Time‐Dependent Wrinkle Pattern Based on Photo‐Controlled Stress Relaxation for Multi‐Level Information Encryption and Information Camouflage

Abstract

Stimuli‐responsive surfaces have garnered intensive research attention in addressing the challenges of severe information leakage problems, but they exhibit limitations in terms of intricate preparation and compatibility. Herein, the study reports a time‐dependent wrinkled surface controlled by photo‐induced stress relaxation of azobenzene‐ containing crosslinked polymer network comprised of furan‐containing polymer (PEA‐Fu) and maleimide‐substituted azobenzene (AZO‐2MI) as skin layer. Two kinds of wrinkled surfaces induced by two crosslinked networks (thermal‐ and UV‐induced) can be prepared by Diels‐Alder reaction and UV‐induced radical coupling reaction, exhibiting distinct amplitude decrease rate resulted from different stress relaxation rate induced by photo‐isomerization of azobenzene. By UV preprogramming with photomasks, various time‐dependent wrinkle patterns are obtained and can be identified at specific times under 450 nm irradiation. The time window for information read out can be preset through different UV preprogramming time and boundary conditions to achieve multi‐level information encryption. Furthermore, the written information can be camouflaged as another “false” information by regional‐selective irradiation under 450 nm irradiation, which offers a new method for information protection. Based on distinctive time‐dependent characteristics and excellent stability, this responsive wrinkled surface offers bright prospects in multi‐level information encryption.