Multicolor photonic patterns through an intensity-controlled single photopolymerization step

Foelen, Yari; Gils, Nieke van; Claessen, Mart; Schenning, Albert P. H. J.

doi:10.1039/d2cc04050f

Cited by 3 publications

(2 citation statements)

References 25 publications

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“…When compared to the first example, the initial color of the 6 mJ/cm 2 region might be due to batch-to-batch difference, leading to small changes in the concentration of the chiral dopant in the ink. The blue-shifted color at 3 mJ/cm 2 UV dose might be due to the changes in the helical twisting power of the chiral dopant during the slow polymerization kinetics. , Moreover, as the bicolored label was stretched, the reflection spectra blue-shifted nonuniformly, and the color-separation effect was enhanced. The color-separating effect can again be attributed to the nonuniform thickness change between the 6 and 3 mJ/cm 2 regions.…”

Section: Results and Discussionmentioning

confidence: 99%

Sticky Multicolor Mechanochromic Labels

de Castro,

Engels,

Oliveira

et al. 2024

ACS Appl. Mater. Interfaces

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Sticky-colored labels are an efficient way to communicate visual information. However, most labels are static.Here, we propose a new category of dynamic sticky labels that change structural colors when stretched. The sticky mechanochromic labels can be pasted on flexible surfaces such as fabric and rubber or even on brittle materials. To enhance their applicability, we demonstrate a simple method for imprinting structural color patterns that are either always visible or reversibly revealed or concealed upon mechanical deformation. The mechanochromic patterns are imprinted with a photomask during the ultraviolet (UV) cross-linking of acrylate-terminated cholesteric liquid crystal oligomers in a single step at room temperature. The photomask locally controls the cross-linking degree and volumetric response of the cholesteric liquid crystal elastomers (CLCEs). A nonuniform thickness change induced by the Poisson's ratio contrast between the pattern and the surrounding background might lead to a colorseparation effect. Our sticky multicolor mechanochromic labels may be utilized in stress−strain sensing, building environments, smart clothing, security labels, and decoration.

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Section: Results and Discussionmentioning

confidence: 99%

Sticky Multicolor Mechanochromic Labels

de Castro,

Engels,

Oliveira

et al. 2024

ACS Appl. Mater. Interfaces

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“…[24][25][26] To solve that problem, photoisomerizable materials like azobenzene were added to realize the "light" programming of nanostructure by changing light exposure conditions. [28][29][30][31] In addition, based on the irreversible mechanical response, imprinting technology was also used to program the refractive index of the nanostructure. [32,33] In pursuit of higher-level encryption, steganography, realized by writing patterns and information in the stimulated state through programming response characteristics, is widely used in multicolor anticounterfeiting.…”

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confidence: 99%

Hybrid Encoding Strategy of Nanostructures for High‐Performance Security Information Encryption

Zhu

et al. 2023

Advanced Optical Materials

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specific external stimuli [14][15][16][17] can be used to carry and transmit unique information, so that SPCs have wide potential applications in fields of displays, lasing, and information security. [18][19][20] Cholesteric liquid crystal polymers/ films (CLCPs/CLCFs) are self-assembled 1D SPCs. [21][22][23] Bright structural color is produced by their unique helical nanostructures. The Bragg center wavelength (λ B ) of CLCPs/CLCFs depends on the pitch (p) of their helical nanostructure and the average refractive index of liquid crystal mixture () determines the Bragg center wavelength (λ B ) of CLCPs/CLCFs. The encrypted information can be written by programming colors with different strategies and recoded by ultraviolet (UV) irradiation. The p of CLCPs/CLCFs consisting of reactive small molecule mono mer or oligomer can be easily changed by external stimuli, including temperature [24,25] and electric field. [26,27] However, the change of λ B is usually retained by the polymerization of acrylate monomers. [24][25][26] To solve that problem, photoisomerizable materials like azobenzene were added to realize the "light" programming of nanostructure by changing light exposure conditions. [28][29][30][31] In addition, based on the irreversible mechanical response, imprinting technology was also used to program the refractive index of the nanostructure. [32,33] In pursuit of higher-level encryption, steganography, realized by writing patterns and information in the stimulated state through programming response characteristics, is widely used in multicolor anticounterfeiting. For example, the polymer containing hydrogen bonds was treated with the alkaline K + /Ca 2+ solution to obtain a humidity response, which could be programmed by the solution concentration. [34][35] It is a more common strategy to program the different response characteristics of polymers through different exposure conditions (time [36] and intensity [25,37] ). The nanostructure and mechanical response characteristics of CLCPs were programmed by the Michael addition reaction (MAR) time. [38] Combined with mask exposure technology, high-encrypted structural color pattern steganography was achieved. The single programming of nanostructure and response characteristics (structural color in the stimulated state) was discussed in detail in these works. Recently, our group presented a complex biomimetic structure with programmable synergistic shape transformations and nanostructure changes Programing nanostructure of soft photonic crystal materials to try to diversify has great potential for application in the field of information security, lasing, and display. However, complex programming nanostructures for regulating and controlling their structural color and stimuli-response behavior remain a technical challenge. Here, a strategy is demonstrated for hybrid encoding nanostructures of soft photonic crystals using cholesteric liquid crystal films (CLCFs). The public and secure information can be easily edited through the independent tuning of Bragg ce...

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