Supramolecular coupling of cylindrical micelles following seeded-growth

Domain: chemistry
Published: 2026-02-26
Editorial outcome: major_revision

Abstract
Macromolecular coupling is a widely used technique for industrial materials, while supramolecular coupling is ubiquitous in biological systems. Although the designed synthesis of one-dimensional self-assembled nanostructures via crystallization-driven self-assembly and liquid-crystallization-driven self-assembly has been realized, end-to-end coupling of cylindrical micelles is rarely reported. Unlike crystallization, liquid-crystallization features fluidity under certain conditions. The cylindrical micelles prepared via liquid-crystallization-driven self-assembly possess less organized liquid crystalline blocks at the two partially open ends, originating the end-to-end coupling to lower the free energy. The interaction strength of solvents with liquid crystalline blocks is a pivotal parameter that can be used to switch on or off the coupling. Theoretical simulation is consistent with experimental work, supporting the mechanism. The supramolecular coupling offers opportunities for designing complex polymeric liquid crystalline nanostructures.

Introduction
Covalent coupling refers to the intermolecular reaction of macromolecules, a technique widely used for industrial materials 1-3. On the other hand, supramolecular coupling, though rarely reported, is ubiquitous in natural systems 4. The spontaneous coupling of collagen fibers is one of the essential supramolecular events for their functions 5-9. However, the mechanisms underlying this coupling remain largely unknown and are yet to be explored to empower supramolecular synthesis.

Self-assembly of block copolymers has been developed for controlled synthesis of nanostructures with a high degree of complexity and enhanced functions via crystallization-driven self-assembly (CDSA) 10-16. In CDSA, micelles with crystalline cores exposed to solvents serve as nucleation sites, which induces the crystallization of a second crystalline block copolymer, generating block co-micelles with defined chemical compositions and morphologies 17-22. Notably, the epitaxial growth has also been observed for block copolymers with a liquid-crystallization (LC) block 23-34. The fluidity of liquid crystals, unlike the static state of the crystalline core, allows the rearrangement and ordering of LC blocks within the micelle cores 35-38. This dynamic behavior provides additional pathways for micelle growth and structure design, such as aggregation-fusion growth 24,25,35. In contrast to the epitaxial growth of crystalline copolymers, under certain conditions, the LC block copolymers can form small aggregates first, and then fuse with the LC cores of seeds for growth. The combination of the solvophobicity of LC cores and the subsequent rearrangement of LC blocks drives growth via the fusion of small aggregates 25,36,37, resulting in cylindrical micelles with defined lengths based on the number of seeds used. The fusion can be adjusted by varying the solvent-LC block interactions, as the solubility of LC blocks is a pivotal parameter for the growth 24,29,39,40,41. It is, therefore, possible to drive LC ends to meet, collide, and fuse, after the growth, to realize end-to-end coupling of grown cylinders into nanowires. Each nanowire will contain more than one seed.

Herein, we report the end-to-end coupling of (PBLG-b-PNIPAM) (PBLG: γ-benzyl L-glutamate, PNIPAM: poly(N-isopropyl acrylamide) long cylindrical micelles, forming elongated nanowires. The coupling occurs following the aggregation-growth in solvent systems. As indicated in the theoretical simulation, the LC blocks are not perfectly organized into cholesteric liquid crystals at the ends of cylindrical micelles. T he coupling enables these LC blocks to be reorganized and align with the micelles' internally ordered structures, ultimately stabilizing the linkage. Theoretical simulations indicate that the chain rearrangement process in the coupling, relative to the fusion, involves a larger number of liquid crystal blocks and structural adjustments in both connected cylindrical micelles. This work illustrates the unique capability of liquid-crystallization-driven self-assembly (LCDSA), which complements CDSA and offers possibilities for designing and constructing sophisticated nanostructures with intricate hierarchical features.

Results
Formation of segmented nanowires via end-to-end coupling
Poly(γ-benzyl L-glutamate) (PBLG) is a hydrophobic, rod-like polypeptide with a rigid α-helical conformation. When copolymerized with a hydrophilic coil-like block, such as poly(N-isopropyl acrylamide) (PNIPAM), the resulting rod-coil block copolymers can self-assemble into micelles in selective solvents for the hydrophilic block. Here, PBLG -b-PNIPAM (Fig. 1a, 237 118 subscripts indicate the degree of polymerization) was used for the selective precipitation in tetrahydrofuran/methanol = 45.5/54.5 (v/v), in which tetrahydrofuran (THF) is common solvent and methanol (MeOH) is a selective solvent. The details of polymer synthesis and micelle preparation are provided in Section 1.1 a nd 1.2 of the Supplementary Information (SI). The rationale for choosing the PBLG -b-PNIPAM system is given in Section 1.7 of the SI. 237 118

Transmission electron microscopy (TEM, Fig. 1b) and atomic force microscopy (AFM, Fig. 1c) confirmed the cylindrical morphology. The average length is ~490 nm, and the polydispersity index is 1.10 (Supplementary Fig. 4). The AFM height profile (Fig. 1c, inset) showed a micelle height of ~30 nm. These cylindrical micelles were used as seeds for subsequent seeded growth experiments.

A solution of PBLG -b-PNIPAM in N, N’-Dimethyl Formamide (DMF, 2.0 g/L, 40 μL) 237 118 was added to the seed micelle solution, adjusting the solvent composition to THF/MeOH/DMF = 45/54/1 (v/v/v). DMF, relative to THF, has a better solvation power for PBLG-b-PNIPAM. For seeded growth, we need to prepare a highly concentrated polymer solution to minimize the amount of good solvents in the growth system, so DMF is used. The small amounts of DMF do not affect either micelle growth or coupling; instead, it dissolves well the added copolymer during feeding (Section 1.2 of the SI). When the mixture was incubated for 6 hours, the length of cylindrical micelles increases from ~490 nm to ~1200 nm, as indicated by the TEM image. As shown in the image, the center segment has a broader width than the two flanks (Fig. 1d). It suggests that the growth occurs at two ends of the seeds, and the LC blocks are organized into a narrower LC in the grown segment. Thinner grown segments are likely due to the lower ordering of LC blocks resulting from the growth process in different solvent conditions. After 48 hours, nanowires with lengths up to ~2600 nm are formed and the thin segments of ~15 nm and the broad segments of ~30 nm alternate along the nanowires as indicated i n TEM images (Fig. 1e). The AFM confirms it and reveals the alternative arrangement of the heights of ~15 and ~30 nm (Fig. 1f). It indicates that the segmented nanowires result from the end-to-end coupling of the cylindrical micelles. In addition, based on the difference in width (Supplementary Fig. 5), we can quantitatively analyze these TEM images using the Image-Pro Plus software and automatically identify the seed and grown segments per nanowire.

Based on the experimental results, nanowire formation occurs in two stages: fusion growth and end-to-end coupling. We investigated how varying the unimer-to-seed feed ratio affects this process. To achieve a high feed ratio, we diluted the initial seed solution with the same mixed solvent (THF/methanol = 45.5/54.5, v/v) and then added the copolymer solution (experimental details in Section 1.8 of the SI). As shown in Fig. 1g and Supplementary Fig. 7a, when the feed ratios are 2.0 and 6.0 incubated for 6 hours, the lengths of cylindrical micelles are ~1150 nm (Supplementary Fig. 7a) and ~2700 nm (Fig. 1g), respectively. As expected, the larger the feed ratio, the longer the cylinders. After 48 hours, the segmented nanowires (SEGMENTED) formed regardless of feed ratios (Fig. 1h and Supplementary Fig. 7b). We analyzed the seed (SEED) and grown (GROWN) segments in nanowires, which are distinguished from TEM images. The thick and thin segments in the images represent SEED and GROWN. By analyzing over 200 TEM images using Supplementary Equations (4) and (5), we calculated the average number of SEED per nanowire and the contribution of the GROWN segments to the total length for SEGMENTED. As shown in Fig. 1i, the total length for GROWN (LGROWN) increases linearly with the feed ratio, confirming the complete fusion of added copolymers to seed ends. However, the total length for SEGMENTED does not linearly follow the feed ratios. When the ratio is over 3, the growth of SEGMENTED is retarded (blue line, Fig. 1 i). This is due to the less number of SEED (NSEED) in the SEGMENTED prepared by large feed ratios (Supplementary Fig. 7d), suggesting a less end-to-end coupling. It is reasonable, as a longer GROWN block, resulting from the larger feed ratios, reduced the mobility and thus hindered end-to-end coupling.

