Anisotropic Molecular Diffusion Induced by Photogradient Polymerization of Chiral Nematic Liquid Crystal Monomers and the Formation of Helical Pitch Gradation

Abstract

Chiral-nematic liquid crystals (N* LCs) exhibit a refractive index distribution along their helical axis. Due to their helical structure, N* LCs reflect light at wavelengths corresponding to their helical pitch. Since the helical pitch is dependent on the concentration of chiral molecules, altering this concentration can induce various reflection colors. This study aimed to create reflection color gradation in N* LC films through photogradient polymerization. A mixture of LC monomers and non-polymerizable chiral molecules was subjected to photogradient polymerization. We analyzed the reflection wavelength of the resulting polymer film and obtained insights into the spatial distribution of the helical pitch.