Flow light scattering studies of polymer coil conformation in solutions under shear: effect of solvent quality

The orientation and deformation of polymer chains, in dilute solutions undergoing circular Couette flow, were measured by flow light scattering (FLS) techniques. Analysis of the angular dissymmetry of the scattered light intensity allowed the determination of polymer chain alignment in the flow direction, as well as a direct measurement of chain dimensions. The polymers were dissolved in several different solvents to determine the effect of solvent quality on polymer coil conformation under shear. The polymer solutions all consisted of a nearly monodisperse polystyrene sample of 3 x 10(6) g/mol molecular weight dissolved in various viscous solvents, including tricresyl phosphate, dioctyl phthalate, and a mixed solvent of low molecular weight polystyrene (M-w = 5780 g/mol) and dioctyl phthalate. There was a pronounced dependence of chain conformation on the quality of the solvent, with poorer solvents allowing more orientation of the polymers with the flow direction, as well as larger relative deformations. (C) 1999 Elsevier Science Ltd. All rights reserved.