Premium
Surfactant Effects on Morphology and Switching of Holographic PDLCs Based on Polyurethane Acrylates
Author(s) -
Woo Ju Yeon,
Kim Byung Kyu
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600482
Subject(s) - pulmonary surfactant , coalescence (physics) , dimensionless quantity , diffraction , materials science , polyurethane , polymer , solubility , diffraction efficiency , morphology (biology) , analytical chemistry (journal) , chemical engineering , chemistry , composite material , optics , thermodynamics , chromatography , organic chemistry , physics , astrobiology , genetics , biology , engineering
Effects of octanoic acid (OA) on the morphology, diffraction efficiency, and electro‐optic properties of the transmission mode of holographic polymer–dispersed liquid crystals (HPDLC) are studied. Droplet size decreases with increasing OA content (0–9 %), and this leads to a monotonic increase in off‐state diffraction with increasing OA content. However, on‐state diffraction decreases with increasing applied voltage and shows a minimum at 6 % OA, for which minimum switching voltage (5 V μm −1 ) and maximum contrast ratio (10) are obtained. Rise time and decay time decrease with increasing OA content. Interposition of OA between polymer and LC droplet is theoretically predicted by the spreading coefficient ( λ >0) calculated on the basis of the solubility parameter, while the coalescence behavior of droplets is described by a dimensionless group ( ${\gamma d\rho /\mu ^2 }$ ) called coalescence number.