Wittig reaction constructed an alkaline stable anion exchange membrane

Abstract

Pendant type anion exchange membranes are currently believed to the state of the art membrane due to enhanced stability. Yet, challenge lies in the limited strategy to construct such structure. Herein, pendant type anion exchange membranes with flexible quaternary ammonium groups attached to poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) backbone via length-tunable spacers were successfully prepared by mild and one-pot Wittig reaction. The as-prepared membranes show restricted water swelling, high hydroxide conductivity and low methanol permeability at low ion exchange capacity due to spacer induced microphase separation. Among them, QPPO-SC6 exhibits highest hydroxide conductivity (from 37.6 mS/cm at 20°C to 99.5mS/cm at 80°C) and good chemical stability in alkaline environment at 80°C. The mechanical and thermal properties of these membranes were also investigated. Results prove that our strategy in preparing anion exchange membranes with flexible spacers has great application potential in anion exchange membrane fuel cells.