Interplay between Electrical Relaxation and Structural Properties in Hybrid Membrane Based on PVDF-HFP and Functionalized Silica Network

The description of the proton transport in multi scale hybrid membrane in their dry state and at various temperatures was performed by using broadband dielectric spectroscopy. Permittivity and conductivity have been measured on a wide frequency range from a few hertz to microwaves. We found that the proton transport is multiscale, and different electrical relaxations are evidenced, resulting from the polarizations at the different length scales of the hybrid membrane. When the frequency increases, four dielectric relaxations are detected due to (a) polarization of silica domains in micronic scale, (b) polarization in the micronic silica domain, (c) polarization of silica oblong (nanometric range) forming the micronic silica domain, and finally (d) polarization of -SO3H groups distributed in the silica network (angstroms scale). Thus, this experiment confirms that the ionic transport is severely restricted to the organization of the silica network.