Abstract
The hydrodynamic properties of near-monodisperse polystyrene (PS) in 2-butanone have been studied by photon-correlation spectroscopy and viscometry. The derived translational diffusion coefficients D0 and intrinsic viscosities [η], along with literature data for the second virial coefficient A2, have been used to calculate the corresponding equivalent sphere radii: Rh, Rv, and Rt (hydrodynamic, viscometric, and thermodynamic radii, respectively). Various ratios of these radii and ratios of the equivalent sphere radii with the radius of gyration Rg have been used to test theoretical predictions of dilute-solution behavior for linear chains. Of particular note is the observed strong variation of the ratio Rv/RH with the specific nature of the polymer/solvent system. We tentatively attribute this behavior to crossover effects and, possibly, to changes in the average shape of the chain (from more spherical to more elliptical) brought about by specific polymer-solvent interactions. © 1991, American Chemical Society. All rights reserved.