Fabrication and Optical Characterization of Broad-Band Photonic Films Induced via Photopolymerization

Abstract

Fabrication of broadband cholesteric liquid crystal imprinted cell by controlling photopolymerization has been performed The broad band Bragg reflection cholesteric liquid crystal cells have been achieved by using UV bleachable dye temperature variance photopolymerization process etc In this study imprinting and broadening of reflection band of cholesteric liquid crystal cells were achieved via controlling UV polymerization Intensity gradient of UV light was achieved by adjusting the distance between UV lamp and the sample cell Imprinted template was prepared by photopolymerization of mixed nematic LC (HSG22200) chiral dopant (CB15) bifunctional monomer 4 4’-Bis((6-acryloyloxy) hexyloxy)biphenyl (BHAB) and photoinitiator (Irgacure-184) Intensity of UV light may affect the polymerization rate leads to the formation of imprinted helical construction with different pitches Pitch gradient inside the systems usually broaden the reflection band of sample cells effectively After polymerization the residual liquid crystal mixture was then removed by using solvent Refilling of nematic liquid crystal increases refractive indexes leads to the enhancement of reflection light of sample cells Stacking of two imprinted cells with different pitches broadens reflection band effectively In this study comparison of this new designed process with traditional UV polymerization process was carried out Spectral characterizations and optical reflection of sample cells were performed using fiber optic spectrometer

Date of Award	2016 Jul 15
Original language	English
Supervisor	Jui-Hsiang Liu (Supervisor)