printing Base Buffer Printing Print\nname moulding thickness exposure substrate exposure layer machine (fill)gaps\nmethod (µm) time (s) layers time (s) number power/ (mm)\ntemperature\nCPPR-L DLP 50 8 5 13 5 125% 0.1\nHEMA-PR DLP 50 4 5 10 5 100% 0.1\nNE-CPPR DLP 50 10 5 13 5 125% 0.1\nCPPR-L2 DLP 50 14 5 18 5 150% 0.1\nCPPR-L3 DLP 50 6 5 10 5 125% 0.1\nUVEP DLP 90 2.4 5 8 5 100% 0.1\nPA SLS 150 —— —— —— —— 30 w 0.1-0.2\nTPU FDM 200 —— —— —— —— 200 ℃ 0.1\nNote: Minimum optional Layer thickness of CPPR-L is 5 µm.\nSLS: Selective Laser Sintering\nThe printer power setting of 100% corresponds to a standard reference irradiance of ≈6.0\nmW·cm⁻² for the MiiCraft Ultra 150 3D printer used in our work."}, {"round": 2, "reviewer_comments": {"reviewer_1": "Despite the efforts made by the authors to provide explanation to the raised points in the first review round, several questions still persist that need to be addressed before publication:\nDespite the authors’ efforts to address the points raised during the first round of review, several questions still persist that must be clarified before the manuscript be considered for publication:\n1) In the synthetic protocols, workup details are still missing. How were the final products isolated and recovered from the reaction? How did the authors made sure that the product was pure?\n2) On the “Step 3” the authors wrote that “ethylene glycol dimethacrylate (EGDMA) as a reactive co-monomer (…) and 40 wt% acrylamide (C₃H₅NO) was introduced as a crosslinker.” Please confirm this statement. Why bisacrylamide was added?\nPlease provide this information in the manuscript.\n3) The concerns raised about the confirmation of the functionalization of MCC still persist. How did the 13C NMR add new information? Is it possible to exclude the presence of unreacted HEMA by the NMR results?\n4) Please revise the DS estimation using 1H NMR instead of 13C. 13C signal are not directly proportional to the number of carbons, and for this reason its use should be avoided.\n5) Table 1 is still not sufficient to allow reproduction. What does “monomer” means in the Table? Why is the EGDMA crosslinker still missing?\n6) In Table S4, use standard irradiation units instead of %.\n7) Please provide information about how the .stl file was obtained.\n8) What is the explanation of the authors for the results observed in the swelling tests?\n9) The DSC analysis is still confuse. Adjust the baseline, Which run is presented? Try to perform the test before thermal degradation of the material.\n10) Why deuterated DMSO was used as mobile phase for GPC? Not sure if GPC information is valuable to the present manuscript.", "reviewer_2": "I co-reviewed this manuscript with one of the reviewers who provided the listed reports. This is part of the Nature Communications initiative to facilitate training in peer review and to provide appropriate recognition for Early Career Researchers who co-review manuscripts.", "reviewer_3": "The authors answered the comments appropriately, and no further comments.", "reviewer_4": "I have reviewed the responses and revised manuscript. The authors have sufficiently addressed my previous questions and concerns. The manuscript has improved significantly. I do not have further questions and support its publication in the current form."}, "author_response": "Point-by-point response to reviewers’ remarks\n(Blue: Reviewer’s remarks; Black: Our response)\nReviewer #1:\nGeneral Comments:\nDespite the efforts made by the authors to provide explanation to the raised points in\nthe first review round"}]

Decision letter