The correlation properties of poly(vinylpyrrolidone) in N,N-dimethylformamide + water by conductometric study

The electrical conductivity of solutions of poly(vinylpyrrolidone) (PVP) in N,N-dimethylformamide + water (DMF/W) over a wide range of concentrations and at different temperatures was measured. Polymer solutions exhibit a critical concentration c**, separating dilute solutions into extremely dilute solutions and dilute solutions. The electrical conductivity–temperature dependence is discussed on the basis of a modified formula of the correlation between the true and the experimental relative electrical conductivity. The polymeric solutes are readily adsorbed on the wall surface of conductometer, which greatly influences the electrical conductivity measurement of the polymer solution, and results in the apparent abnormal conductivity behavior. The intrinsic electrical conductivity [σ] and the Huggins constant kH, were calculated. The solute adsorption behaviors and structural information of the polymer were discussed carefully.