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 unde rgoing circular Couette flow, were measured by flow light scattering (FLS) techniques. Analysis of the angular dissymmetry of the scattered light inte nsity allowed the determination of polymer chain alignment in the flow dire ction, as well as a direct measurement of chain dimensions. The polymers we re dissolved in several different solvents to determine the effect of solve nt quality on polymer coil conformation under shear. The polymer solutions all consisted of a nearly monodisperse polystyrene sample of 3 x 10(6) g/mo l molecular weight dissolved in various viscous solvents, including tricres yl phosphate, dioctyl phthalate, and a mixed solvent of low molecular weigh t polystyrene (M-w = 5780 g/mol) and dioctyl phthalate. There was a pronoun ced dependence of chain conformation on the quality of the solvent, with po orer solvents allowing more orientation of the polymers with the flow direc tion, as well as larger relative deformations. (C) 1999 Elsevier Science Lt d. All rights reserved.