A cholesteric liquid crystal elastomer film with dual helical pitches formed by molecular diffusion

Abstract

Cholesteric liquid crystal elastomer (CLCE) films with single helical pitch have been applied in decoration and anti-counterfeiting. Herein, CLCE films with dual helical pitches were prepared by coating and polymerization of a cholesteric liquid crystal oligomer on the surface of a CLCE film. Due to the penetration of the liquid crystal oligomer, the helical pitch of the bottom CLCE film increased. It was found that the penetration rate of the oligomer solution was high and the organization of the oligomer molecules was time-consuming. A CLCE/thermoplastic polyurethane (TPU) film with dual reflection bands was prepared by transfer printing the CLCE film from the polyethylene terephthalate film. The reflection bands of the CLCE/TPU film blueshifted with increasing uniaxial stretching strain. Two CLCE/TPU patterns with a composite colour were prepared through screen printing, which could be applied for decoration and anti-counterfeiting.