Time‐Dependent Information Encryption in Liquid Crystalline Polymer with Programmable Glass Transition Temperature

Abstract Time‐dependent dynamic information encryption technology is a promising approach to enhancing the security and complexity of information transmission. Herein, a time‐dependent information encryption model from a liquid crystalline polymer (LCP) film with a programmable glass transition temperature (T_g) and gradually adjustable fluorescence is demonstrated. The programmable T_g is achieved by adjusting the degree of order of the LC molecules via a configuration interconversion of spiropyran‐based materials (SPBMs), which can convert between a V‐shaped colorless spiro (SP) and a rodlike dark‐colored merocyanine (MC) form. An LCP film obtained by visible light polymerization exhibits a lower T_g than UV light, because the SPBM molecules keep different configurations in the two films. By adjusting the ratio of two isomerization forms of SPBM molecules during the polymerization process, the T_g values of LCP films can change from 11.6 °C to 31.1 °C. Based on the isomerization rate of SPBM in the LCP films with different T_g, time‐dependent information encryption is successfully achieved.