Preparation and Proton Conductivity of Sulfonated Polymer-Modified Sintered and Self-Assembled Silica Colloidal Crystals

We prepared sintered self-assembled nanoporous silica colloidal crystals modified with poly(3-sulfopropyl-methacrylate) and poly(stryrenesulfonic acid) brushes covalently attached to the nanopore surface. The resulting robust membranes possess temperature and humidity-dependent proton conductivity of similar to 2 x 10(-2) S cm(-1) at 30 degrees C and 94% RH, similar to 1 x 10(-2) S cm(-1) at 85 degrees C and 60% RH, and water uptake of approximately 20 wt % at room temperature. We also prepared proton conductive membranes by self-assembly of silica nanospheres modified with poly(3-sulfopropylmethacrylate) and poly(stryrenesulfonic acid) brushes of different thickness. These membranes showed a slightly higher proton conductivity and water uptake but poor mechanical properties.