Proton-Conducting Polymer Membrane Consisting of Cross-Linked Poly(2-hydroxyethyl methacrylate) with Nafion® for Fuel Cell Application.

To increase the water retention and proton-conducting ability of Nafion®, we prepared a cross-linked polymer consisting of poly(2-hydroxyethyl methacrylate) (pHEMA) and Nafion®. pHEMA was chosen as a cross-linking polymer because it produces a water-insoluble but water-swellable polymer. Although it is hydrophobic, its water-swellable characteristic means that water will not be excluded from the polymer. Introduction of pHEMA into Nafion® prevents polymer solubility and provides structural stability and rigidity, which should in turn reduce the methanol permeability. Moreover, convenient permeability of pHEMA to cations makes it a good candidate for a hydrocarbon proton-conducting polymer tuned with Nafion®.