Time-dependent dynamic light scattering (DLS) curves for the solution of seeds (in THF/MeOH = 45.5/54.5, v/v), unimers of the block copolymer (in THF/MeOH/DMF = 45/54/1, v/v/v), and the solution that contains seeds and unimers (in THF/MeOH/DMF = 45/54/1, v/v/v) are illustrated in Fig. 2a, 2b, 2c, respectively. In the solution of seeds, the Rh remained unchanged for the first 24 hours, followed by a slight increase after 48 hours (Fig. 2a), suggesting some end-to-end coupling of seeds occurred. The Rh measured from the solution of unimers is ca. 20 nm and remained unchanged over time (Fig. 2b and Supplementary Fig. 9a-b), so the unimers self-aggregated into small aggregates that do not fuse. AFM characterization of these aggregates shows that the height of the small aggregate is ca. 15 nm, which is less than that of the seeds (ca. 30 nm). (Supplementary Fig. 9c-d). The difference between the two solutions is the solvents, which appear to be a factor affecting the dimension of the assemblies.

The DLS curve shows two Rh of 15 nm and 50 nm for the solutions of seeds in the presence of added unimers (Fig. 2c), attributing to the aggregates of added unimers and seeds. Within the first 24 hours, the signal due to small aggregates becomes weaker, and the larger one increases to 56 nm, indicating the occurrence of growth. As aggregates do not fuse, the growth is the fusion of aggregates with seeds (aggregate-seed fusion). At 24 hours, the small aggregates are consumed completely, so no aggregate-seed fusion continues. However, at 48 hours, a DLS curve with a tail at larger Rh values is found, and the average Rh shifts to larger values at 72 hours. This increase in Rh is attributed to end-to-end coupling. The TEM images corresponding to various time points in the DLS curves (Supplementary Fig. 10) further support the fusion growth between seed and small aggregates and the following coupling behavior of the grown micelles. The temporal distributions of NSEED and LGROWN for the 54.0 vol% MeOH condition (Supplementary Fig. 11) indicate that nearly all initial seeds have participated in coupling. The sequential aggregate-seed fusion growth and end-to-end coupling are explained by the mobility of the aggregates and the growing cylinders. The fusion occurs first because it is a relatively faster process. It is attributed to the faster mobility of the small aggregates and the higher possibility for the aggregates to collide with the ends of the seeds. The coupling of two longer cylinders with slower mobility occurs following the fusion process.

As a typical LC polymer, the PBLG adopts an ordered packing structure within the micellar core, resembling a cholesteric LC phase 42,43. Synchrotron radiation wide-angle X-ray scattering (WAXS) was performed to investigate these LC structures. Samples were dried from the solutions for the measurement. The WAXS diffraction pattern of seed micelles (Fig. 2d) showed multiple diffraction rings, indicating ordered nanostructures. Fig. 2e compares the WAXS spectra for seeds, small aggregates of the unimers, and grown micelles. The peak at q = 4.4 nm⁻¹ (d = 1.43 nm) reflected the packing distance between parallel PBLG chains in the micelle core. We also performed using a solution sample, a peak at q = 4.4 nm⁻¹ is also revealed (Fig. 2f), consisting with the measurement using dried samples. Therefore, the LC structures in the solution and after drying are the same. The aggregates have a weaker peak intensity at q = 4.4 nm⁻¹, suggesting a low chain ordering. Upon the growth, the signal is intensified, and diffraction patterns like seeds. It indicates that the fusion growth is driven by LC. PBLG blocks in small aggregates adjust their orientation to match the seed micelles, facilitating the formation of long cylindrical micelles to lower the free energy.

The WAXS results confirmed that ordered packing and chain rearrangement of PBLG blocks drive the growth of cylindrical micelles. To further investigate this process, theoretical simulations were conducted using a coarse-grained model (R C ), where R and C represent the PBLG and PNIPAM blocks, respectively. The interaction strength (ε ) in the Lennard-Jones potential controlled PBLG hydrophobicity, with ε = 2.7ε (ε is the energy unit in the simulation) used to simulate micelle formation (simulation details in Section 2.1 and 2.2 of the SI). The cylindrical seed micelles were first simulated, followed by adding R C copolymers.

At early stages (Fig. 3a-b), the unimers formed small aggregates, some of which fused with seeds. Over time (Fig. 3c), more aggregates fused to the cylinders grown from the seeds, aligning with experimental findings. Notably, end-to-end coupling was absent at this stage. However, as the incubation prolongs to 1.0 × 10⁵ τ (τ is the time unit in the simulation), coupling occurs, forming segmented nanowires (Fig. 3d). Both experiments and simulation indicate that the formation of segmented nanowires involves two sequential processes (Fig. 3i, Supplementary Movie). It starts with Fusion Growth – Small aggregates, which do not have a perfectly ordered LC core, attach to seed ends and adjust their chain alignment to match the cholesteric LC structure of the seeds (Supplementary Fig. 21). This restructuring stabilizes micelle growth. Following this process, End-to-End Coupling occurs – As grown micelles collide, their partially exposed ends act as active sites for coupling (Fig. 3e). The rod blocks in the core at the coupling junction show weak alignment right after the coupling (Fig. 3f). Over time, their orientation adjusts (Fig. 3g-h), resulting in a continuous cholesteric LC structure. This LC-driven self-assembly relies on chain fluidity and rearrangement, though full alignment requires extended time due to the twisting rearrangement of the coupled LC blocks. The fusion growth between a seed and a small aggregate takes ca. 1500 τ for the chains to rearrange, while the coupling of two grown cylindrical micelles takes about 5500 τ (Supplementary Fig. 22).

Solvent effects on micelle growth and coupling
The quality of solvents influences the mobility of LC blocks, thereby affecting micelle growth and coupling. In a THF/MeOH mixture, the methanol content significantly impacts micelle formation. As shown in Fig. 4a-b, increasing the methanol content from 64.3 vol% to 70.6 vol% reduces NSEED in nanowires. At 70.6 vol%, SEGMENTED is minimal, and growth is primarily driven by fusion at seed ends, resulting in long cylindrical micelles (Fig. 4b). As measured from more than 100 samples in TEM images, the SEGMENTED mainly exhibits a seed number of 1 (Fig. 4b, inset). The heights of the grown parts or seed parts remained nearly unchanged with increasing the methanol content (Supplementary Fig. 12).

To quantify this effect, we analyzed the samples taken at specific intervals during the growth in the systems with various methanol contents from 54.0 vol% to 70.6 vol%. For the system with 54.0 vol% methanol, LGROWN grows rapidly to 750 nm in 6 hours and levels off at ~1100 nm after 48 hours. In the first few hours, NSEED is less than 1.5, suggesting that the early-stage growth (within 6 hours) is dominated by fusion growth. Following the growth, the coupling becomes significant, and the NSEED increases to 3.3 at 48 hours. In contrast, when methanol is 70.6 vol%, the final NSEED and LGROWN are only 1.7 (Fig. 4c) and 550 nm (Fig. 4d), respectively, after 48 hours, indicating that both fusion and coupling are retarded at high methanol content. For the other methanol content condition, see Supplementary Fig. 13. The obtained results suggest that a higher methanol content reduces the mobility of LC blocks. In the simulations, the enhancement of the ε (higher methanol content) makes the chain rearrangement more difficult and limits the fusion growth and coupling of micelles (Supplementary Fig. 23), which is consistent with the experimental observation.

