Hydration Behaviour of Sufonated Polyetheretherketone (SPEEK) Membranes

Abstract

Polymer electrolyte membranes (PEM) have a potential to become power sources in automotive industry and other household applications. PEM such as sulfonated polyetheretherketone (SPEEK) have acceptable operating temperature range but proton conductivity is dependent on amount of sulfonic groups attached to the polymer backbone (degree of sulfonation). At the same time, the sulfonic groups cause sorption of water from surrounding vapour or liquid. This factor may lead to mechanical failure if membrane absorbs too much water. Modification of PEM by adding ionic liquids (IL) may provide good proton conductivity but presence of water could also be critical factor of membrane stability as in high humidity conditions IL are washed out of membrane and replaced by water molecules. PEM with IL inclusions could be potentially used at temperatures close to water boiling point and higher as IL used in this research are thermally stable in temperatures up to 200°C.