Self-growth of programmable 2D- and 3D-coupling responsive coating for anti-counterfeiting

Domain: chemistry
Published: 2025-12-23
Editorial outcome: major_revision

Abstract
Programmable dual-mode (two or three dimension, 2D/3D)-coupling responsive coating constitutes one of the most promising strategies to ensure the security of anti-counterfeiting and information encryption, but it is still lack of effective approaches to integrate stimuli-responsive 2D and 3D information. Herein, we develop a self-growing method to achieve this purpose based on photoswitchable fluorescence and supramolecular interaction (dipole-dipole interaction) toward advanced multi-dimensional anti-counterfeiting and encryption. In our method, trifluoromethyl-rich monomers (2,2,2-trifluoroethyl methacrylate (TFEMA) and 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA)), polymerizable green fluorescent dye (2-(6-(dimethylamino)−1,3-dioxo-1H-benzodeisoquinolin-2(3H)-yl)ethylacrylate, MNEA) and photochromic diarylethene derivative (4-(acryloyloxy)butyl-4-(2-methyl-3-(2-(2-methylbenzothiophen-3-yl)−4-oxo-5,6-dihydro-4H-thieno2,3-thiopyran-3-yl)benzothiophen-6-yl)−4-oxobutanoate, BTBA) are introduced into specific 3D structure via a self-growing method. The coating is capable of reversible fluorescence switching from green to red through photo-induced fluorescence resonance energy transfer (FRET) process between MNEA and BTBA, and reversible switch of 3D structure based on force- and thermo-induced shape memory caused by dipole-dipole interaction and covalent bond. Interestingly, when the 2D information is stimulated, the 3D information remains unchanged. Several examples demonstrate that the great application potential of the programmable responsive coating in high-security of multilevel anti-counterfeiting and information encryption. We thus envision the great potential of our method in developing advanced anti-counterfeiting, multi-level information encryption and high-density data storage.

Introduction
Counterfeiting is a serious global social problem involving many industries, which can cost the worldwide economy over 500 billion annually. Many counterfeiting technologies were developed to ensure economic security and prevent the serious social problems caused by counterfeit information. These technologies generally included the complanate two-dimensional information (2D, Fig. 1a), and surface texture (3D, Fig. 1a). 2D technologies mainly depended on fluorescent and color coating based on optical pattern, watermark, QR code, bar code, and so on. Recently, many stimulus-responsive coatings that can regulate their optical signal (i.e., fluorescence, color) through external stimuli (i.e., light, temperature, force, ions, pH and humidity) have been developed for improving the security of these anti-counterfeiting technologies. Among these, photoswitchable fluorescence coatings with high resolution and easy identification, which can achieve reversible fluorescence switching under the alternately irradiation of different light, have been applied in creating various advanced anti-counterfeiting systems. Meanwhile, 3D-encoding strategy like surface texture is another powerful method by using reflecting light to show real 3D image (holography) or utilizing surface texture to encode information directly (Fig. 1a). 3D-encoding strategies thus have gained widespread attention because of some excellent features, including tunable properties, 3D topography, and hard-to-forge, and thus applied in the development of anti-counterfeiting systems. Although reported 2D- and 3D-encoding strategies exhibit some inherent advantages, and applied to banknotes, passport and high-end packaging, they can only offer single-dimensional anti-counterfeiting and encryption protection, which put them at risk of being forged because of single functionality and low information-bearing dimension. Therefore, the imperfection of 2D- or 3D-encoding strategy has encouraged researchers to try to couple them into one system to significantly improve security performance.

