Solution behavior of Na sulfonated polystyrene: Dipole moment determinations

Solution behavior of Na sulfonated polystyrene (NaSPS) ionomers with different percentages of sulfonate was studied by viscosity and dipole moment measurements. Two solvents of different character were chosen, i.e. dioxane (? = 2.22) and dimethyl formamide (DMF, ? = 36) and their mixtures. The reduced viscosity as a function of concentration in polar solvents reflects the ‘polyelectrolyte’ behaviour of the ionomers. Mean-squared dipole moment (<μ²>/x) values were calculated over a temperature range of 20–100°C, in dioxane and in a mixture of 4% DMF in dioxane. The results confirm the ‘polyelectrolyte’ behavior of ionomers by the addition of a small amount of polar cosolvent. The effect of increasing temperature on <μ²>/x in the DMF-dioxane mixture is attributed to the formation of a coordination complex.