STUDIES ON THE THERMOTROPIC LIQUID-CRYSTALLINE POLYCARBONATES .2. SYNTHESIS AND PROPERTIES OF FULLY AROMATIC LIQUID-CRYSTALLINE POLYCARBONATES

Four series of fully aromatic polycarbonates were prepared by using melt polycondensation from various novel phenylene diphenyl dicarbonates: 1,4-phenylene diphenyl dicarbonate, 1,3-phenylene diphenyl dicarbonate, methyl-1,4-phenylene diphenyl dicarbonate, and chloro-1,4-phenylene diphenyl dicarbonate with various diols-4,4'-biphenyl diol, hydroquinone, 2,7-naphthalene diol and 1,5-naphthalene diol, respectively. The thermotropic liquid crystalline properties of synthesized polycarbonates were investigated by: (1) examination of the melt birefringence and stir opalescence by a polarizing microscope equipped with a heating stage, (2) characterization by a differential scanning calorimeter (DSC), and (3) analysis of the wide angle x-ray diffraction. It was found that the 1,3-phenylene unit is compensated for the nonlinearity of the carbonate group, and polycarbonates which contain this bent shape unit showed excellent wide mesophase transition in this study.