Time dependence of the luminescence from a polymer membrane swollen in water: Concentration and isotopic effects

Abstract

The effect of UV irradiation of the surface of a Nafion polymer electrolyte membrane swollen in water in the pump grazing incidence geometry has been experimentally investigated. The photoluminescence from the Nafion surface has been measured in the spectral range characteristic of this polymer. The photoluminescence signal from a polymer with a variable isotopic composition is found to be sensitive to swelling in water. The spectral absorption lines of dry and water-swollen Nafion samples are characterized. It is shown that the luminescence centers in the polymer are sulfonic acid groups located on the ends of perfluorovinyl ether groups, which form the teflon base. Measurements of the temporal dynamics of the luminescence of these groups have revealed an informationally important and significant dependence of the luminescence parameters on the degree of Nafion swelling. A pronounced and nontrivial dependence of these parameters on the content of heavy isotope D₂O in water is also found.