(130e) Nematic Liquid Crystal Phases Observed in Ionic Liquid Crystal Polyurethane-Ureas

Reacting the ionic chain extender DBS with an isocyanate prepolymer unexpectedly produced liquid crystal polyurethane-ureas (PUUs), which each display characteristics of a distinct monotropic nematic phase upon slow cooling, which is a rare mesophase in ionic liquid crystals. Phase transition temperatures and morphology of these thermotropic liquid crystal PUUs were determined by hot-stage optical polarizing microscopy, FTIR, CP/MAS 13C NMR, VPO, DSC, and TG/DTA. The proposed liquid crystal phase and the influence of the ionomer structure in each PUU are discussed in detail. The PUU texture is dependent upon the PUU isocyanate; HDI and IPDI polymers have nematic schlieren textures, whereas TDI and MDI polymers show nematic grain textures.