Functional polymers and sequential copolymers by phase transfer catalysis, 20. Synthesis of copolymers and alternating block copolymers containing thermotropic liquid crystalline polyethers and aromatic poly(ether sulfone) segments

Abstract

AbstractCopolymers and alternating block copolymers were prepared both containing a liquid crystalline (LC) polyether segment, based on 4,4′‐biphenyldiol (3) and 1,5‐dibromopentane (2), and a thermoplastic segment, deriving from an aromatic poly(ether sulfone) (PSU) (1). The alternating block copolymer was prepared by the phase transfer catalyzed (PTC) polyetherification of mesogenic α,ω‐bis(5‐bromopentoxy)polyether (5) with α,ω‐bis(hydroxyphenyl)PSU (1). Copolymers containing mesogenic segments were prepared utilizing α,ω‐bis(hydroxyphenyl)‐PSU as another diphenol in the PTC polyetherification of 5 with 2 and 3. The thermal behavior, as characterized by differential scanning calorimetry (DSC), revealed phase separation for all prepared copolymers as well as liquid crystalline behavior down to a content of mesogenic units deriving from 5 as low as 30 wt.‐%. Optical polarization microscopy, however, revealed significant differences in textures of the copolymers with the textures observed for homopolymer 5. Textures of a 5/PSU blend clearly show phase separation.