Chiral liquid crystalline networks demonstrating reversible optical texture and reversible fluorescence towards dynamic anti-counterfeiting

Abstract

A dynamic surface pattern with tunable liquid crystalline texture and fluorescence in response to external stimulus can enable information recording and reading. Therefore, such patterns are widely used in the field of information security and anti-counterfeiting. A higher level of security in anti-counterfeiting is extremely desirable but challenging, herein, the chiral liquid crystalline networks (CLCN) used for anti-counterfeiting displaying both dynamic reversible Grandjean textures and fluorescence were dexterously designed and prepared by graft copolymerization of polymethylhydrosiloxane (PMHS), nematic liquid crystal M1, chiral crosslinker M2 and organic fluorescent pyrene compounds M3. The CLCN can emit blue-fluorescence when irradiating with ultraviolet light. More importantly, the Grandjean textures and fluorescence can be simultaneously and precisely adjusted by temperature. The as-prepared CLCN display reversible Grandjean textures during the heating and cooling process from the intrinsic chiral arrangement of CLCN. The discrete pyrene chromogenic segments in CLCN matrix enable the tunable photoluminescence by temperature, furthermore, the CLCN present highly sensitive photoluminescence evolution. The dynamic reversible Grandjean textures and fluorescence make the smart materials promising candidates in anticounterfeiting, providing a versatile strategy to fabricate intelligent optical anti-counterfeiting materials.