To explore solvent effects further, we prepared seed micelles in different initial solvents or selective solvents. In the first case, the common solvent THF was replaced by dioxane (Diox), while in the latter case, the selective solvent methanol was replaced by ethanol (EtOH). The obtained seeds have lengths of ~385 nm and ~760 nm, respectively (Supplementary Figs. 14b, S14d). Then, DMF solutions of the block copolymer (2.0 g/L, 40 μL) were added to these seed solutions for growth.

The growth in the resulting Diox/MeOH/DMF system leads to cylindrical micelles with a length of ~1200 nm (Fig. 5a, Supplementary Fig. 15a). Fig. 5a inset and Fig. 5d (blue line) show that most cylinders have an NSEED of 1.0, suggesting coupling is suppressed when THF is replaced by dioxane. It is attributed to the better solvent-LC block interaction 24,29,44,45, which helps the orderings of PBLG blocks in micelle cores (Supplementary Fig. 16), and thus reduces their possibility for subsequent coupling, which needs space for chain rearrangements.

In contrast, the THF/EtOH/DMF system facilitates the formation of SEGMENTED (Fig. 5b), in which the NSEED reaches 4.0 (Fig. 5b inset, and Fig. 5d, green line). In addition, the LGROWN reaches ~3000 nm (Fig. 5b, Supplementary Fig. 15b), suggesting enhanced fusion growth as well. Since the interaction between the selective solvent ethanol and the LC block is relatively weaker 24,46,47, it could help both growth and coupling. Moreover, compared to the Diox/MeOH/DMF system, the NSEED in the Diox/EtOH/DMF system reaches 3.8 (Fig. 5c inset, and Fig. 5d, purple line). The seed micelles undergo effective growth and end-to-end coupling to form segmented nanowires, confirming that solvent composition regulates chain rearrangement and thus the final nanowire morphology.

Such a solvent-dependent behavior originates from the LC ordering of the PBLG core-forming blocks. Because the end-to-end reactivity is dictated by how readily PBLG chains can rearrange at micelle edges, the solvation environment plays a decisive role. In selective alcohols, methanol solvates PBLG more strongly than ethanol. The weaker solvation of PBLG in ethanol introduces a mild solvophobic drive that facilitates chain mobility and LC reorganization. Consequently, growth and end-to-end coupling occur more efficiently in the THF/EtOH/DMF mixture.

The above experimental observations and simulation reveal the distinct features of LCDSA. Unlike CDSA, the driving force in LCDSA is the formation of LC structures, which do not have restricted crystalline plane matching, and more depends on the fluidity of the LC structure, allowing a dynamic chain rearrangement. This feature endows more kinetic pathways for seeded growth, which means more possible control in nanostructures. For example, due to fusion being mechanically related to the solubility of LC blocks, thereby the chain rearrangement ability can be adjusted by varying the solvent-LC block interactions 24,29. This provides additional control and the potential for modulating the nanostructure. In the present work, a higher methanol content increased the interactions between LC blocks, leading to reduced mobility of the LC blocks and retarding fusion growth. While the better common solvent (e.g., dioxane) helps LC ordering and reduces the possibility of coupling. Conversely, in the selective solvent ethanol, the reduced interaction strength among LC blocks promotes coupling. By changing the solvent, we achieve the regulation of the number of seeds in the nanowires.

End-to-end coupling is not exclusive to LCDSA systems. Examples exist in amorphous and crystallizable polymers through hydrophobic interactions or crystallization-driven aggregation 32,39,48. However, this work not only observed end-to-end coupling in LCDSA systems, but also uncovered how the LC nature of the PBLG core governs the fusion and coupling processes and, critically, how this LC-driven chemistry enables fine-tuning of coupling behavior. Thereby, the present work creates a hierarchically segmented nanowire architecture through a controllable end-to-end coupling mechanism driven by LC chain rearrangement. The segmented nanowires reported here feature alternating thin and thick segments along their long axis — an architecture fundamentally different from previous reported co- micelles or wormlike micelles 32,39,48. The LC-based chain rearrangement is what enables fine control over coupling behavior; by tuning solvent composition, we can modulate this rearrangement and thus adjust the hierarchy of the segmented nanowires. Even when more seed solutions were multiple feeding, it still produced segmented nanowires, but increased the average number of seeds per nanowire from ~3.3 to ~4.5 (Supplementary Fig. 8). This demonstrates that multiple feedings can adjust the hierarchical structure, yet the underlying assembly still proceeds through the exact LC-driven end-to-end coupling mechanism.

In addition, the present work also reveals the relationship between fusion growth and end-to-end coupling behaviors. It was found that when the growth contribution from coupling is excluded, the fusion growth of cylindrical micelles follows the principles of living polymerization. However, the coupling between cylindrical micelles requires more energy to accomplish the chain rearrangement, leading to the growth kinetics deviating from a linear relationship of living growth. This process resembles the termination reaction of two polymerizing polymer chains in free radical polymerization, providing insights for constructing controllable supramolecular reactions by utilizing the polymeric micelle subunits.

Finally, we want to clarify the generality of our strategy, that is, grow through fusion and then undergo LC-mediated end-to-end coupling. A key insight is that LC chain rearrangement — not simply micelle collision — governs whether controlled coupling can occur. Complementing experiments with theoretical simulations, the general rules for achieving controlled LC-driven coupling can be summarized as: 1) LC cores should rearrange more slowly during coupling than during fusion, requiring extended twisting and alignment. 2) The solubility parameters of the LC rod block and coil block should be sufficiently close to allow this rearrangement. 3) A moderate block ratio (e.g., ~2:1 for PBLG 237 -b-PNIPAM 118 ) is needed to balance packing frustration and flexibility. 4) Optimized solvent conditions should allow tunable LC ordering. When these conditions are met, the hierarchical segmented nanowires can form, demonstrating the mechanism's generality.

Methods
Materials. L-Glutamic acid γ-benzyl ester (BLG), ethyl acetate, petroleum ether, sodium chloride, and anhydrous magnesium sulfate were purchased from Adamas-beta. Epoxypropane and triphosgene were purchased from TCLI. N-isopropylacrylamide (NIPAM, 98%, TCI) was purified by recrystallization from n-hexane. 2,2-Azobis(2-Methylpropionitrile) (AIBN, 98%, TCI) was recrystallized from absolute methanol. 2-Aminoethanethiol Hydrochloride (AET·HCl, 95%, TCI) was used without further purification. Methanol (MeOH), Ethanol (EtOH), Tetrahydrofuran (THF), N, N’-Dimethyl Formamide (DMF), and 1,4-Dioxane (Diox) of analytical grade were purchased from Adamas-beta. Deionized water was prepared in a Millipore Super-Q Plus Water System to a level of 18.2 MΩ cm resistance. The dialysis bag (14000 molecular weight cutoff) was provided by Serva Electrophoresis GmbH.

Synthesis of PBLG-b-PNIPAM diblock copolymers. The monomer γ-Benzyl-L-glutamate-N-carboxyanhydride (BLG-NCA) was synthesized by the triphosgene method. Specifically, L-Glutamic acid γ-benzyl ester (BLG, 15 g), epoxypropane (20 mL), and triphosgene (11.7 g) were mixed in 225 mL of tetrahydrofuran. After stirring for 2 h at room temperature, the reaction was quenched with deionized water. The reaction mixture was then sequentially washed with ethyl acetate (150 mL) and saturated brine (200 mL). The organic phase was dried over anhydrous magnesium sulfate. Following the removal of the organic solvent under vacuum, the crude residue was purified by recrystallization in petroleum ether. The synthesis method of the initiator PNIPAM-NH is as follows. AIBN was used as the initiator and AET·HCl as the chain transfer agent to synthesize monoamine-terminated PNIPAM (SPNIPAM-NH 2 ) by free radical polymerization of NIPAM in methanol at 60 °C. The PBLG-b-PNIPAM diblock copolymers were synthesized in anhydrous 1,4-dioxane by ring-opening polymerization of BLG-NCA monomers initiated by the PNIPAM-NH macroinitiator. The reaction was performed in a flame-dried reaction eggplant flask under a dry nitrogen atmosphere at 15 °C for 3 days. After completion of the polymerization, the viscous reaction mixture was poured into anhydrous methanol. The resulting crude residue was dried under vacuum and then purified by recrystallization in methanol to obtain a white solid powder. More synthesis details are given in Section 1.1 of the SI.

