Chemical-morphological characterizations

In this deliverable different chemical, structural and morphological characterizations of polymeric membranes and inorganic fillers is reported. In particular, the membranes were studied by XRD in dependence of hydration/ dehydration processes to address the role of water uptake on the structural stability. The results were compared with micro-Raman characterisations pointing out a general chemical stability of the materials in different hydration conditions. The chemical and electronic characterization in terms of XAS and XPS highlighted that: in the radical scavengers Ce is mainly in Ce4+ oxidation state. Ce3+ contribution increases under the X-ray due to beam damage; in proton exchange membranes AD7225-13J and AD7225-11J, Ce is mainly Ce4+ oxidation state, while in the RSP-EW-720 PEM (Syensqo) Ce is mainly 3+ oxidation state. It is not possible to detect the RSP in the PEM by XPS with Al Kα X-ray source because the concentration is below the XPS detection limit. The chemical composition of the PEM was successfully measured, and it is in agreement with PTFE structure. A homogenous distribution of the scavenger in all the PEMs was found. Regarding the morphological characterizations, a procedure to observe the original morphology of the polymer without alterations for STEM analyses was optimized. Moreover, some preliminary characterizations on surface of the membranes and on fragile fracture of membranes and MEA post operations were carried out. At the end, transport properties of the membranes were evaluated in terms of gas permeation test and conductivity test.