Networks and blends in liquid crystal polymer composite materials

Polymer Dispersed Liquid Crystals, PDLC, have considerable potential for various electro-optical applications such as flexible displays and switchable windows. For this reason they are the subject of active research in laboratories around the world. From a fundamental point of view, they belong to the same class as multi-component polymer mixtures and as such they present interesting phase properties. In this paper, an attempt is made to understand their phase behavior. In particular, the total free energy is examined and its implications on the phase behavior of liquid crystal - polymer composite films prepared by polymerization induced phase separation processes are discussed. The focus is put on the effects of crosslinks of the polymer matrix on the free energy and on coexisting phases when the temperature of the film and the volume fraction of the liquid crystal component are modified.