Proton transport in assemblies of silica colloidal spheres

We studied the proton transport in free-standing assemblies of surface-sulfonated silica nanospheres, either randomly packed or self-assembled into a close-packed arrangement. The transport studies were performed in the absence of solvent, under either dry or high humidity conditions. We demonstrated that colloidal assemblies prepared using surface-sulfonated silica nanospheres possess proton conductivity that depends on the ordering of the material, temperature and relative humidity. Based on the comparison between the close-packed and disordered assemblies made of the same spheres we conclude that the increase in structural organization of the self-assembled colloidal materials leads to increased proton conductivity and better water retention.