Natural systems are masters in coupling 2D color and 3D structures for camouflage. Like Tokay geckos, they can achieve desired camouflage by specifically integrating 2D color and 3D structure on their backs (Fig. 1b), in which the 2D and 3D information are on-demand combined to significantly enhance their security, suggesting an advanced anti-counterfeiting technology. Recently, several attempts have been conducted to mimic such a combination of 2D and 3D technologies to develop high-performance anti-counterfeiting and encryption systems. However, those 2D and 3D information are simply mixed rather than being coupled on demand. They are still far from on-demand coupling that allow for independent manipulation of 2D and 3D information, due to the lack of the effective integration mechanism of incorporating functionalized molecules to functionalize 3D structures. Obviously, programmatically coupling responsive 2D and 3D information like natural systems still remains challenging. In contrast, bio-inspired self-growing method is a promising strategy for constructing programmable 3D structures and on-demand coupling responsive 2D and 3D information. In this strategy, polymerizable functional monomers (nutrients) are firstly pre-stored in substrates (act as seeds), and then generated on-demand 3D structures by using photo-induced cascade reactions including polymerization for forming polymer networks and chain exchange reactions to eliminate internal stress caused by growth between 3D structures and substrates. Compared with the traditional methods (i.e., imprinting methods), bio-inspired self-growing method also shows several advantages: (1) easily coupling different functional monomers into the user-defined location to creating specific structures with orthogonal multi-stimulus response; (2) post-modifying some functions that cannot be introduced by direct synthesis or imprinting methods.

Herein, we use a self-growing method to prepare programmable 2D/3D-coupling responsive coatings constructed via dynamic interaction (dipole-dipole interaction), toward multi-dimensional anti-counterfeiting and information encryption. In our design, the initiated substrates (seeds) are prepared via free radical polymerization of trifluoromethyl-rich monomers (2,2,2-trifluoroethyl methacrylate (TFEMA) and 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA)), and a crosslinker (hexamethylene diacrylate, HDDA). Polymerizable green fluorescent dye (2-(6-(dimethylamino)−1,3-dioxo-1H-benzodeisoquinolin-2(3H)-yl)ethylacrylate, MNEA) and photochromic diarylethene derivative (4-(acryloyloxy)butyl-4-(2-methyl-3-(2-(2-methylbenzothiophen-3-yl)−4-oxo-5,6-dihydro-4H-thieno2,3-thiopyran-3-yl)benzothiophen-6-yl)−4-oxobutanoate, BTBA) are integrated into the seeds to fabricate 2D/3D-coupling responsive coating by using a self-growing method and subsequently benzenesulfonic acid (BSA)-induced transesterification for chain exchange. In this system, photo-induced fluorescence resonance energy transfer (FRET) process between MNEA and BTBA would ensure fluorescence information (2D) to reversibly switching between green and red. Thermo- and force-induced reversible change of dipole-dipole interaction would induce a reversible switching in 3D information. Overall, comparing with previous stimuli-responsive coating for anti-counterfeiting, programmable 2D/3D-coupling responsive coating shows multiple advantages: (1) the responsive 2D and 3D information are programmatically coupled into the user-defined location; (2) the coupled responsive 2D and 3D information can be reversibly and independently switched; (3) growth-induced self-healing can facilitate the preparation of complex user-defined structures for their applications in advanced anti-counterfeiting and information encryption. Thanks to advanced features including high fluorescence contrast, responsiveness, and excellent reversibility, we thus can demonstrate the programmable responsive coating in high-security of multilevel anti-counterfeiting and information encryption. These results indicate that this strategy offer an opportunity for developing multi-mode anti-counterfeiting and encryption materials.

Results
Anti-counterfeiting coating design
Our dual-modal (2D/3D) encryption strategy was demonstrated through combining the self-growing method and dynamic interaction (dipole-dipole interaction) to prepare programmable 2D/3D-coupling responsive coatings (Fig. 1c). The self-growing method, capable of in situ post-modulating the structure and properties of existed samples or on-demand integrating functional monomers into prepared samples, represents a desired method for developing orthogonal multi-stimulus response functional materials or functionalized surface. This method would urge us to specifically integrate functional monomers into prepared samples for developing functionalized surface with orthogonal multi-stimulus response (Fig. 1c). In addition, dipole-dipole interactions were typical dynamic interactions, which can facilitate the assembly and disassembly of polymer-network structures by employing heat and force as stimuli (Fig. 1c). Therefore, a thermo- and force-induced reversible 3D structural switching would be created using self-growing method to specifically integrate dipole-dipole interactions into 3D structure. Next, the thermally stable green fluorescence dye and photochromic dyes were incorporated into the pre-programmed 3D structure using a self-growing method. A typical photo-induced fluorescence resonance energy transfer (FRET) process occurred, resulting in the photo-induced reversible fluorescence switching between green and red (Fig. 1c). During growth-induced size expansion, mechanical tension was caused in the polymer networks, which hindered the structural growth. Transesterification-based chain exchange step was thus designed to eliminate such tension to ensure stable 3D structures (Fig. 2a). Finally, a photo-, thermo-, and force-induced dual-modal (2D/3D) switching systems were created (Fig. 1c). They were supposed to exhibit some favorable features, including excellent photo- and thermo-responsiveness and reversibility, high fluorescence contrast, and self-healing properties.