Characterizations of PBLG-b-PNIPAM diblock copolymers. The chemical structures and the degree of polymerization (DP) of the block copolymers were measured by the nuclear magnetic resonance spectrometer (1H NMR, Avance 600 MHz, Bruker). The polydispersity (PDI) of block copolymers was determined by the gel permeation chromatography (GPC, PL GPC-50 plus, Varian) measurement. The calibration curve was obtained using narrow polydispersity PBLG polypeptide standards. The characterization details of PBLG-b-PNIPAM diblock copolymers are in Section 1.1 of the SI.

Preparation procedure of seed micelles and segmented nanowires. The seed micelles were prepared through the selective precipitation method. Then, a solution of PBLG-b-PNIPAM copolymers dissolved in DMF (2.0 g/L, 40 μL) was added to the seed solution (4.4 mL, THF/Methanol, v/v, 45.5/54.5). The mixed solution was aged for various incubation times. All incubated solutions were dialyzed against deionized water for at least 3 days to ensure that the organic solvent had been removed before the characterization of aggregate structures. The self-assembly details are given in Section 1.2 of the SI.

Characterizations of assemblies. The morphologies of assemblies were observed by transmission electron microscopy (TEM, JEM-1400, JEOL) operated at an accelerating voltage of 100 kV. The atomic force microscopy (AFM) measurements were performed with an XE-100 (Park Systems) by using the noncontact mode at room temperature in the air. Turbidity measurement was performed to determine the critical methanol content for the aggregation of block copolymers. The optical density (turbidity) was measured at a wavelength of 690 nm with a UV-vis spectrophotometer (UV-2550, Shimadzu). Synchrotron radiation Wide-angle X-ray scattering (WAXS) measurement was performed at beamline BL16B1 of the Shanghai Synchrotron Radiation Facility. The distance from the sample to the WAXS detector was calibrated to 192 mm, and the wavelength of the X-ray was 0.124 nm (E = 10 keV). A two-dimensional WAXS pattern was collected with a Mar165 CCD detector (2048×2048 pixels with a pixel size of 80 μm). The WAXS data were analyzed with the Fit2D software from the European Synchrotron Radiation Facility. The characterization details of aggregates are in Section 1.3 of the SI.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This manuscript from Gao et al. presents a significant advancement in supramolecular polymer science by demonstrating controlled end-to-end coupling of cylindrical micelles via liquid-crystallization-driven self-assembly (LCDSA). The authors combine rigorous experimental characterization with coarse-grained simulations to elucidate a two-stage mechanism (fusion growth followed by coupling) for forming segmented nanowires. This work convincingly establishes LCDSA as a versatile strategy for constructing hierarchical nanostructures. The solvent-dependent tunability of coupling efficiency and the analogy to \"living polymerization with termination\" are particularly compelling. While the study is well-executed and addresses a knowledge gap in supramolecular self-assembly, several issues need to be addressed before publication in Nature Communications.\n1. When feeding the copolymers, the authors used DMF as a good solvent for dissolving the copolymers, while the good solvent used for preparing the seeds was THF. Could DMF affect the growth and coupling of the seed micelles? The role of DMF (as a cosolvent) requires clarification.\n2. In this work, the chain rearrangement of PBLG blocks has been shown to be critical to the growth and coupling of cylindrical micelles. The authors stated, \"full alignment requires extended time due to the twisting rearrangement of the coupled LC blocks\" (Page 11). This statement requires additional simulation or experimental support, specifically regarding the extended time required for chain rearrangement.\n3. When studying the effect of methanol content, the authors state that increasing methanol content enhanced the interaction between the PBLG blocks and reduced their rearrangement capability. Can the simulations provide further valuable information supporting this statement?\n4. The authors investigated the effect of different solvent compositions on the growth and coupling of seed micelles. The initial good solvents include THF and dioxane, while the selective solvents include methanol and ethanol. Apart from the presented results for various solvent combinations, what are the self-assembly, growth, or coupling behaviors in the dioxane/ethanol system?\n5. In Figure 1, the authors should label seed and grown segments directly in TEM images (e.g., Fig. 1d-e) for clarity.\n6. If possible, providing videos of simulation trajectories as Supplementary Movies would help visualize growth and coupling behaviors.\n7. In Section 1.4 of SI, the authors used \"CWC\" to describe the critical methanol content is inappropriate. It should be modified as \"critical methanol content (CMC)\".", "reviewer_2": "The authors synthesized PBLG-b-PNIPAM block copolymers and prepared segmented polymer nanowires by modulating the fusion–growth process and the end-to-end coupling of cylindrical micelles. Unfortunately, end-to-end coupling for hierarchical self-assembly of nanowires has already been reported, and it is fairly clear that block copolymer micelles can form nanowires via end-to-end fusion even in amorphous, non-liquid-crystalline systems. Consequently, attributing end-to-end coupling to “liquid-crystalline properties promoting flow-mediated fusion” does not represent a unique advance. This reviewer is not able to recommend the publication of this manuscript in Nature Communications.\nBelow are a couple of detailed comments:\n1. In Figure 2c, two peaks are observed at early periods. The authors attribute the smaller peak to monomers/seeds and the larger peak to aggregates that form over time. However, DLS can also yield multiple peaks simply because the resulting aggregates possess a broad size distribution. To corroborate their interpretation, the authors should provide corresponding TEM or SEM images recorded at the same time points.\n2. The authors argue that the liquid-crystalline nature of the core accelerates flow-mediated fusion and thus enables end-to-end coupling. Are there, however, any reports of end-to-end coupling in purely amorphous or non-liquid-crystalline systems that would refute this claimed role of the mesogenic ordering?\n3. The authors employed the same material (PBLG₂₃₇-b-PNIPM₁₁₈) to construct both SEGMENTED and GROWN objects. How, then, did they distinguish the two domains?\n4. In Figure 1b, d–e, and g–h, why does the apparent width of the SEGMENTED regions vary markedly?\n5. Furthermore, why do the SEGMENTED lengths reported in Figure 1i differ from those in Figure S4c? A clear and consistent explanation from the authors is required.", "reviewer_3": "The manuscript reports on the end-to-end coupling of cylindrical micelles formed by PBLG-b-PNIPAM block copolymers, giving rise to the creation of nanowire structures. The micelles are composed of two segments; one is crystalline core, and the liquid crystal blocks ends featured by disordered inner segment structures. The fusion between liquid crystal blocks accompanied by inner chain rearrangement process drove the end-to-end couplings. The author conducted various experiments including microscopic (TEM and AFM) observations, DLS, XRD studies, and simulations, which supported authors view. The scientific rational and conducted experiments is rigorous and of good quality. However, some experimental results are unclear due to an absence of detail explanation. Thus, I suggest to consider the manuscript for publication in Nature Communications after a major revision in which the following points have to be appropriately addressed in detail.\n1. Firstly, while I understand that the end-to-end coupling approach is unique, I am not convinced that it is the only possible route to obtaining the observed nanowire structures. The manuscript does not sufficiently explain the novelty of the resulting polymeric architecture. For example, I suspect that even if the seed solutions were added in a stepwise manner, similar nanowire structures might be obtained. The authors should clarify this point. Likewise, the scope and limitations of the present strategy—as well as its generality—should be explicitly discussed. Along this line, I find no clear explanation of why the PBLG-b-PNIPAM block copolymer was chosen for this study. Is this specific structure (or its segmental distribution) indispensable for enabling end-to-end coupling?