Cross-linked poly(arylene ether sulfone)s with side-chain aromatic benzyltrimethyl ammonium for anion-exchange membranes

New poly(arylene ether sulfone) (PAES)-based anion-exchange membranes with side-chain aromatic benzyltrimethyl ammonium are synthesized, and their cross-linked membranes are prepared using tetramethyl alkylene diamine as a cross-linking agent. The new side-chain-type PAES-based membrane (Q) has acceptable hydroxide conductivity (σ) of 34 mS cm⁻¹ (80 °C) and high chemical stability in hot alkali solution. Compared with Q, the corresponding series of cross-linked membranes exhibit much higher performance, such as higher dimensional stability and chemical stability, better oxidative stability, and lower methanol permeability (P _M). Among them, N,N,N′,N′-tetramethyl-1,6-diaminohexane-based cross-linked membrane (6CQ20) with IEC of 1.29 meq g⁻¹ shows reasonably high σ of 35 mS cm⁻¹ (80 °C) and low P _M of 0.20 × 10⁻⁶ cm² s⁻¹, and displays high alkaline stability against alkali treatment at 60 °C for 216 h with small reduction in hydroxide conductivity by only 14%.