Time-and space-controlled growth of 3D structures
The starting coatings (seeds) were prepared via a copolymerization of trifluoromethyl-rich monomers (2,2,2-trifluoroethyl methacrylate (TFEMA, monomer) and 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA, comonomer) and hexamethylene diacrylate (HDDA, crosslinkers) in the presence of a photoinitiator (I819, Fig. 2a, b, c and Supplementary Fig. 1). The seed is named as P0 (Supplementary Table 1, nTFEMA/nHFBA = 1/1). Next, the nutrients made from trifluoromethyl-rich TFEMA and HFBA (nTFEMA/nHFBA = 2.5/1), and crosslinker (HDDA) were employed to swell seeds within 4 h (Fig. 2a, b, c and Supplementary Figs. 2, 3). To prevent sample damage caused by excessive swelling, we chose 1.5 h as the swelling time. The swollen samples were sealed and stored in the dark for 1 d to ensure that the nutrients were evenly distributed in seeds. The stable samples were exposed to blue light (460 nm, 10 mW/cm2) to grow 3D structure under a mask with a circular hole (d = 2 mm). As shown in Fig. 2d, the 3D structure gradually grown on the surface of seeds within 460 s, accompanying with a significant linear increase in the height of a circular pillar (h = 286 μm, Fig. 2d, e, f and Supplementary Fig. 4). Finally, anti-counterfeiting coating was successfully fabricated based on BSA-induced transesterification. BSA-induced transesterification can eliminate growth stress to ensure the stability of coating (Supplementary Fig. 5)50. In addition, atomic force microscopy (AFM) was used to capture microscopic variations in surface morphology (5 × 5 μm). The surface of the seed and grown 3D structure appears to be relatively smooth (Supplementary Fig. 6a, b). These results proved that the growth process of 3D structures is time-controllable.

Space-controlled growth of 3D structures was also investigated. Essential to this synthesis, 2-(6-(dimethylamino)−1,3-dioxo-1H-benzodeisoquinolin-2(3H)-yl)ethylacrylate (MNEA, green fluorescence dye, Supplementary Fig. 7) and 4-(acryloyloxy)butyl-4-(2-methyl-3-(2-(2-methylbenzothiophen-3-yl)−4-oxo-5,6-dihydro-4H-thieno-2,3-thiopyran-3-yl)benzothiophen-6-yl)−4-oxobutanoate (BTBA, photochromic dyes, Supplementary Fig. 8) were first synthesized based on our previous work28,53. MNEA exhibited a stable green fluorescence (Supplementary Fig. 9). BTBA revealed reversible fluorescence switching between none and red fluorescence (Supplementary Fig. 10). Subsequently, we fabricated the seeds containing MNEA or BTBA using one-pot photo-induced radical copolymerization. Seeds containing MNEA exhibited an absorption peak (375 nm, Supplementary Fig. 11a) and a green fluorescence emission peak (506 nm, Supplementary Fig. 11b). Seeds containing BTBA showed a reversible switching in absorbance and fluorescence emission under alternating UV and Vis. irradiation (Supplementary Fig. 11c, d). When we used the nutrients including TFEMA, HFBA, MNEA, BTBA, and HDDA to grow 3D structures (typical pillar shape, the grown coatings were named as P1-P12, Supplementary Table 1), grown structures (P1, nTFEMA/nHFBA = 2.5/1) exhibited the absorption peak of MNEA and the reversible absorption peak of BTBA under alternating UV and Vis. irradiation, whereas no absorption peak was observed in the non-growing areas (Fig. 3a, b, c). Especially, UV could induce a color change form pale yellow to pink in grown structures containing MNEA and BTBA (Fig. 3b). We also tested the fluorescent cross-section images of the grown structure made from 460 s. As shown in Fig. 3d, the growth area showed obvious green fluorescence, and the fluorescence intensity was highest at the top surfaces (Fig. 3e and Supplementary Fig. 12a, b). More complex 3D patterns could be constructed by employing complex masks (Fig. 3f). These results demonstrated that spatial-controlled growth was feasible. The time- and space-controlled growth would prompt us to create an advanced anti-counterfeiting and encryption system via on-demand coupling 2D and 3D information.

