Fabrication Of LC/Polymer Composites And Research On Effect Of Polymer Network On Electro-Optical Properties

Polymer/liquid crystals (LC) composite films have attracted increasing interest over the last years due to wide application range from information display to switchable window. Based on the morphologies, two types of liquid crystal polymer dispersions have been developed. The first type is the polymer dispersed liquid crystals (PDLC), in which LC usually represents more than 30% and LC droplets dispersed in polymer matrix; the second type is the polymer stabilized liquid crystal (PSLC), in which LC usually represents lower than 10% and LC becomes continuous phase and three-dimensional polymer networks are dispersed in liquid crystals. We have adopted different mono-functional and bi-functional monomers to fabricate polymer/LC composites of PDLC and a kind of PSLC, investigated effect of monomer structures and polymerization temperatures on their electro-optical properties and microstructures.In this study, we have prepared PDLC films using Polymer Induced Phase Separation (PIPS) through free-radical polymerization, and studied the influence of crosslinking degree of polymer network and monomer structure on PDLC's electro-optical properties. SEM photos are then been analyzed. The structure of mono-functional monomers is the key factor in influence of morphology and electro-optical properties. Second, we have fabricate a new mode called polymer stabilized isotropic liquid crystal (PSI mode LC). Effect of monomer structure and polymerization temperature is investigated. We can see different microstructures compared with PDLC, and PSI mode LC fabricated by mono-functional monomers with flexible molecular chain exhibit good electro-optical properties. Third, we have prepared PDLC films through cationic polymerization system and hybrid system mixing free-radical and cationic polymerization, also investigated problems emerged from these two systems.