Thermotropic liquid crystalline polymers with low thermal transitions. I. Low melting thermotropic liquid crystalline homo‐ and co‐polycarbonates

Due to the particular rheological properties of thermotropic liquid crystalline polymers (TLCP), their application for imaging technology has been investigated. The first class of polymers investigated in this study are the thermotropic liquid crystalline polycarbonates prepared from the solution polycondensation of p,p‐dihydroxybiphenyl with bischloroformate as the aliphatic flexible spacer. From the variety of bischloroformates employed, smectic TLCP's were generally obtained with the possible presence of a nematic mesostate. The introduction of comonomers such as substituted hydroquinones or bisphenols were found to lower both the melting transitions and mesophasic range of the TLCP. From rheological characterization, the amount of nonmesogenic moieties present in the copolycarbonates were found to correlate with the increase in the melt viscosity of TLCP.