Nano-composite polymer gel electrolytes containing ortho-nitro benzoic acid: role of dielectric constant of solvent and fumed silica

In this paper, nano-composite polymer gel electrolytes containing polymethylmethacrylate, dimethylacetamide, diethyl carbonate, fumed silica and ortho-nitro benzoic acid have been synthesized. Electrical conductivity, viscosity, pH and thermal behavior of these electrolytes have been studied. The effect of acid, polymer, fumed silica concentration on conductivity, pH and viscosity has been discussed. The effect of dielectric constant of solvent on conductivity behavior of composite polymer gel electrolytes has also been studied. Two maxima in conductivity behavior have been observed with fumed silica concentration for composite polymer gel electrolytes, which have been explained on the basis of double percolation threshold model. Maximum conductivity of 3.20 x 10(-4) and 2.46 x 10(-6) S/cm at room temperature has been observed for nano-composite polymer gel electrolytes containing 10 wt% polymethylmethacrylate in 1 M solution of o-nitro benzoic acid in dimethylacetamide and diethyl carbonate respectively. The intensity of first maximum observed in conductivity at low concentration of fumed silica has been found to decrease with the decrease in acid concentration for composite polymer gel electrolytes, while the intensity of second maximum at higher fumed silica concentration remains unaffected. The conductivity of composite gels does not show much change in the temperature range of 20-100 degrees C and also remains constant with time, making them suitable for use as electrolytes in various devices like fuel cells, proton batteries, electrochromic window applications etc.