Structural Colors Based on Tunable Cholesteric Liquid Crystal Polymers

Abstract

Different from traditional absorption-based pigments structural colors with the advantage of high stability of heat and light are the most promising sources of colorants now Cholesteric liquid crystals a kind of one-dimensional photonics exhibiting Bragg reflection show structural colors with aligned processing and appropriate recipe of the components To fabricate structural colors cholesteric liquid crystals (CLCs) were used as the key materials including the mixtures of nematic LC (RM257) chiral dopant (CB15) bifunctional monomer 4 4’-bis((6-acryloyloxy) hexyloxy) biphenyl (BHAB) and photoinitiator (Irgacure-184) Bragg reflection of selective light wavelength of the fabricated CLC films were confirmed by UV-vis spectrometry In addition the reflection band wavelength of the CLC mixtures was tuned by adding different amount of chiral dopant Various structural colored patterns were fabricated via the predesigned CLC mixtures through a pre-fabricated masks with UV irradiation To develop structural colorants the synthesized CLC films were cut into small slices Considering the resolution of printing image fabrication of CLC nanoparticles is necessary However in the case of ground particles light scattering and diffraction of nanoparticles results in opaque appearance and the disappearance of structural colors To show Bragg reflection slice construction is also necessary To evidence the possibility of using the synthesized CLC films as colorants the prepared CLC slices were fixed by polymer binders After printing of the prepared CLC paste various colored patterns were observed Theoretically preparation of nano-sized CLC slices via laser technique is possible The results suggest that the nano-sized CLC slices are available for the design of structure colorants

Date of Award	2020
Original language	English
Supervisor	Jui-Hsiang Liu (Supervisor)