Synthesis of PEEK/PSU Multiblock Copolymers

Abstract

The goal of the work presented here was to synthesize multiblock copolymers based on transesterification polycondensation of end group functionalized PEEK with PSU oligomers in the melt. In the synthesis of PEEK oligomers by nucleophilic aromatic substitution cyclization occured observed by decreasing amount of end groups. The phase behavior of the multiblock copolymers was examined by differential scanning calorimetry and transmission electron microscopy and a phase diagram was constructed. The experimental results were compared with spinodals calculated by Mean Field Modelling. It could be shown that the very similar structure of the blocks and the insufficient high block molecular weights were responsible for the observed non-phase separated morphologies. The thermal properties of the multiblock copolymers can be controlled by the segment length of the PSU oligomers. The glass transition temperature is increased provided that the segment length of PSU oligomers is lower than 8000 g mol−1