Proton conductor based on poly(ethylene oxide) complexed with tetra-methyl-ammonium bromide

Proton conducting films of poly (ethylene oxide) (PEO) complexed with tetra-methyl ammonium bromide (TMABr) salt have been prepared using solution-cast method. Several experimental techniques such as infrared spectroscopy (IR), differential scanning calorimetry (DSC), composition dependent conductivity, temperature dependent conductivity over the temperature range 303–373 K and transport number measurements have been employed in order to study the characterisation and transport mechanism in these proton conducting polymer electrolyte films. DSC results reveal an endothermic peak at the temperature 70°C, which corresponds to the melting temperature of pure PEO. A slight shift in the melting point, Tm towards lower temperatures has been observed due to the addition of the salt to the polymer. The conductivity–temperature plots showed two regions in the temperature range of study. A sudden increase in conductivity at melting point (Tm) has been explained as due to a phase change from semi crystalline to an amorphous phase. The transport number data suggest that the charge transport in these films is mainly due to ions.