Electrically and photochemically induced light scattering behavior of anisotropic polymer liquid crystal composite films

Anisotropic polymer/liquid crystal composite films containing azobenzene molecules were prepared by thermal polymerization of liquid crystalline mixtures at a nematic phase in a homogeneous glass cell. The polymer network was transparent because of its macroscopic uniaxial alignment. Upon photoirradiation to cause trans-cis photoisomerization of azobenzene molecules, the polymer network became translucent even at room temperature. The system does not require the use of polarizers and electrodes to fabricate optical devices. The light scattering is ascribed to a biphase morphology in the system produced transiently by means of the photochemical phase transition. Flexible polymer chains are responsible for the photochemically light scattering of the composite films.