Unperturbed dimensions of polyvinylpyrrolidone in pure solvents and in binary mixtures

The properties of dilute solutions of polyvinylpyrrolidone in various solvents are studied by measurements of viscosity and osmotic pressure. The unperturbed dimensions are determined in two theta solvents, in good solvents and in solvent mixtures. The existence of unperturbed states which are different in pure solvents, salty/aqueous media and organic/aqueous media is discussed on the basis of the nature of the side-group interactions in the chain itself and with the solvent. The results show, in general, a variation of the unperturbed dimensions with the solvent nature.