Epoxy Resin Patterns Prepared Based on the Photochromism of a Cholesteric Liquid Crystal Mixture

Cholesteric liquid crystal polymer network (CLCN) patterns based on polyacrylate have attracted much attention for the applications in decoration and anti-counterfeiting. Although epoxy resin-based CLCN patterns can be prepared using thermochromic cholesteric liquid crystals (CLCs), it is hard to prepare them on a large scale on coating lines. Herein, a photochromic CLC mixture was prepared using a reactive epoxy liquid crystal and a photoisomerizable chiral dopant. Driven by the photoisomerization of the chiral dopant, the selective Bragg reflection band of the CLC mixture redshifted with increasing the 365-nm UV light irradiation time. Due to the high viscosity of the CLC mixture, the reflection band of the irradiated CLC mixture was both time- and temperature-dependent. After photopolymerization, the structural color was fixed. By precisely controlling the annealing time after the photoisomerization of the chiral dopant or the irradiation time for photoisomerization, colorful epoxy resin patterns were prepared, which have potential applications in decoration and anti-counterfeiting.