Single-actuated and fully recyclable phase change materials enabled multiple thermochromism toward information storage and encryption

The stimulus-responsive chromic materials under the single-triggered condition are hard to deal with the advanced forgery or tampering technologies due to its simple color variation. Herein, a novel multiple thermochromism materials (G-LPCMs) was synthesizing through structuring a gel factor as skeleton to adsorb intrinsic thermochromic component (TC) and thermochromic microspheres (TCM) in a simple way. The cooperation of TC and TCM can endow the G-LPCMs with rich color variations from blue to white and ultimately to pink at different temperature ranges, realizing multiple color variations in one material. Capitalizing on this rich color variation characteristic, a digital encryption system can be designed only by using its color change under single thermal-triggered condition. The devised cryptographic system can reversibly achieve the functions of information storage, information erasure and information reorganization during the cyclic heating–cooling process. Moreover, the synthetic G-LPCMs can be recycled only by simple heating, those chemical structure, crystal structure, and information encryption function can basically remain unchanged after multiple thermal cycles, greatly enhancing their service life for the security system. This work offers a new design for thermochromic PCMs that have the rich color variation characteristic in one material under single stimulus.