Rational design of proton exchange membranes: perfluoro polymers with sulfonic acid and heteropoly acid functionalities

Abstract

The state of the art in the field of perfluorinated sulfonic acid (PFSA) membranes is dictated by our understanding of pure PFSA ionomer materials like Nafion®, which performs well at saturated conditions but fails at low relative humidity and high operating temperatures (80-120 C). The motivation of this study is driven by an industry need for a proton exchange membrane material which performs at these limiting conditions. In this study the functionality of the PFSA side chain is modified with the end goal of improving ion conductivity in a thermally, mechanically, and chemically stable material. Major findings of the study find the addition of functionalized heteropoly acid was unsuccessful to that end, while ion conductivty of a novel material, PolyPSA, outperformed the industry standard (Nafion®-212).