\n2. For the resulting nanowires, more detailed statistical analyses of the internal structure are required to support the proposed mechanism. While the time-dependent DLS data provide information about the hydrodynamic radius (i.e., overall length), detailed structural insights into the internal organization are lacking. To this end, I feel the analysis of TEM and AFM images is not managed well. A statistically meaningful number of nanowires should be measured both before and after incubation, and each LC segment length should be analyzed in much detail. Such analyses would provide quantitative data on how many seeds (or unimers) were consumed and converted during the elongation process. These quantitative data would confirm that no unreacted seeds’ ends remained prior to adding polymers, which should be critical to work out the supramolecular end-to-end mechanism.\n3. The discussion of several important aspects is overly brief. For instance, the solvent effect investigated in the final part of the manuscript is mentioned only superficially. I can reasonably infer that solvation at the micelle edges influences reactivity, likely due to variations in mobility within the LC domain. However, a more detailed molecular-level discussion seems to be lacking. Which segments in the copolymer are preferentially solvated by the selected solvents? What is induced inside upon changing the polarity (solubility) parameters? In addition, incubation temperature would also influence on the edge reactivity. How the authors optimized these parameters?\n4. The terms such as “crystalline and liquid-crystalline” used for distinction between two parts in the micelle are somewhat ambiguous for non-experts. Related to this, the provided schematic illustration may confuse readers who are not familiar with polymer assemblies. After reading, I understand that the green and purple domains differ in their assembled structures (degree of crystallinity) but are chemically identical. The authors should make this distinction clearer to avoid misinterpretation."}, "author_response": "Responses to Reviewer's comments\nWe thank the reviewers for their careful review of our manuscript and for providing comments and\nsuggestions to improve the quality of the manuscript. Our point-by-point responses to these comments are\ngiven below.\nReviewer #1:\nThis manuscript from Gao et al. presents a significant advancement in supramolecular polymer\nscience by demonstrating controlled end-to-end coupling of cylindrical micelles via liquid-\ncrystallization-driven self-assembly (LCDSA). The authors combine rigorous experimental\ncharacterization with coarse-grained simulations to elucidate a two-stage mechanism (fusion growth\nfollowed by coupling) for forming segmented nanowires. This work convincingly establishes LCDSA\nas a versatile strategy for hierarchical nanostructures. The solvent-dependent tunability of coupling\nefficiency and the analogy to \"living polymerization with termination\" are particularly compelling.\nWhile the study is well-executed and addresses a knowledge gap in supramolecular self-assembly,\nseveral issues need to be addressed before it to be published in Nature Communications.\nComment 1.1 When feeding the copolymers, the authors used DMF as a good solvent for dissolving\nthe copolymers, while the good solvent used for preparing the seeds was THF. Will DMF affect the\ngrowth and coupling of the seed micelles? The role of DMF (as a cosolvent) should be clarified.\nResponse: DMF, relative to THF, has a better solvation power for PBLG-b-PNIPAM. We choose THF for\nseed preparation because DMF leads to irregular aggregates. For seeded growth, we need to prepare a\nhighly concentrated polymer solution to minimize the amount of good solvents in the growth system, so\nDMF is used.\nTo test whether DMF influences micelle growth and end-to-end coupling, we added copolymers\ndissolved in different amounts of DMF into seed solutions. We monitored the assemblies for over 12 h and\n72 h. Despite differences in DMF content, all samples exhibited similar behavior: seeds grew into cylindrical\nmicelles at 12 h. They later coupled into segmented nanowires, with each nanowire containing more than\nthree seeds. These results show that small amounts of DMF do not affect either micelle growth or coupling;\ninstead, it dissolves well the added copolymer during feeding.\nThis information has been incorporated into the revised manuscript (see Line 11-15 of Page 5 in the\nmain text, and Section 1.2 of the Supporting Information, SI).\ncritical to the growth and coupling of cylindrical micelles. The authors mentioned \"full alignment\nrequires extended time due to the twisting rearrangement of the coupled LC blocks\" (Page 11). This\nstatement requires additional simulation or experimental support.\nResponse: We thank the reviewer for this helpful suggestion. Our original statement states that chain\nrearrangement during end-to-end coupling takes significantly longer than that during fusion growth. To\nsupport this, we compared the simulation times required for the two processes. The results indicate that\nthe fusion growth between a seed and a small aggregate takes ca. 1500 τ for the chains to rearrange (Fig.\nR1a). In contrast, the coupling of two grown cylindrical micelles takes about 5500 τ (Fig. R1b). This\nconfirms that chain rearrangement in the coupling step is indeed much slower than in fusion growth.\nFig. R1. The consumed simulation time for chain rearrangements: (a) fusion growth of seed and small aggregate,\n(b) coupling of two contacted grown cylindrical micelles, where τ is the unit of simulation time.\nWe have incorporated the results and discussion into the revised manuscript (see Line 11-13 of Page\n12 in the main text, and Section 2.3 of the SI).\nComment 1.3 When studying the effect of methanol content, the authors mentioned that the increase\nin methanol content enhanced the interaction of the PBLG blocks and reduced the rearrangement\nability. Can the simulations provide more valuable information for this statement?\nResponse: According to the reviewer’s suggestion, we increased the interaction parameter ε in the\nRR\nsimulations, which corresponds to the enhanced interaction of the PBLG blocks at high methanol content\nin the experiments.\nRR\nordered packing manner of chains can be formed in the grown parts and the coupled parts. When the ε\nRR\nis increased to 2.8ε (corresponding to higher methanol content), the fusion growth and end-to-end coupling\ncan still be observed. However, the chain packing manners in the formed nanowires are relatively less\ndisordered. Fig. R2 shows the comparison of the variations in the cosine of orientation angles, φ, along\nthe long axis of coupled micelles formed at 2.7ε and 2.8ε, respectively. At the interaction strength of 2.8ε,\nthe LC chains within the ends of the grown micelles have an imperfect cholesteric LC arrangement, and\nthe chains can not well rearrange themselves after coupling (see Fig. R2b). This result indicates that the\nenhancement of the interaction parameter ε (higher methanol content) makes the chain rearrangement\nRR\nmore difficult and limits the fusion growth and coupling of micelles. This is consistent with the experimental\nobservation.\nFig. R2. Variations in the cosine of φ along the X-axis of the cylindrical micelles obtained at the ε of (a) 2.7ε\nRR\nand (b) 2.8ε. Only the two ends of the grown micelles and their coupled parts are presented in the figures.\nThe above simulation results and discussion provide more information to support our statement\nregarding chain rearrangement ability at high methanol content, which has been incorporated into the\nrevised manuscript (see Line 10-13 of Page 13 in the main text, and Section 2.4 of the SI).\nComment 1.4 The authors investigated the effect of different solvent components on the growth and\ncoupling of seed micelles. The initial good solvents include THF and Diox, while the selective solvents\n3\ninclude MeOH and EtOH. Apart from the presented results of various solvent components, how about\nthe self-assembly, growth, or coupling behaviors in the Diox/EtOH system?\nResponse: As the reviewer suggested, we prepared seed micelles under Diox/EtOH conditions and\nexamined the growth and coupling behaviors of micelles in this solvent condition, where the solvent ratio,\npolymer concentration, and temperatures remain unchanged.\nAt the 45.5/54.5 of Diox/EtOH in volume, the obtained seeds have lengths of ~550 nm (Fig. R3a).