Preparation of chiral liquid crystal polymers with reversible structural colors and fluorescence emission and the application for dynamic anti-counterfeiting

Chiral nematic liquid crystal polymers, which exhibit reversible dynamic structural colours and fluorescence emissions in response to external stimuli, are highly secure and reliable materials for optical anti-counterfeiting. In this article, the chiral nematic liquid crystal polymers were synthesised through graft copolymerisation using polymethylhydrosiloxane (PMHS) as the main chain, chiral liquid crystal monomer M1, nematic liquid crystal monomer M2, and organic fluorescent anthracene compound M3 as side chains. The chiral nematic liquid crystal polymer (CLCP7)possesses a chiral helical structure that allows for selective reflection based on temperature changes, resulting in dynamic and reversible colour variations. Additionally, the discrete anthryl chromophoric segments within the CLCP7 matrix facilitate tunable photoluminescence which can be adjusted by manipulating the temperature. Furthermore, the CLCP7 exhibits highly sensitive photoluminescence response. The dynamic and reversible characteristics of structural colour and fluorescence emission make the CLCP7 an ideal candidate for intelligent optical anti-counterfeiting materials development with potential applications spanning information security and anti-counterfeiting domains.