Fluorescent nematic liquid crystalline oligomers with reversible texture and photoluminescence response to temperature

Abstract

Fluorescent liquid crystals in luminescent materials have attracted considerable interest owing to their unique feature of fluorescence in response to external stimuli and their applicability in information security and anti-counterfeiting. Herein, fluorescent nematic liquid crystalline oligomers (FNLCO) containing pyrene chromogenic segments with tunable fluorescence properties and dynamic reversible striped textures were dexterously designed and prepared by poly(methylhydrogeno)siloxane (PMHS), liquid crystalline monomer M₁, monomer M₂, and fluorescent pyrene compound M₃. The discrete pyrene chromophore in the FNLCO matrix can enable tunable photoluminescence. Therefore, FNLCO can emit blue fluorescence by irradiating with ultraviolet light, and the fluorescence intensity can be reversibly and precisely controlled by applying thermal stimuli. The as-prepared FNLCO display reversible striped textures during the heating and cooling process, and surprisingly, the striped textures and fluorescence can be simultaneously and precisely adjusted by temperature. Temperature-driven dynamic fluorescence patterns with FNLCO can be made with fast and reversible response. The reversible thermal driven dynamic reversible striped textures and fluorescence properties can make smart materials promising candidates in the field of high-level anti-counterfeiting.