\nSubsequently, DMF solutions of the block copolymer (2.0 g/L, 40 μL) were added to these seed solutions\nfor growth. After incubation for 48 hours, the segmented nanowires can be observed in the Diox/EtOH/DMF\nsystem (Fig. R3b). We tracked the variation of the number of seeds (NSEED) per nanowire over time, and\nthe results are shown in Fig. R3c. The NSEED in the Diox/EtOH/DMF system reaches 3.8 (see the solid\ncurve in Fig. R3c). In addition, the total length of grown parts (LGROWN) reaches ~1800 nm. It was found\nthat the micelle growth and coupling in the Diox/EtOH/DMF system are more favorable than those in the\nDiox/MeOH/DMF system. Overall, the Diox/EtOH/DMF system supports growth and coupling even more\nfavorably than the Diox/MeOH/DMF system, confirming that solvent composition regulates chain\nrearrangement and thus the final nanowire morphology.\nFig. R3. (a) TEM image of the seed micelles prepared in Diox/EtOH mixture solution. (b) TEM image of the\nsegmented nanowires prepared in Diox/EtOH/DMF mixture solution after aging at 30 °C for 48 hours. Scale\nbars: 1 μm. (c) Temporal variation of the number of seeds (NSEED) for the Diox/EtOH/DMF system, and the\ncorresponding temporal variations for the other solvent conditions are also plotted for comparison.\nThese contents have been incorporated into the revised manuscript (see Fig. 5, Line 2-6 of Page 15\nin the main text, and Section 1.13 of the SI).\nis suggested for clarity.\nResponse:\nAccording to the reviewer’s suggestion, the seed and grown segments have been clearly labeled in\nthe revised manuscript (see Fig. 1e).\nComment 1.6 If available, provide videos of simulation trajectories as Supplementary Movies to\nvisualize growth and coupling behaviors.\nResponse:\nWe made a video of simulation trajectories as suggested. We provided it as Supplementary Movies\nto visualize growth and coupling behaviors (see the separate file named \"Supplementary Movies\" in the\nrevised version).\nComment 1.7 In Section 1.4 of SI, the authors used \"CWC\" to describe the critical methanol content\nis inappropriate. It should be modified as \"critical methanol content (CMC)\".\nResponse:\nWe recognized that the critical methanol content and its abbreviation in the previous version were\nincorrectly written as \"critical water content (CWC).\" In the revised manuscript, the term has been modified\nto \"critical methanol content (CMC)\" (see Section 1.4 of the SI).\nThe authors synthesized PBLG-b-PNIPAM block copolymers and prepared segmented polymer\nnanowires by modulating the fusion–growth process and the end-to-end coupling of cylindrical\nmicelles. Unfortunately, end-to-end coupling for hierarchical self-assembly of nanowires has already\nbeen reported, and it is fairly clear that block copolymer micelles can form nanowires via end-to-end\nfusion even in amorphous, non-liquid-crystalline systems. Consequently, attributing end-to-end\ncoupling to “liquid-crystalline properties promoting flow-mediated fusion” does not represent a\nunique advance. This reviewer is not able to recommend the publication of this manuscript in Nature\nCommunications.\nComment 2.1 In Figure 2c, two peaks are observed at early periods. The authors attribute the smaller\npeak to monomers/seeds and the larger peak to aggregates that form over time. However, DLS can\nalso yield multiple peaks simply because the resulting aggregates possess a broad size distribution. To\ncorroborate their interpretation, the authors should provide corresponding TEM or SEM images\nrecorded at the same time points.\nResponse: According to the reviewer’s suggestion, we supplemented the TEM images corresponding to\nvarious time points in the DLS curves (Fig. R4a, i.e., Fig. 2c mentioned by the reviewer).\nFig. R4. (a) Temporal evolution of the R of the seed solution containing added copolymer unimers. (b-f) TEM\nh\nimages corresponding to various time points in the DLS curves of (b) 0 hours, (c) 6 hours, (d) 24 hours, (e) 48\nhours, and (f) 72 hours, respectively. Scale bars: 1 μm.\ncontinues, this peak gradually weakens and disappears (red and blue curves in Fig. R4a). TEM images\nconfirm that these aggregates fuse onto the ends of the seed micelles during growth (Fig. R4c, 6 h; Fig.\nR4d, 24 h). After 24 hours, end-to-end coupling becomes dominant, producing segmented nanowires (Fig.\nR4e, 48 h; Fig. R4f, 72 h). At this stage, R increases, and the DLS peaks broaden (green and purple\nh\ncurves). Overall, the TEM observations are fully consistent with the DLS results.\nThe above results and discussion have been incorporated into the revised manuscript (see Line 21-\n22 of Page 8 and Line 1 of Page 9 in the main text, and Section 1.11 of the Supporting Information, SI).\nComment 2.2 The authors argue that the liquid-crystalline nature of the core accelerates flow-\nmediated fusion and thus enables end-to-end coupling. Are there, however, any reports of end-to-end\ncoupling in purely amorphous or non-liquid-crystalline systems that would refute this claimed role of\nthe mesogenic ordering?\nResponse: It is correct that end-to-end coupling is not exclusive to liquid-crystalline systems. Examples\nexist in amorphous and crystallizable polymers through hydrophobic interactions or crystallization-driven\naggregation (Macromolecules 2020, 53, 8581; Polym. Chem. 2023, 14, 2987; Nat. Commun. 2024, 15,\n2968).\nHowever, the significance and novelty of our work do not lie in simply observing end-to-end coupling.\nInstead, our contribution is to uncover how the liquid-crystalline (LC) nature of the PBLG core governs the\nfusion and coupling processes and, critically, how this LC-driven chemistry enables fine-tuning of the\ncoupling behavior.\nIn our system, both fusion growth and end-to-end coupling require LC chain rearrangement, and the\ncoupling step is particularly sensitive to the efficiency of this rearrangement. This provides a robust and\npreviously underappreciated handle: by modulating solvent composition, we can directly influence LC\nordering, thereby controlling growth, coupling dynamics, and ultimately the hierarchical structure of the\nresulting nanowires.\nThus, the key advance of this work is not the occurrence of coupling itself, but the mechanistic insight\nthat liquid-crystalline chemistry offers a precise, tunable pathway to engineer segmented nanowires — an\nopportunity not available in amorphous or non-LC systems. The above discussion has been given in the\nrevised manuscript (see Line 21-22 of Page 16 and Line 1-3 of Page 17 in the main text).\nSEGMENTED and GROWN objects. How, then, did they distinguish the two domains?\nResponse: From the high-magnification TEM image (see Fig. R5), it is clearly observed that there are\nsignificant differences in the widths of the two regions. We analyzed more than 200 TEM images using the\nImage-Pro Plus software and automatically identified the seed and grown segments per nanowire based\non the difference in width.\nAs shown in the image, the thin segments of ~15 nm and the broad segments of ~30 nm alternate\nalong the nanowires. It indicates that growth occurs at the two ends of the seeds, and the LC blocks are\norganized into a narrower micelle core in the growing segment. Thinner grown segments are due to the\nlower ordering of LC blocks in different solvent conditions.\nFig. R5. High-magnification TEM image of segmented nanowires. Scale bars: 1 μm.\nFor clarity, we labeled the seed and grown segments directly in TEM images and provided the\nidentification details in the revised manuscript (see Fig. 1e, Line 22-23 of Page 5, Line 2-4 of Page 6 in the\nmain text, and Section 1.6 of the SI)\nComment 2.4 In Figure 1b, d–e, and g–h, why does the apparent width of the SEGMENTED regions\nvary markedly?\nResponse: We thank the reviewer for pointing this out. The scale bar in Fig. 1e (the enlarged TEM image)\nwas indeed inconsistent with that in Fig. 1f. In the revised manuscript, we have corrected the scale bar in\nFig. 1e and rechecked all figures to ensure consistency (see the updated Fig. 1e and caption).\nin Figure S4c? A clear and consistent explanation from the authors is required.\nResponse: We appreciate the reviewer’s attention to this point. The SEGMENTED lengths in Fig. 1i and\nFig. S4c in the previous version appear different because they come from different experimental batches\nand serve different purposes.\nFig. 1i reports the final SEGMENTED lengths measured after 72 hours at various unimer-to-seed\nratios, while Fig. S4c shows the time-dependent evolution of SEGMENTED lengths during the growth\nprocess.