Patterned cholesteric liquid crystal polymer network film with precisely controlled structural colors prepared using a handedness invertible photochromic cholesteric liquid crystal mixture

Cholesteric liquid crystal polymer network (CLCN) patterns composed of oppositely handed helical structures are attractive for anti-counterfeiting. Different areas can be observed under the circularly polarized light with opposite handedness. However, achieving precise control over the reflection band wavelengths of CLCN patterns using photochromic cholesteric liquid crystals (CLCs) remains a significant challenge. Herein, we synthesized a chiral cyanostilbene derivative that demonstrated significant modulation of its helical twisting power upon 365 nm ultraviolet (UV) irradiation. When incorporated into CLC mixtures, this additive enabled precise control over both the handedness and reflection wavelength of the resulting CLCN patterns within seconds under UV exposure. The system allowed for the preparation of colorful CLCN patterns through in-situ photopolymerization. These findings demonstrate that the developed CLC mixtures are well-suited for high-throughput fabrication of CLCN patterns on industrial coating lines.