Preparation of holographic gratings of liquid crystals dispersed in polyurethane acrylates under controlled reaction conditions.
Transmission gratings of holographic polymer-dispersed liquid crystals (HPDLC) are prepared under controlled reaction conditions by adding various amounts of chain-transfer agent (CTA). The resulting films have a higher gel content with lower cross-link density, less dark reaction, less grating shrinkage with much smoother LC/polymer interfaces, smaller induction period, and fast saturation of diffraction efficiency, which shows a maximum of 95 % with 1 % CTA. An optimum LC content of 35 % is verified on the basis of morphology and reaction kinetics.
Kim
Eun Hee
EH
Dept. of Polymer Science and Engineering Pusan National University, Pusan 609-735, Korea. bkkim@pnu.edu
Kim
Byung Kyu
BK