Osmotic, viscometric and light scattering studies of polymers dissolved in a mixture of two non-solvents (cosolvents)

Abstract

Polystyrene has been found to be completely soluble in the following binary mixture of non-solvents, viz. nitrobenzene and acetone, heptane and acetone, cyclohexane and acetone, nitrobenzene and diethyl oxalate, hexane and diethyl oxalate, cyclohexane and diethyl oxalate. Polymethyl methacrylate has similarly been found to be soluble in carbon tetrachloride and methanol, and in carbon tetrachloride and ethanol. These two polymers have been studied viscometrically, osmometrically and with respect to light scattering property. An optimum composition with a minimum in osmotic μvalue and viscometric Huggins constant, a maximum in [η]-value and a maximum in dissymmetry coefficient has been found to exist. The above observations are considered to indicate that the composition showing maximum solvent power is a true optimum composition and the dissolved unit is laterally more extended in this optimum composition than at any other composition of the two non-solvents. Five samples of polymers have been studied in a number of ø-mixtures near room temperature with a view to obtain the K_ø values of Flory-Fox equation, [η]ø=K_ø M^-_v^0.5. It has been found that K_ø values vary widely with the chemical nature of the theta mixture indicating solvent dependency of unperturbed polymer dimension.