Synthesis and characterization of styrene-vinyl tetrazole copolymers for their application as a solid electrolyte

Abstract The synthesis and characterization method of a styrene-vinyl tetrazole copolymer (StVTz) at different molar ratios (50:50, 60:40, 70:30, 80:20, and 90:10) is reported. The new copolymers were prepared from a previously synthesized styrene-co-acrylonitrile copolymer, followed by a Huisgen 1,3-dipolar cycloaddition reaction to obtain the styrene-tetrazole copolymers. Copolymers were characterized by Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR) analysis, and molecular weight. Membranes were further prepared by casting method and the morphology revealed by atomic force microscopy (AFM). The thermal properties were evaluated by differential scanning calorimetry (DSC) and by thermogravimetric analysis (TGA), and ionic properties by means of ion-exchange capacity (IEC) value obtained from titration measurements and by water uptake (WU). Water content (WC) present was also determined by TGA. The electrochemical behavior was followed by Electrochemical impedance spectroscopy (EIS). Morphological analysis by atomic force microscopy demonstrates the presence of a single phase with roughness proportional to hydration. No relationship between WU, IEC, and WC with the composition of the copolymer was observed; however, a correlation between ionic conductivity and the percentage of bound water in the membrane was found. The results of ionic conductivity for copolymers envisage a potential application of this class of compounds as membranes in fuel cells.