Block poly(arylene ether sulfone) copolymers bearing quaterinized aromatic pendants: Synthesis, property and stability

Block poly(arylene ether sulfone) copolymers caring pendent benzyl-quaternary ammonium groups were prepared through multiple-step reaction pathways that involve pre-polycondensation, block copolycondensation, bromomethylation and Menshutkin reactions. The copolymer ionomer based anion exchange membranes (AEMs) with ion exchange capacity (IEC) from 0.75 to 1.10 mequiv g−1 display relatively large hydroxide conductivities of 45.9-66.1 mS cm−1 at 80 °C, which are ascribed to the distinct hydrophobic/hydrophilic microphase separation resulted from the block copolymer structures and side-chain type hydrophilic segments. Compared to the corresponding random copolymer based AEM, the block ones have obviously higher stability and larger hydroxide conductivity due to the well-connected ionic nanochannels. Among the AEMs, bQPAE-x7y32 with IEC of 1.10 mequiv g−1 gives the best performance with high hydroxide conductivity of 66.1 mS cm−1, low methanol permeability of 4.9 × 10−7 cm2 s−1, large φ of 4.6 × 104 Scm−3 s, as well as good alkaline stability, respectively.