THERMOTROPIC BLOCK-COPOLYMERS - POLYESTERS WITH FLEXIBLE POLY(TETRAMETHYLENE GLYCOL) UNITS IN THE MAIN-CHAIN

Block copolymers with poly(tetramethylene glycol) (PTMG) spacers of di fferent length and the 4,4'-(terephthaloyldioxy) dibenzoyl unit have b een synthesized by high temperature solution polycondensation. The inf luence of the spacer length on thermal behaviour and solid phase struc ture of alternating polyesters in comparison with pure PTMG has been d etermined by d.s.c. and WAXS investigations. Up to spacer molecular we ights of 650 g mol-1 (degree of polymerization, DPBAR almost-equal-to 9), polymers with thermotropic liquid crystalline phase behaviour are obtained. Above spacer molecular weights of 1000 g mol-1 (DPBAR almost -equal-to 14), the coexistence of two crystalline phases resulting in polymers with block-like character is discussed.