EFFECT OF UREAS ON THE HYDROPHOBIC PROPERTIES OF AQUEOUS POLY(ETHYLENE OXIDE) SOLUTIONS BY VISCOMETRY

Poly(ethylene oxide) (PEG) in aqueous solutions has a hydrophobic char acter which can induce the hydrophobic interaction between its nonpola r parts. The hydrophobic properties of aqueous PEO solutions are studi ed by the viscometry in terms of the water structure-making and -break ing capabilities of added solutes of ureas, The results show that the contracted conformation of PEO of low molecular weight, namely poly(et hylene glycol) (PEG), does not result from the hydrophobic interaction between the nonpolar parts of PEO but it can participate in a hydroph obic interaction between the nonpolar parts of PEO and added ureas sol utes with nonpolar groups, which can induce a large hydrodynamic volum e and increase the viscosity. On the other hand, the PEG of large mole cular weight seems to behave like any other water soluble polymers wit h nonpolar parts and its conformation in aqueous solutions is well exp lained in terms of water structure perturbing capabilities of added ur eas.