Functionalized poly(styrene-co-4-vinylpyridine) with industrial ionic liquid for side-chain type anion exchange membrane

To develop high-performance anion exchange membranes (AEMs) with excellent alkaline stability and high hydroxide conductivity, a series of poly(styrene-co-4-vinylpyridine) (PSD-m/n) were rationally designed and synthesized. Based on mature synthetic strategies, this work optimized a superior molecular configuration. The prepared polymers possess a flexible all-carbon backbone and adopt a side-chain grafting strategy to anchor industrial ionic liquids. Such aryl ether-free membrane architecture can effectively suppress the alkaline degradation behavior of conventional AEMs under harsh working conditions. Target quaternized AEMs (QPSD-m/n) were successfully fabricated by reacting PSD-m/n with an industrial ionic liquid 3-Bromo-N,N,N-trimethylpropan-1-aminium bromide (abbreviated as BTPA, counterion: Br − ). The content of pyridine-functionalized segments in the polymer backbone was precisely tailored by adjusting the molar feed ratio of styrene to 4-vinylpyridine, enabling a systematic investigation of the membrane structure-property relationship. The optimized QPSD-m/n AEMs exhibit desirable ion exchange capacity (IEC) of 1.53-2.13 meq g −1 , show low water uptake (WU) (15.22-31.03%) and restrict swelling ratio (SR) (10.11-23.90%) at 80 °C. The membranes achieve a high hydroxide conductivity of 58.32-90.06 mS cm −1 at 80 °C under test conditions. Moreover, the QPSD-m/n AEMs possess excellent thermal stability and optimizable alkaline durability. This work demonstrates that the QPSD-m/n membranes exhibit favorable performance and hold promising application prospects.