Polyalkylphosphazenes as solid proton conducting electrolytes

Several polydialkylphosphazenes, [P<R'R"> = N](n), R' and R" = Me, Et, Pr; Bu, hexyl, were considered for the fabrication of solid proton conducting electrolytes due to their capacity to be protonated at the chain N atom. Protonated polydipropylphosphazene (PDPrP(.)nH(+)) was found the most suitable to this purpose. The solid state proton conducting properties and structural stability of PDPrP(.)nH(+)at 1H(3)PO(4)/N mole ratio in composite materials with polyphenylensulfide (Ryton(R)) were studied by conductivity measurements in the 29-79degreesC temperature (T) and 0-33% relative humidity (RH) ranges, and by thermal analysis and NMR spectroscopy. The conductivity was found to increase upon increasing T and RH. Conductivity at 33% RH was in the same range of values reported for other polymers containing sulphonic or phosphonic acid groups. Conductivity in the dry state was in the range of values reported for polymers containing imidazole rings. NMR and conductivity data showed that upon aging in the above experimental conditions the polymer undergoes structural changes and exhibits higher conductivity.