Versatile and robust transparent polymer film with preprogrammed diffusion and bidirectional irreversible fluorescence for sequential information encryption.

The materials currently available for information encryption often suffer from low transparency, poor mechanical strength, and a reliance on single decryption conditions, which limits their security and hence application potential. To address these challenges, we developed a transparent, mechanically robust polymer film inspired by the camouflage and communication strategies of the glass squid. In this film, 2,5-dihydroxyterephthalic acid (DHTA) and zinc acetate dihydrate are integrated into a crosslinked polyvinyl alcohol-glutaraldehyde (PVA-GA) matrix to achieve bidirectional irreversible fluorescence and sequential decryption. The material exhibits high transparency (>89 %) and impressive tensile strength (60 MPa), and its fluorescence responses can be tuned with UV light, alkaline conditions, and high-temperature ethanol solutions. Based on preprogrammed diffusion rates, customizable time-based decryption can be achieved with the film, advancing multilevel encryption techniques. These findings demonstrate that this film represents a promising platform for secure information encryption and anticounterfeiting applications.