Theory of Dilute Polymer Solutions (III) Intrinsic Viscosity

Abstract

A theory of the intrinsic viscosity [η] of chain polymer solutions is developed on the basis of the Kirkwood and Riseman scheme, taking some modifications concerning the excluded volume effect into account. If the volume effect is represented by the linear expansion factor α of the root mean square radius of gyration, it is concluded that [η] is proportional to α² for the free-draining molecule and α^2.43 for the non-free-draining molecule. This implies that the effective hydrodynamic radius of the polymer coil is not proportional to the statistical one in the limit, where the rigid sphere model is asymptotically valid; in other words, the more the polymer chain is expanded, the deeper the solvent molecules penetrate into the polymer coil.