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

Abstract

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 (<n>) 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...

Magnetic response of photonic crystals based on nucleating agents of binuclear complexes

“…Monodispersed superparamagnetic nano Fe 3 O 4 is particularly suitable for constructing MRPCs due to its superior responsiveness compared to conventional paramagnetic materials. Moreover, the interactions between dipoles of Fe 3 O 4 nanoparticles could be effectively controlled by an EMF, 3 which makes them highly promising for several applications, such as sensor-type PCs for responding to temperatures and mechanical forces, [4][5][6][7][8] color display-type PCs for anti-counterfeiting and printing, [9][10][11][12] and grating-type PCs for optical adjustment, 13,14 etc.…”

Hybrid Encoding Strategy of Multi-Stimulus Response Aggregation-Induced Emission Hydrogels for Advanced Information Encryption and Safety

“…In this aspect, stimuli-responsive fluorescent hydrogels with controllable optical properties (absorption, emission intensity and wavelength, luminescence lifetime, etc.) under external stimuli (such as light, electricity, force, heat, and ions) − show great potential for applications in information storage − and security anticounterfeiting. , Li and researchers prepared a rapid and reversible thermochromic fluorescent supramolecular polymer hydrogel . The incorporation of TPE units into the supramolecular hydrogel imparts it with bright blue fluorescence, which meets the requirements for protection and quick response codes with enhanced safety.…”

Ultrasensitive Biomimetic Skin with Multimodal and Photoelectric Dual-Signal Sensing

“…24 λ 0 of PSCLC film prepared by a combination of alternating electric field and Michael addition reaction (MAR) undergoes a redshift as temperature increases. 25 Extensive efforts have already been dedicated to the development of a PSCLC film with sensing functionality. Recently, on a polymerized ionic liquid network, a multifunctional PSCLC film was synthesized through in situ free-radical photopolymerization of Michael addition and PSCLC precursors, enabling both tension and pressure sensing.…”

“…Leveraging the large elastic anisotropy and Poisson’s ratio (>0.5) of PSCLC film, a chromatic shift spanning from near-infrared to ultraviolet wavelengths can be achieved during pneumatic inflating . λ 0 of PSCLC film prepared by a combination of alternating electric field and Michael addition reaction (MAR) undergoes a redshift as temperature increases . Extensive efforts have already been dedicated to the development of a PSCLC film with sensing functionality.…”