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STATEMENT OF PROBLEM Our objective for this project is to understand the relationship between molecular structure and physical properties in liquid crystalline thermosets (LCT's). In particular, we have measured the effects of changes in structure on thermal transitions, gelation, mechanical properties, and transport properties. Conventional thermosets, such as epoxies and vinyl esters, are used extensively as structural materials, adhesives, and in many other applications. Their use is limited, however, by their inherent brittleness, low strength, and permeability to gases and moisture. In contrast, liquid crystalline polymers (LCP's) are known for their high strength, good fracture toughness, and good barrier properties. LCT's combine the beneficial properties of LCP's with the processing advantages of conventional thermosets. Thus, LCT's have potential as a new class of thermoset materials with improved chemical resistance, resistance to environmental changes, and enhanced mechanical properties. For example, use of LCT's in composites will result in structures that are more damage tolerant, that have reduced weight with increased strength, and that can better resist environmentally induced failure. The molecular ordering inherent in a liquid crystalline phase could also lead to self-assembled structures based on LCT's that have novel electronic and optical properties. Thus, LCT's have the potential to be recognized as a new material with unique properties. This work provides the basis for understanding these properties. variables as well, except in the case of fully saturated DOMS/SAA, where there is no indication that an interaction effect exists. PUBLICATIONS Peer Reviewed Publications Seunghyun Cho and Elliot P. Douglas, "Gelation and the development of liquid crystalline order during cure of a rigid rod epoxy", Macromolecules, 2002, 35, 4550-4552 V. Ambrogi, C. Carfagna, M. Giamberini, E. Amendola, and E. P. Douglas, "Liquid crystalline vinyl ester resins for structural adhesives",., "The effect of stoichiometry on the fracture toughness of a liquid crystalline epoxy", Polymer Engineering and Science, 2002, 42, 269-279 Arthur J. Gavrin and Elliot P. Douglas, "Isothermal curing of acetylene functionalized liquid crystalline thermoset monomers", Macromolecules, 2001, 34, 5876-5884 Arthur J. Gavrin, Christine L. Curts, and Elliot P. Douglas, "High temperature stability of a novel phenylethynyl liquid crystalline thermoset",