LIQUID-CRYSTALLINE FLUOROCARBON SIDE-CHAIN POLYESTERS

Perfluoroalkyl side-chain polyesters of the type -[O(CH2)2N{SO2(CF2)8F }(CH2)2O2C(CH2)m-CO]n-, with m = 2-4, 8, 12, and 20, have been synthes ized in high yield directly from the diacid and the diol, using a coup ling agent. Molecular weights up to 40 000 were obtained. The polyeste rs with m > 3 showed enantiotropic mesophases, although they have no f lexible spacer between the main chain and the side-group mesogen. The rigid perfluoroalkylsulfonamide, group and the segregating tendency of fluorocarbons and hydrocarbons give these polyesters their liquid cry stalline behavior. The mesophases were investigated by polarizing opti cal microscopy, DSC, and rheological DMA. They have a grainy optical t exture in the POM, multiple transitions in the DSC and a low-viscosity mesophase regime in mechanical analysis.