Coupling responsive 2D and 3D information
The above results demonstrated the effectiveness of the time- and space-controlled growth of this growth strategy. Based on this, the common monomers (i.e., 2-hydroxyethyl acrylate) were used to grow 3D structure (3D information, Fig. 4a). Growing 3D structure could return to its initial state after being pressed at 60 °C and then fixed at 25 °C, indicated that growing 3D information had no responsiveness to heat and force (Fig. 4a, b). When we utilized TFEMA and HFBA as functional monomers to construct 3D information (Fig. 4c), the 3D structure exhibited a typical thermally induced shape memory. When we compressed it at high temperature (T = 60 °C) and placed it in a low temperature environment (T = 25 °C), its 3D structure almost disappeared (h = 30 μm, Fig. 4c, d), and then continued to maintain this state at temperature below 40 °C. Subsequently, the 3D structure was recovered in a relatively high-temperature environment (T = 45 °C). This process was reversible (Fig. 4d). This feature should be attributed to be fact that growing 3D structure have a shape-memory transition temperature (Ttrans = 40 °C). Ttrans depended on the glass transition temperature (Tg). Briefly, when a high temperature of 60 °C was used, dipole-dipole interaction showed an excellent dynamic characteristic, and growing 3D structure was elastic (T > Tg = 40 °C). The compressive stress can be released by dynamic interaction, resulting in the disappearing 3D structure and metastable covalent crosslinking points (Fig. 4c). When the temperature is below Ttrans (T = 25 °C, T < Tg), dipole-dipole interaction exhibited a weak dynamic performance, P1 acted as typical thermoset, which would promote a metastable 3D structure to remain in its current state rather than recover. Subsequently, upon the enhancement of T (T = 45 °C), the metastable covalent crosslinking points would drive 3D structure recovery. Finally, the 3D structure reverted to its original state. Thus 3D structural cycling could be achieved based on thermo- and force-induced shape memory properties caused by dipole-dipole interaction and covalent bond. In addition, we used atomic force microscopy (AFM) to acquire microscopic variations in surface morphology after the stimulation of force (5 × 5 μm). A relatively smooth surface of grown 3D structure was presented (Supplementary Fig. 6b). When 3D structure disappears by the force stimulus, only tiny structures on its surface are observed (Supplementary Fig. 6c). Transmission electron microscopy (TEM) was also employed to observe the non-growing area (grown 3D structure) and the growing area of the growing sample. The results indicated that growth did not induce nano-scale microstructures (Supplementary Fig. 13).

Furthermore, we further explored the shape-memory property. The sample could be returned to its initial state from various shapes (twist and bend shapes, Supplementary Fig. 14), and even various embossed patterns can be erased at 45 °C (Supplementary Fig. 15). Our previous works revealed that Tg of the polymer made from TFEMA and HFBA gradually increased as the enhancement of TFEMA fraction54. Therefore, we tried to adjust Ttrans by tuning Tg, which can induce a programmed control of thermo-response 3D information. The different samples (P1 (nTFEMA/nHFBA = 2.5/1), P5 (nTFEMA/nHFBA = 1/1), P6 (nTFEMA/nHFBA = 0.5/1), P7 (nTFEMA/nHFBA = 1.5/1), P8 (nTFEMA/nHFBA = 2/1)) were prepared to explore their Tg and mechanical properties (maximum tensile strain (ε), modulus (E), strength (σ), toughness (T)). The more proportion of TFEMA caused coating to show a higher Tg (Supplementary Fig. 16) and a better mechanical property including high E and σ (Supplementary Fig. 17 and Supplementary Table 2).

