TITLE:
Effects of Molar Ratios of Thiol-Ene Monomers on the Morphology and Electro-Optical Properties of Polymer Dispersed Liquid Crystal Films
AUTHORS:
Su-Cheol Park, Jung-Dae Cho, Jin-Who Hong
KEYWORDS:
Photopolymerization; PDLC; Thiol-Ene; Stoichiometry; Driving Voltage
JOURNAL NAME:
Open Journal of Organic Polymer Materials,
Vol.3 No.4,
October
22,
2013
ABSTRACT: We synthesized tetrafunctional allyl ether monomer
(4-AE) and investigated the effects of the different molar ratios of
trimethylolpropane tris-(3-mercaptopropionate) (3-SH) to 4-AE on the
photopolymerization behavior, morphology, and electro-optical properties of
thiol-ene-based PDLC films. Photo-DSC and DSC analyses revealed that the PDLC
sample containing 45 wt% 3-SH and 45 wt% 4-AE gave the highest exotherm, the
fastest photocure rate, and the highest Tg due to the matched stoichiometry. Morphological observations and
electro-optical measurements showed that the PDLC sample with the matched molar
ratio gave the smallest LC droplet size, the highest threshold, driving voltages,
and lowest saturation transmittance because the orientation of LC molecules got difficulty in small droplets. The stoichiometric ratios of
3-SH to 4-AE played an important role in controlling the photocure rate, phase
separation rate, microstructures of LC droplets, and electro-optical
properties of thiol-ene-based PDLC systems.