SEMIRIGID THERMOTROPIC LIQUID-CRYSTALLINE COPOLYCARBONATES COMPRISINGMAIN-CHAIN HEXAFLUOROPENTANE SEGMENTS

Novel semi-rigid fluorocarbon-containing coplycarbonates composed of b iphenyl moiety and rigid rod-like hexafluoropentane chain were prepare d by melt polycondensation of 6,6'-(biphenyl-4,4'-diyldioxy)dihexanol (1) and 2,2,3,3,4,4-hexafluoro-1,5-pentanediol (2) with alkylene diphe nyl dicarbonates 3 of various aliphatic lengths (m = 6, 8, 10 and 12). The structures of the copolymers 4 were confirmed by FT-IR, H-1 and C -13 NMR spectra and elemental analyses. The thermal and liquid-crystal line (LC) properties were examined by differential scanning calorimetr y (DSC), polarizing microscopy and temperature-changeable X-ray analys es. These measurements indicated that the copolymers show well-defined thermotropic nematic textures and have blocklike sequences. It is sug gested that the introduction of the hexafluoropentane chain into the m ain chain gives more stable LC phases.