Next, the green fluorescence dyes (MNEA) and photochromic molecules (BTBA) were integrated into growing 3D structures (Fig. 4e). The introduction of MNEA and BTBA does not affect the mechanical properties of the 3D structure due to the quite low content of fluorescence dyes and photochromic molecules (MNEA (0.025 ‰mol), BTBA (1.5 ‰mol), Supplementary Fig. 18). The growing 3D structures containing MNEA and BTBA revealed a fluorescence change from green to red (Fig. 4e). The large spectral overlap between the fluorescence emission of MNEA and the absorption of the closed-ring structure of BTBA (BTBA-c) demonstrated that an efficient FRET process could occur (Supplementary Fig. 19). Therefore, we further optimized the FRET efficiency of coating containing the different ratio of MNEA to BTBA (P1 (nTFEMA/nHFBA = 2.5/1, nMNEA/nBTBA = 1/60), P2 (nMNEA/nBTBA = 1/15), P3 (nMNEA/nBTBA = 1/30), P4 (nMNEA/nBTBA = 1/50), P5 (nTFEMA/nHFBA = 1/1, nMNEA/nBTBA = 1/60), Supplementary Fig. 20). When the ratio of MNEA to BTBA was 1/60 (P1 (nTFEMA/nHFBA = 2.5/1)), the FRET efficiency was up to 90.7% (Fig. 4f and Supplementary Fig. 21). When they were exposed to UV, the color and fluorescence were changed yellow to red, green to red, respectively (Supplementary Figs. 20 and 21). Their color and fluorescence could be reversibly switched between under the irradiation of ultraviolet (UV, 365 nm, 2.8 mW/cm2) and visible light (Vis., 525 nm, 1.34 mW/cm2). Therefore, we chose P1 as the typical sample to perform subsequent optical tests. An effective photo-induced FRET process between the MNEA and BTBA were demonstrated based on a decreased fluorescence lifetime (9.67 ns to 2.76 ns, Supplementary Fig. 22). These results demonstrated that a photo-induced FRET process between the MNEA and BTBA was successfully created in the reprogrammable growing 3D structures. In addition, the thermostability of BTBA was evaluated before and after UV irradiation. When P1 were placed in a dark thermal environment (80 °C), its fluorescence intensity at 500 nm and 650 nm only presented a slight change within 24 h, indicated the excellent thermostability of BTBA-c (Supplementary Fig. 23).

Photo- and thermo-induced switching properties
The photoswitchable fluorescence property of P1 was investigated. As shown in Fig. 5a, upon the irradiation of UV (365 nm, 2.8 mW/cm2), the fluorescence intensity (500 nm) of MNEA decreased significantly within 10 min, whereas the fluorescence intensity (650 nm) of BTBA exhibited an opposite trend. This process was accompanied by a change in fluorescence from green to red (Fig. 5b). When the sample was exposed to Vis. (525 nm, 1.34 mW/cm2), the red fluorescence disappeared, and the green fluorescence returned within 12 min. In addition, when we alternately stimulate P1 with UV and Vis., no significant photobleaching were observed even more than 20 cycles, demonstrating an excellent reversibility (Fig. 5c). Based on this, we further explored the thermo-responsiveness of the 3D structure. First, we erased the 3D structure of P1 using pressing at 60 °C and fixing at 25 °C. Then, the disappeared 3D structure still maintained at 25 °C and 35 °C, whereas it can recover quickly when T was above Ttrans (Fig. 5d, e). Similarly, P1 can withstand 20 cycles without significant change under different stimuli (Fig. 5f). These results demonstrated that P1 have excellent responsiveness (fast response rates) and reversibility.

