ELECTROOPTICAL STUDY OF NEMATIC ELASTOMER GELS

We report on an electro-optical study of a liquid-crystal-polymer comp osite system. This system is made by dissolving a small amount of acry late monomers (8%) plus crosslinkers in a nematic liquid crystal, and then photopolymerizing the homogeneous mixture. These nematic gels sho w properties different from those of ordinary nematics or polymer stab ilized liquid crystals. By studying the electric field induced Frederi ks transition, some basic propel-ties of the nematic gels can be deduc ed. We compare the experimental results to a simple phenomenological m odel of the nematic gel, involving a characteristic length scale of or der 1 mu m, which is also visible as speckles, an effective internal a ligning field of a few statvolts per cm, and an increased rotational v iscosity on the order of 10(4) P. We indicate how a microscopic model might relate the first two of these parameters.