Liquid Crystalline Thermosets

Abstract

AbstractLiquid crystalline thermosets are a new class of materials currently under investigation in a number of research laboratories. Various types of these materials have been described, including liquid crystalline thermosets with epoxy, acrylate and methacrylate, maleimide and nadimide, vinyl, isocyanate and cyanate ester, and ethynyl end groups. These materials have two structural features, a cross‐linked network and liquid crystalline order, which can have a profound influence on each other. The formation of a network during the cross‐linking reaction can have a strong influence on the liquid crystalline structure of the final cured material. In addition, the liquid crystalline structure can have a strong influence on the kinetics of the cure reaction. The liquid crystalline structure also affects the properties of the cured material. For example, fracture toughness is increased and permeability to various liquids is decreased, although the nature of these changes depends on the liquid crystalline phase and the exact morphology of the system. Liquid crystalline thermosets may also be oriented using external fields, such as surfaces, electric fields, and magnetic fields. Orientation has the potential to provide a new processing route for thermosets, leading to unique properties unattainable with conventional thermosets.