Growth-induced healing property
Self-healing ability is a desirable property for elongating the service time of materials55,56. We explored a growth-induced healing strategy57,58. As shown in Fig. 6a, the surfaces of all parts (Seed, P0 (nTFEMA/nHFBA = 1/1)) adhered after the application of the nutrient solution (nTFEMA/nHFBA = 1/1) because of the dipole-dipole interaction. Subsequently, in situ polymerization produced new polymer chains and formed a strong entanglement to lock the interface, resulting in a high self-healing efficiency of 72.6% (P0-1, Fig. 6b). When we used the nutrients containing more TFEMA fraction (nTFEMA/nHFBA = 2.5/1) to perform, a higher self-healing efficiency of 94.2% were obtained (P0-2, Fig. 6b). The healed sample can support 100 times its own weight (200 g, Supplementary Fig. 24). To demonstrate the advantages of growth-induced healing, we designed and fabricated a complex cup (Fig. 4c and Supplementary Fig. 25). The artificial cup was constructed by self-healing driven by dipole-dipole interaction, and then the contact points are strengthened by growth self-healing. As shown in Fig. 6c, the artificial cup can hold 9.35 g of quartz sand and 8.0 g of water without deformation. The photoswitchable fluorescence in special parts (label and handle) was observed, demonstrating that growth-induced self-healing does not affect the fluorescence property of the bonded region. This self-healing method was desired for applying it in the practical anti-counterfeiting fields.

2D/3D-encoding multistage information encryption and anti-counterfeiting
The integration of responsive fluorescence (2D) and 3D information encoding in one system could significantly enhance information security. To demonstrate this, we prepared 3D structures with varying fluorescence information and Tg (Fig. 7a). In the original state, green fluorescence information (“7”) and 3D information (“3”) were displayed and as a result, the coupled information “73” was achieved (Fig. 7a). When we pressed at 60 °C to eliminate part of the 3D information, and then fixed at 25 °C, green fluorescence information (“7”), 3D information (“1”), and coupled information (“71”) were observed. When it was exposed UV for 600 s, the new red fluorescence information (“3”) emerged, the coupled information was “31”. When the temperature increase to 30 °C and 45 °C, the red fluorescence remained unchanged, 3D information transformed to “7” and “3”, which could induced a change in coupled information (“37” and “33”). Finally, by employing Vis. (525 nm, 1.34 mW/cm2) to irradiate it, all information was returned to the original state (Fig. 7a). In addition, we grew the thirteen pillars on the matrixes to present number “8” and perform the anti-counterfeiting demonstration (Supplementary Fig. 26). We first eliminated the 3D information as an original state. Only green fluorescence (“5”) could be seen. Temperature (T = 30 °C and T = 45 °C) induced 3D information “5” and “8” to be displayed, accompanying with coupled information “55” and “58”. UV could further cause the coupled information of “88”. Finally, a press operation and their radiation of visible light could restore system to its initial state.

In practical applications, anti-counterfeiting labels are crucial for identifying counterfeits and substandard products. We tried to apply the responsive coating to create 2D/3D dual-mode anti-counterfeiting labels. As depicted in Fig. 7b, we regulated the proportion of fluorescent dyes and fluorinated monomers through twice growth, enabling the cloud and raindrops to contain different fluorescence pattern and Tg values (cloudy: P8 (nTFEMA/nHFBA = 2.0/1, nMNEA/nBTBA = 1/60), rain: P10 (nTFEMA/nHFBA = 2.5/1, nMNEA/nBTBA = 1/0)). By using force and heat as stimulus, the 3D pattern disappeared, and only a green pattern (rain) was observed. Subsequently, the different Tg (30 °C and 45 °C) would induce the 3D or coupled pattern of “cloudy” and “rain”. UV and press further facilitate the transformation of coupled pattern into “rain” with red fluorescence and “no pattern”. Finally, Vis. irradiation drove the coupled pattern to its original state. Inspired by the unfolding of lotus petals in response to temperature, we designed a flower that could open layer-by-layer in response to temperature. Every layer of the flower contained different fluorescence information by using a variety of masks and precisely adjusting the proportion of fluorinated monomers. Three layers were prepared using one-pot photo-induced radical copolymerization of two monomers, and then grow the 3D structure using some nutrients containing different dyes (bottom: MNEA (P11 (nTFEMA/nHFBA = 1.5/1, nMNEA/nBTBA = 1/60)), middle: BTBA (P12 (nTFEMA/nHFBA = 2/1, nMNEA/nBTBA = 0/60)), top: MNEA and BTBA (P1 (nTFEMA/nHFBA = 2.5/1, nMNEA/nBTBA = 1/60)), Supplementary Fig. 27). As shown in Fig. 7c and Supplementary Movie 1, in the initial state, flower was not open and did not display any information. With a gradual increase in temperature (T = 20 °C, T = 30 °C, and T = 45 °C), the petals slowly opened, and the 3D structures gradually were shown. Under UV irradiation, the green fluorescence information “HUNAN” was unchanged, and the green fluorescence of the six-point star pattern was turned into red emission. New information “HNUST” then emerged. These results showed that the responsive coating could promote the high security of anti-counterfeiting via skillfully combining 2D information and 3D information.

