Synthesis and properties of long-chain-branched poly(aryl ether sulfone)-poly(tetrahydrofuran) multiblock copolymers

Long-chain-branched poly(aryl ether sulfone)-poly(tetrahydrofuran) multiblock copolymers (PES-BPTHF) composed of hard linear and soft branching segments were synthesized from bromo-terminated poly(tetrahydrofuran) and hydroxy-terminated poly(aryl ether sulfone). A study on the effect of concentration on polymerization behavior revealed that soluble powder was obtained at the optimized reaction concentration of 7 wt%. Gelation and intramolecular cyclization were observed at high and low concentrations, respectively. The microphase-separated morphology of PES-BPTHF was confirmed by atomic force microscopy, small-angle X-ray scattering (SAXS), and dynamic mechanical analysis (DMA) measurements. Fewer entangled poly(tetrahydrofuran) segments were detected in PES-BPTHF than in PES-PTHF by SAXS, DMA and tensile measurements. Rheological measurements suggested high chain entanglement of PES-BPTHF in its melt phase. It is interesting to note that the polymer chains in the soft domains become less entangled and more reminiscent of hyperbranched architectures, whereas the overall chain entanglements are increased due to the long-chain-branched structure.