Concentration dependence of radius of gyration of sodium poly(styrenesulfonate) over a wide range of concentration studied by small-angle neutron scattering

Concentration dependence of radius of gyration (R-g) of sodium poly(styrene sulfonate)s (NaPSS) in aqueous solutions without added salt was studied by small-angle neutron scattering measurements over a wide range of concentrat ion. The R-g values are always higher than those of corresponding nonionic polymer, polystyrene, and the concentration (C) dependence of R-g of NaPSS in the semidilute region (C < 0.3 x 10(3) kg/m(3)) can be well expressed by the scaling relation (R-g proportional to C-1/4), while R-g values in the concentrated region are almost constant at the value almost equal to that a t Theta condition. The crossover concentration from the semidilute to conce ntrated regions was also consistent with our previous studies of viscoelast ic properties of polyelectrolyte solutions without added salts.