LIQUID-CRYSTALLINE MAIN-CHAIN POLYMERS WITH A POLY(P-PHENYLENE TEREPHTHALATE) BACKBONE .8. SYNTHESIS AND CHARACTERIZATION OF POLYESTERS WITH 3-ETHOXYPROPOXY AND 6-(PENTYLOXY)HEXYLOXY SIDE-CHAINS

The influence of replacing a methylene group in the middle of the side chain of alkoxy-substituted poly(p-phenylene terephthalate)s by an ox ygen atom was investigated by differential scanning calorimetry (DSC), rheological measurements and X-ray diffraction. Due to the presence o f the oxygen atom the side chains of the polymer with long side chains (PTA12(O)HQ) lose their ability to crystallize. Except for this diffe rence and a shift of the transition temperatures to lower temperatures , this polymer shows a similar phase behaviour compared to the corresp onding alkoxy-substituted polyester PTA12HQ. The polymer with short si de chains, PTA6(O)HQ, shows a similar behaviour as the corresponding p olymer without an extra oxygen atom, PTA6HQ. Only the transition to th e nematic mesophase is shifted to lower temperatures.