Proton transfer in the interface of Nafion and sulfonated polypyrrolone

The proton conductivity at the interface of Nafion and sulfonated polypyrrolone composite membrane decreases by 56% from 0.039 S cm−1 to 0.017 S cm−1, due to phase separation after annealing this binary composite membrane at 140 °C, which is 10 °C above the glass transition temperature of Nafion polymer. After annealing the membrane, the change in the relative intensity of the lower angles of the X-ray diffraction (XRD) peaks located at ca. 11.9°, 17.5° and 19.7° indicates an increase of the low spacing region for the polymer chains of the composite membrane and atomic force microscopy (AFM) measurement depicts a morphological evolution from an uniform dispersion to a spherules micro-structure, implying the aggregation of polymer chains of the annealed composite membrane. These results are combined to reveal there is a microphase separation of this binary composite membrane as it is annealed at 140 °C.