Anion Exchange Membranes: Enhancement by Addition of Unfunctionalized Triptycene Poly(Ether Sulfone)s

Abstract

Anion exchange membrane fuel cells are a clean and efficient promising future energy source. However, the development of stable high-performance membranes remains a major challenge. Herein we demonstrate that the addition of unfunctionalized triptycene poly(ether sulfones) into 1-methylimidazolium poly(ether sulfone) enhances membrane's conductivity (up to 0.082 S/cm at 80 °C), minimizes dimensional changes over temperatures from 20 to 80 °C, and enhances stability with 30% of the initial conductivity maintained after 450 h. These enhancements appear to be the result of nanophase separation and internal free volume. Small angle X-ray scattering and transmission electron microscopy reveal that the internal domain size increases (up to 7.44 nm) with increasing triptycene fraction. Keywords: anion exchange membrane; hydroxide conductivity; mechanical property; phase separation; triptycene copolymer