Methods
Materials
2,2,2-trifluoroethyl methacrylate (TFEMA, 96%), 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA, 96%), hexamethylene diacrylate (HDDA, 90%), 2-hydroxyethyl acrylate (HEA, 98%) phenylbis(2, 4, 6-trimethylbenzoyl)phosphine oxide (I819, 99%), and benzenesulfonic acid (BSA, 90%) were bought from HEOWNS. TFEMA, HDDA, HFBA, and HEA were purified by column chromatography to remove the polymerization inhibitor before use.

Preparation of seeds (P0)
A mixture solution of HDDA (cross-linker, 13.8 mg, 0.1 mmol), I-819 (photoinitiator, 85 mg, 0.2 mmol), TFEMA (1.68 g, 10 mmol), HFBA (2.36 g, 10 mmol) were placed in 1 h in reaction cells consisting of a pair of glass plates with 1.0 mm spacing, and then irradiated using Vis. (460 nm, 10 mW/cm2) for 1 h. Next, the polymer blocks were immersed into a large amount of a mixture of petroleum ether and ethanol to remove residual monomers and dried at 80 °C for 6 h to obtained seeds.

Preparation of grown samples (P1)
Taking P1 as a typical sample. The seeds were immersed into the nutrients containing HDDA (13.8 mg, 0.1 mmol), I-819 (85 mg, 0.2 mmol), TFEMA (2.40 g, 14.3 mmol), HFBA (1.35 g, 5.7 mmol), MNEA (0.15 mg, 0.0005 mmol), BTBA (20 mg, 0.03 mmol) for 1.5 h. The 3D structure (cylinder) was grown in a box using a mask. Subsequently, the growing samples were dialyzed into a mixture of petroleum ether and ethanol (three times), and then dried at 80 °C for 6 h. Next, the obtained samples were soaked into an ethanol solution containing benzenesulfonic acid (BSA, 1 wt%) and dried 25 °C for 24 h. The dried samples were heated at 80 °C for 8 h to trigger chain exchange for eliminating grown stress and then dialyzed in ethanol to remove BSA. Finally, P1 was fabricated by drying at 50 °C for 12 h. The other grown samples (P1, P2, P3, P4, P6, P7, P8, P9, P10, P11, P12) were prepared via the same process using different TFEMA and HFBA, and MNEA and BTBA. The corresponding compositions are listed in Supplementary Table 1. For growing 3D structures, the masks were selected according to demand (pillar, flower, number, pattern).

