Radii of gyration and screening lengths of polystyrene in toluene as a function of concentration

Small-angle neutron scattering (SANS) experiments on solutions of polystyrene (PSH) and its deuterated homologue (PSD) in deuterated toluene have been performed over a wide range of concentration. Several redundant measurements demonstrated that the high-concentration technique of extracting single-chain scattering functions is highly reliable. Radii of gyration and screening lengths were fitted to power laws and were found to be R/sub g//sup 2/ approx. c/sup -0.156/ and xi approx. c/sup -0.70/. The results differ significantly from predictions by scaling theory, though the dependence of xi on c is in good accord with that previously found by other researchers. These experiments were also analyzed by using recent theoretical results of Muthukumar and Edwards. Measurements at different concentrations yielded a reasonably consistent value of the excluded volume interaction parameter. 41 references, 10 figures, 7 tables.