\nWhen we compare only the data collected under the same conditions (72 hours and identical unimer-\nto-seed ratios), the values in Fig. 1i and Fig. S4c agree very well. For example, at ratios of 2, 3, and 5, the\nfinal lengths are 2.63 ± 0.13 μm, 3.12 ± 0.20 μm, and 4.37 ± 0.22 μm in Fig. 1i, which match the\ncorresponding values of 2.60 ± 0.13 μm, 3.13 ± 0.18 μm, and 4.28 ± 0.12 μm in Fig. S4c. The small\ndifferences fall within normal statistical variations.\nWe have added the numerical comparison and a brief explanation of this consistency in the revised\nSupporting Information (see Section 1.8 of the SI).\nThe manuscript reports on the end-to-end coupling of cylindrical micelles formed by PBLG-b-\nPNIPAM block copolymers, giving rise to the creation of nanowire structures. The micelles are\ncomposed of two segments; one is crystalline core, and the liquid crystal blocks ends featured by\ndisordered inner segment structures. The fusion between liquid crystal blocks accompanied by inner\nchain rearrangement process drove the end-to-end couplings. The author conducted various\nexperiments including microscopic (TEM and AFM) observations, DLS, XRD studies, and simulations,\nwhich supported authors view. The scientific rational and conducted experiments is rigorous and of\ngood quality. However, some experimental results are unclear due to an absence of detail explanation.\nThus, I suggest to consider the manuscript for publication in Nature Communications after a major\nrevision in which the following points have to be appropriately addressed in detail.\nComment 3.1 Firstly, while I understand that the end-to-end coupling approach is unique, I am not\nconvinced that it is the only possible route to obtaining the observed nanowire structures. The\nmanuscript does not sufficiently explain the novelty of the resulting polymeric architecture. For\nexample, I suspect that even if the seed solutions were added in a stepwise manner, similar nanowire\nstructures might be obtained. The authors should clarify this point.\nResponse: We thank the reviewer for this critical comment. We want to clarify that the novelty of our work\ndoes not lie in producing nanowires per se, but in creating a hierarchically segmented nanowire\narchitecture through a controllable end-to-end coupling mechanism driven by liquid-crystalline (LC) chain\nrearrangement.\nThe segmented nanowires reported here feature alternating thin and thick segments along their long\naxis — an architecture fundamentally different from previously reported co-micelles or wormlike micelles\n(Nat. Commun. 2024, 15, 2968; Macromolecules 2020, 53, 8581; Polym. Chem. 2023, 14, 2987). Their\nformation relies on the liquid-crystallization-driven self-assembly (LCDSA) mechanism: growth first\nproceeds through the fusion of small aggregates, followed by LC-mediated end-to-end coupling, which\nrequires substantial chain rearrangement. This LC-based chain rearrangement is what enables fine control\nover coupling behavior; by tuning solvent composition, we can modulate this rearrangement and thus\nprecisely adjust the hierarchy of the segmented nanowires.\nTo address the reviewer’s question regarding stepwise seed addition, we performed an additional\ncontrol experiment. Adding more seed solution after 24 hours still produces segmented nanowires, but\n10\nincreases the average number of seeds per nanowire from ~3.3 to ~4.5 (Fig. R6). This demonstrates that\nmultiple feedings can adjust the hierarchical structure, yet the underlying assembly still proceeds through\nthe exact LC-driven end-to-end coupling mechanism.\nIn summary, while segmented structures could, in principle, form under different feeding strategies,\nthe key novelty of our work lies in uncovering and exploiting the LC-driven chemical mechanism that\nenables the controllable and tunable formation of hierarchical segmented nanowires — an advance not\navailable in amorphous or non-LC systems.\nFig. R6. Schematic illustration and representative morphology of segmented nanowires prepared by stepwise\naddition of seed. Scale bars: 1μm.\nTo provide a profound understanding of end-to-end coupling, we have incorporated the above results\nand discussion into the revised version (see Line 3-13 of Page 17 in the main text, and Section 1.9 of the\nSupporting Information, SI).\nComment 3.2 Likewise, the scope and limitations of the present strategy - as well as its generality-\nshould be explicitly discussed. Along this line, I find no clear explanation of why the PBLG-b-PNIPAM\nblock copolymer was chosen for this study. Is this specific structure (or its segmental distribution)\nindispensable for enabling end-to-end coupling?\nResponse: We appreciate the reviewer’s insightful comments. Below, we clarify both the generality of our\nstrategy and the rationale for choosing the PBLG-b-PNIPAM system.\nOur work reveals a liquid-crystallization-driven self-assembly (LCDSA) mechanism in which\nmicelles first grow through fusion and then undergo LC-mediated end-to-end coupling. A key insight is that\nLC chain rearrangement — not simply micelle collision — governs whether controlled coupling\ncan occur. By tuning solvent composition or temperature, we can regulate this rearrangement ability and\nthus adjust the hierarchical segmented structures. This mechanistic understanding, rather than the mere\n11\nexistence of coupling, is the main novelty and significance of the study.\nTo assess generality, we complemented experiments with theoretical simulations. These simulations\nrevealed general design rules for achieving controlled LC-driven coupling:\n1. LC cores should rearrange more slowly during coupling than during fusion, requiring extended\ntwisting and alignment.\n2. The solubility parameters of the LC rod block and coil block should be sufficiently close to allow\nthis rearrangement.\n3. A moderate block ratio (e.g., ~2:1 for PBLG -b-PNIPAM ) is needed to balance packing\n237 118\nfrustration and flexibility.\n4. Optimized solvent conditions should allow tunable LC ordering.\nWhen these conditions are met, the hierarchical segmented nanowires can form, demonstrating the\nmechanism's generality.\nWe also tested other LC-containing block copolymers. For example, PBLG -b-PEG failed to\n226 112\nproduce segmented nanowires in either THF/MeOH/DMF or Diox/MeOH/DMF, yielding only irregular fibers\nor cylinders (Fig. R7). This is consistent with the design rules: PEG is far more hydrophilic, and its solubility\nmismatch with PBLG prevents the necessary LC rearrangement.\nFig. R7. (a,c) TEM images of seed micelles prepared by PBLG -b-PEG copolymers in (a) THF/MeOH and\n226 112\n(c) Diox/MeOH solutions. (b,d) TEM images of aggregates after feeding PBLG-b-PEG copolymers and aging at\n30 °C for 48 hours in (b) THF/MeOH/DMF and (d) Diox/MeOH/DMF solutions. Scale bars: 1 μm.\nHansen solubility parameters, and the THF/MeOH/DMF solvent combination provides the right balance for\nLC ordering and rearrangement. Therefore, the choice of PBLG -b-PNIPAM is not arbitrary — it is\n237 118\nessential for enabling the controllable LC-driven coupling process.\nThese clarifications and supporting data have been incorporated into the revised manuscript (see Line\n4-5 of Page 5 and Line 1-11 of Page 18 in the main text, and Section 1.7 of the SI).\nComment 3.3 For the resulting nanowires, more detailed statistical analyses of the internal structure\nare required to support the proposed mechanism. While the time-dependent DLS data provide\ninformation about the hydrodynamic radius (i.e., overall length), detailed structural insights into the\ninternal organization are lacking. To this end, I feel the analysis of TEM and AFM images is not\nmanaged well. A statistically meaningful number of nanowires should be measured both before and\nafter incubation, and each LC segment length should be analyzed in much detail. Such analyses would\nprovide quantitative data on how many seeds (or unimers) were consumed and converted during the\nelongation process. These quantitative data would confirm that no unreacted seeds’ ends remained\nprior to adding polymers, which should be critical to work out the supramolecular end-to-end\nmechanism.\nResponse: We thank the reviewer for this important suggestion. In response, we have performed a more\nsystematic and quantitative analysis of TEM images throughout the entire incubation period to support the\nproposed LCDSA mechanism directly.