Anisotropic networks, elastomers and gels

Anisotropic networks, elastomers and gels exhibit piezoelectric, pyroelectric, ferroelectric and NLO properties of potential interest for use in many electro-optic devices for optical communication and processing technologies. The formation, properties and applications of such anisotropic, mainly liquid crystalline, networks are described. If some of the molecules in a liquid mixture contain at least two reactive groups which can be either photochemically or thermally polymerized, then crosslinked, anisotropic networks, elastomers and gels can be produced. Solid macroscopically aligned elastomers or networks can be formed as required beforehand or simultaneously by orientation of the sample. Anisotropic gels consist of a solid anisotropic network and non-covalently bonded, but strongly oriented domains of low molar mass liquid crystals. Anisotropic networks, elastomers and gels can be prepared from preformed amorphous or liquid crystalline polymers incorporating additional reactive groups, which can be macroscopically oriented in the liquid crystalline state and then fixed by additional crosslinking reactions. Reversible networks, elastomers and gels can be prepared either non-covalently or covalently by thermally reversible linkages between, for example, side group polymers and low molar mass molecules, neither of which necessarily exhibit liquid crystalline properties in the pure state.