Phenolate anion-based branched/cross-linked poly (arylene ether sulfone) hydroxide exchange membranes

• Phenolate anion-based cross-linkage can act as efficient radical scavenger.
• The cross-linked membranes show high oxidative stability and long-term stability.
• The membranes have excellent dimensional stability and low methanol permeability.
• The membranes display reasonably high hydroxide conductivity.

Novel phenolate anion-based branched/cross-linked anion exchange membranes (AEMs) are synthesized via the quaterization reaction between poly (arylene ether sulfone) containing side-chain benzyl groups and 2,4,6-Tris(dimethylaminomethyl)phenol. The branched/cross-linked AEMs show much higher performance than the corresponding uncross-linked membrane (Q) because of branched/cross-linked structure and phenolate anion-based antioxidant structure in membrane. Among the branched/cross-linked AEMs, CQ15 with IEC of 1.25 mequiv.g−1 shows a reasonably high hydroxide conductivity of 32 mS cm−1 at 80 °C, low PM of 0.41 × 10−7 cm2 s−1, large φ of 39 × 104 Scm−3s, and display above three times of oxidative stability than Q. Meanwhile, CQ15 exhibits long-term stability against alkali treatment at 60 °C for 216 h with small reduction in hydroxide conductivity by only 16%, and also remains stable in 4 mol L−1 NaOH solution at 80 °C for 132 h with low reduction in hydroxide conductivity by 20%, indicating high potential application for anion exchange membrane fuel cell.