\nFirst, we supplemented TEM images at all key time points corresponding to the DLS measurements\n(Fig. R8). At 0 hours, small aggregates are clearly visible, matching the small DLS peak. As incubation\nproceeds, these aggregates progressively disappear, and TEM images show that they are consumed\nthrough fusion growth at the open seed ends (6 h and 24 h). After 24 hours, end-to-end coupling becomes\ndominant, and segmented nanowires appear (48 h and 72 h), consistent with the broadening R distribution\nh\nin DLS. Thus, the structural evolution observed by TEM and DLS is fully correlated.\nTo provide statistically meaningful evidence, we quantified the temporal distributions of seed number\n(NSEED) and grown length (LGROWN) for the 54.0 vol% MeOH condition (Fig. R9). Early in incubation (<6 h),\nmost structures contain only 1–2 seeds, reflecting fusion growth. By 24 h, NSEED increases to 3–4, and by\n48 h it stabilizes at ~4, indicating that nearly all initial seeds have participated in coupling, with no\n13\nunreacted ends remaining. LGROWN also increases rapidly within 6 h and narrows with time, confirming a\ntransition from growth to controlled coupling.\nFig. R8. (a) Temporal evolution of the R of the seed solution containing added copolymer unimers. (b-f) TEM\nh\nimages corresponding to various time points in the DLS curves of (b) 0 hours, (c) 6 hours, (d) 24 hours, (e) 48\nhours, and (f) 72 hours, respectively. Scale bars: 1 μm.\nFig. R9. Temporal variations of (a) the seed number NSEED and (b) the LGROWN for the segmented nanowires\nformed at methanol contents of 54.0 vol%.\narise not from random aggregation, but from a time-resolved LC-driven sequence of fusion followed by\ncontrolled end-to-end coupling, enabled by LC rearrangement at partially open ends. The absence of\nunreacted seeds at later stages further confirms that the coupling process is systematic and governed by\nthe LC ordering principles revealed in this work.\nAll additional analyses and discussions have been included in the revised manuscript (see Line 21-\n22 of Page 8 and Line 1-3 of Page 9 in the main text, and Section 1.11 of the SI).\nComment 3.4 The discussion of several important aspects is overly brief. For instance, the solvent\neffect investigated in the final part of the manuscript is mentioned only superficially. I can reasonably\ninfer that solvation at the micelle edges influences reactivity, likely due to variations in mobility within\nthe LC domain. However, a more detailed molecular-level discussion seems to be lacking. Which\nsegments in the copolymer are preferentially solvated by the selected solvents? What is induced inside\nupon changing the polarity (solubility) parameters? In addition, incubation temperature would also\ninfluence on the edge reactivity. How the authors optimized these parameters?\nResponse: We thank the reviewer for the insightful comments. We agree that a deeper discussion of\nsolvent effects and incubation temperature is essential for understanding the molecular basis of micelle\ngrowth and end-to-end coupling. These considerations were indeed integrated into our study, and we now\nprovide a more detailed explanation to clarify the underlying mechanism and highlight the novelty of our\nwork.\n1) Molecular-level solvation effects\nThe solvent-dependent behavior originates from the liquid-crystalline (LC) ordering of the PBLG core-\nforming blocks. Table R1 summarizes the Hansen solubility parameters of PBLG, PNIPAM, and the\nsolvents used. Because the end-to-end reactivity is dictated by how readily PBLG chains can rearrange at\nmicelle edges, the solvation environment plays a decisive role.\nIn selective alcohols, methanol (δ = 30.20 MPa1/2) solvates PBLG more strongly than ethanol (δ =\n26.60 MPa1/2). The weaker solvation of PBLG in ethanol introduces a mild solvophobic drive that facilitates\nchain mobility and LC reorganization. Consequently, growth and end-to-end coupling occur more efficiently\nin the THF/EtOH/DMF mixture, consistent with our experimental results (see Fig. R3c and Fig. 5 in the\nrevised manuscript). By explicitly incorporating these solubility considerations, we clarify how solvent\n15\nidentity controls segment rearrangement and thus the kinetics of fusion and coupling. These analyses\nstrengthen the molecular-level foundation of the proposed mechanism.\nTable R1. Hansen solubility parameters of PBLG, PNIPAM, and solvents\nSample Hansen solubility parameters δ / MPa1/2\nPBLG 23.40\nPNIPAM 23.50\nDMF 24.90\nTHF 19.50\nDiox 20.47\nMeOH 30.20\nEtOH 26.60\n2) Optimization of incubation temperature\nTemperature also modulates chain mobility within both the LC core (PBLG) and corona (PNIPAM),\nthereby regulating edge reactivity.\n• At 20 °C, the LC blocks possess insufficient mobility. Chain rearrangement is strongly hindered,\nand only one or two segments form even after 48 h (Fig. R10a).\n• At 40 °C, PBLG mobility increases, but PNIPAM chains collapse more tightly around the core,\nparadoxically restricting PBLG rearrangement and suppressing growth and coupling (Fig. R10b).\n• At 30 °C, both PBLG and PNIPAM retain adequate mobility. This balanced condition uniquely\npermits efficient fusion growth followed by controlled end-to-end coupling, as confirmed by the\nevolution of NSEED (Fig. R10c).\nThese results demonstrate that precise thermal control is critical for enabling the LC-mediated\nrearrangement required for segment fusion, and they reinforce the central novelty of this work: the coupling\nbehavior is not simply dictated by end-to-end contact. Still, it emerges from tunable LC chemistry at micelle\nedges.\nFig. R10. TEM images of the aggregates after incubating at (a) 20 °C and (b) 40 °C for 48 hours. (c) Variations\nof the seed number NSEED for the segmented nanowires formed at various temperatures. Scale bars: 1 μm.\nof Page 16 in the main text, and Section 1.13 and 1.14 of the SI).\nComment 3.5 The terms such as “crystalline and liquid-crystalline” used for distinction between two\nparts in the micelle are somewhat ambiguous for non-experts. Related to this, the provided schematic\nillustration may confuse readers who are not familiar with polymer assemblies. After reading, I\nunderstand that the green and purple domains differ in their assembled structures (degree of\ncrystallinity) but are chemically identical. The authors should make this distinction clearer to avoid\nmisinterpretation.\nResponse: We thank the reviewer for this suggestion. In the revised manuscript, when describing the\ndifferences between the seeds and the grown segments, we emphasize that their chemical composition is\nthe same (both are formed from PBLG-b-PNIPAM copolymers), but their structures differ. For clarity, we\nadded a label to the Schematic illustration in Fig. 3i to distinguish between the seeds and the grown\nsegments (see Fig. R11).\nFig. R11. Schematic illustration of (I) Fusion growth and (II) Coupling behaviors via LCDSA, where green and\nblue objects represent the micelle seed, the grown and coupled segment with different degrees of LC ordering.\nThe above content has been incorporated into the revised version (see Fig. 3i and its caption).\n17"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have fully addressed all my concerns. The manuscript is ready for publication now.", "reviewer_2": "It is worth noting again that end-to-end coupling of cylindrical micelles has already been reported in living CDSA systems (e.g. liquid crystalline block copolymer: Macromolecules 2021, 54, 6845−6853; Nature Communications, 2024, 15, 2968; crystalline-coil block copolymer: J. Am. Chem. Soc. 2011, 133, 11220-11230), and investigations on end-to-end supramolecular assembly of cylindrical micelles have been more intensively published. The authors only (partially) addressed the technical issues, but failed to elevate the basic novelty of this work. Thus, this reviewer strongly feel that it is not suitable for a high-tier journal like Nature Communications.", "reviewer_3": "The authors have done an excellent job of addressing all my comments, as well as those from the other reviewers, in a detailed and satisfactory manner. They have made appropriate changes to both the main manuscript and the Supplementary Information accordingly. In addition, they have carried out a series of new experiments and theoretical simulations, all of which have contributed to improving and clarifying the content of the paper. I sincerely appreciate the authors’ careful revisions. In my opinion, all the points raised by the reviewers have been clearly addressed, and the revised manuscript is now suitable for publication in Nature Communications.\nI would like to congratulate the authors on their conceptually insightful and well-executed work."}, "author_response": ""}]

Decision letter