Nano-Cluster Size Distribution Det ermination of a Polymer Electrolyte Using DSC

摘要

The cluster-size distribution in a proton exchange membrane (Nafion~(~R)117) for the Polymer Electrolyte Fuel Cell (PEFC) was determined using DSC based on the melting-temperature depression of water in the cluster. The cluster volume calculated from the integration of the cluster-size distribution was reduced with the increasing heat treatment temperature. However, the volume recovered by immersing the membrane in hot water at 120℃ for at least 2 hrs, which could also be correlated to the increase in the ion-exchange capacity. The increase in the cluster volume suggests that a phase separation between the hydrophilic and hydrophobic groups takes place in hot water. It was confirmed that thermoporosimetry could be a powerful technique to investigate the cluster structure in the membrane for PEFCs.