Proton conductivity of poly(dialkyl)phosphazenes–phosphoric acid composites at low humidity

New composite free standing films were fabricated by solution casting poly(diethyl, dipropyl)phosphazene, phosphoric acid and a naphthalenic sulfonated copolyimide. The proton conductivity data in dry environment obtained for these films allow to conclude that the presence of strong sulfonic acid proton donors and of phosphazene N proton acceptor sites is not sufficient to allow good conductivity in dry environment, and that the content of phosphoric acid appears the most critical factor for the proton mobility.