Main chain thermotropic polyesters having flexible spacers—influence of ester group linking order between mesogenic unit and flexible spacer

Two series of main chain thermotropic polyesters having a decamethylene spacer were prepared and their thermal transitions and liquid crystalline properties were studied. The linking sequence of the ester bond between the mesogenic unit and spacer, i.e., versus with M and S being mesogenic unit and spacer, respectively, was found to influence profoundly the nature of the mesophase formed by the polymers. The former favors the formation of a smectic phase, while the latter favors the formation of a nematic phase. The structure of the central dicarboxylic acid moiety of the triester mesogenic units also was found to influence greatly the polymer's ability to form mesophases.