Development of Flexible and Large area Liquid Crystal Display Devices

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Composite materials consisting of polymers and low molecular weight liquid crystals (LCs) are promising materials for preparation of electro-optical devices such as displays and electrically controllable light shutters. A practical method of producing composites is by photopolymerization induced phase separation of an initially miscible solution of polymer precursor, crosslinker LCs. The performance of the composites strongly depends on the final morphology of the polymer network and the LC domains. The morphology is determined by both thermodynamics and kinetics of phase separation during the preparation processes. In this stud novel composite materials consisting of vinyl ether copolymers and LCs were prepared to develop a large-area and flexible display for addressing by simple multiplex electrodes.A bicontinuous phase separation of polymer and LCs was induced by photopolymerization of monomers solved in L Conventional (polymer/LC) composites have been poor in the multiplexing capab … More ility because of insufficient steepness of the opti transmission-electric voltage curve. A typical magnitude of steepness, V_<80>/V_5 is larger than 1.4 for conventional (polymer/L composites, where V_<80> and V_5 are 80 % transmittance voltage and 5 % transmittance voltage, respectively. In contrast, an extrem steep response was achieved for novel (vinyl ether copolymer/LCs) composites by optimizing the monomer component, the phcirradiation temperature the photo-irradiation intensity and so on. The magnitude of V_<80>/V_5 ranged 1.25 to 1.35 which can give optical contrast ratio of 30-70 at the multiplex level of 8. The mechanism of the electro-optical response was investigated based light scattering characteristics, dielectric properties, morphology rheology, polymerization kinetics and phase-separation kinetics. The timing between the occurrence of the spinodal decomposition or the viscoelastic phase separation into polymer rich and LCs-rich pha and the development of polymer network during photopolymerization of (monomers/LCs) mixture solution was a dominant factor control the electro-optical properties. Less