SYNTHESIS AND THERMAL-PROPERTIES OF SEMIRIGID HOMOPOLYCARBONATES, COPOLYCARBONATES AND TERPOLYCARBONATES COMPRISING NAPHTHALENE RING

Semi-rigid homopolycarbonates comprising only naphthalene ring in the repeating unit, copolycarbonates composed of the naphthalene and dimet hylsiloxane linkage and terpolycarbonates made up of the naphthalene, the dimethylsiloxane and biphenyl unit were prepared by melt polyconde nsation from a dioxydihexanol of the naphthalene, a diol of the dimeth ylsiloxane and/or a dioxydihexanol of biphenyl, and alkylene diphenyl dicarbonates having various alkylene spacer lengths. These polymers ha d good solubilities in chloroform. Thermal and liquid crystalline (LC) properties of the resulting polymers were evaluated by differential s canning calorimetry (DSC), polarizing microscope observation of optica l textures and powder X-ray analyses at various temperatures. These me asurements described that the home- and copolycarbonates displayed the rmotropic nematic plases in spite of low aspect ratio of the naphthale ne ring. The terpolymers had no well-defined textures. Phase transitio n temperatures in the home- and copolycarbonates decreased with increa se of alkylene spacer lengths without showing odd-even fluctuation. Th e copolymers exhibited lower phase transition temperatures and wider L C temperature ranges than the homopolymers. All the polycarbonates pos sessed very low glass transition steps below room temperature.