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The authors propose a novel concept of self-growth of programmable 2D/3D-coupling responsive coating for multi-dimensional anti-counterfeiting and encryption by combining photoswitchable fluorescence and supramolecular interaction (dipole-dipole interaction). They used self-growing method to introduce photoswitchable fluorescence and supramolecular interaction into specific 3D structure. Interestingly, coupled 2D/3D information can be switched reversibly and independently. The authors also demonstrated that programmable 2D/3D-coupling responsive coatings can be applied to create multistage anti-counterfeiting label, and enhancing the security of encryption and anti-counterfeiting. Overall, the manuscript is well-organized and there are exciting conceptual advances here that would be worth reviewing in Nature Communication. I am supportive of publication of this article after minor revision as listed below.\n1. The authors should provide the chemical structure of monomers (TFEMA, HFBA, HEA, and HDDA) to improve readability.\n2. The authors only exhibited the stress-strain curves of P1, P5, P6, P7, and P8. They should provide detailed data (i.e., maximum tensile strain (ε), modulus (E), strength (σ), toughness (T)).\n3. I suggested that the author should investigate the influence of fluorescence dyes and photochromic molecules on the mechanical properties of coatings.\n4. Growth strategy is interesting for coupling the different anti-counterfeiting and encryption technologies. The authors are encouraged to discuss some existing potential of this method in more detail.", "reviewer_2": "Anti-counterfeiting encryption remains a crucial research area. Current 2D and 3D anti-counterfeiting technologies exhibit limited functionality and are prone to forgery. The novelty of this work lies in the integration of different 2D and 3D anti-counterfeiting methods, enabling independent control and reversible switching of 2D and 3D information Moreover, the anti-counterfeiting structure demonstrates self-healing capabilities. The work support the conclusion and claims. The methodology is sound. I only have some small questions:\n1.In the \"Anti-counterfeiting Coating Design and Preparation\" section, only \"Design\" is mentioned without \"Preparation\", which seems logically inconsistent as the latter is placed in a subsequent paragraph.\n2.The design component requires more detailed explanation, particularly regarding self-growth technology. For example, many readers are unfamiliar with self-growing. What kind of role that dipole-dipole interactions plays.\n3.It looks that self-growth as an irreversible one-time process. Is the aim of using self-growing to simply achieve specific shapes? If so, wouldn't it be more efficient to directly create three-dimensional patterns through imprinting methods instead of employing self-growth?", "reviewer_3": "This paper presents a method for constructing programmable 2D/3D coupled-response coatings using a self-growth strategy, designed for advanced anti-counterfeiting and information encryption. The work demonstrates outstanding novelty and an ingenious conceptual design, enabling independent and reversible manipulation of fluorescence (2D) and morphology (3D) information through orthogonal stimuli (light, heat, force), thereby achieving multidimensional encryption within a single system. The experimental data are comprehensive, the arguments are generally clear, and the demonstrated application examples are impressive, showcasing significant potential for practical implementation. Overall, this represents high-quality research of considerable value. The manuscript is recommended for acceptance after major revisions.\nQuestion 1:\nTable S1 in this paper lists the different sample compositions but does not provide a brief analysis of the key performance differences. It is recommended that the authors outline trends in how the different compositions affect sample performance to make better use of the data.\nQuestion 2:\nIn this paper, the FRET process between MNEA and BTB was primarily verified based on spectral overlap. It is recommended to supplement this analysis with dynamic light scattering (DLS) measurements to determine the microsphere size of the polymeric materials. Additionally, transmission electron microscopy (TEM) can be employed to observe the dispersion state and analyze the spatial distribution.\nQuestion 3:\nSome sentences in the article are ambiguous, and minor corrections are recommended. For example, the word “independently” in the sentence “Interestingly, coupled 2D/3D information can be switched reversibly and independently.” is unclear. It is suggested to clarify that when the 2D information is stimulated, the 3D information remains unchanged.\nQuestion 4:\nWhen characterizing the 3D structure, the author relies solely on macroscopic variation analysis. It is recommended to use atomic force microscopy (AFM) to capture microscopic variations in surface morphology, thereby enhancing the credibility of the data.\nQuestion 5:\nThe author may briefly explore the potential applications of this “self-growing” strategy in other fields, such as soft robotics and bioelectronic interfaces, to enhance the impact of the work.\nQuestion 6:\nIt is recommended that the authors incorporate additional scholarly references on message encryption in the introduction to strengthen the research context and provide a more comprehensive foundation for the study.\nAdvanced Materials, 2023, 35, 2306003, DOI: 10.1002/adma.202306003.\nAdvanced Optical Materials, 2024, 12, 2302146, DOI: 10.1002/adom.202302146."}, "author_response": "Manuscript number: NCOMMS-25-53297\nAuthors’ response to reviewers’ comments\nWe are grateful to all three reviewers for their insightful feedback and important suggestions. We are convinced that the detailed revisions, additional experiments, and clarifications, which we introduced following the comments of the reviewers, will strengthen our manuscript for publication.\nFor clarity, we show the reviewer’s comments in black, our responses in blue.\nReviewer #1:\n[... full author response text provided in the prompt ...]"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have made satisfied revision accordingly. The current version can be publishable as is.", "reviewer_2": "I have no further questions."}, "author_response": ""}]

Decision letter