Scattering and viscosimetric behaviors of four- and six-arm star polyelectrolyte solutions
Résumé
This paper discusses the scattering and viscosity results of four- and six-arm sodium, cesium, and rubidium polyacrylate (PANa, PACs, PARb) star polyelectrolyte solutions in comparison with their equivalent linear polyelectrolyte chains. The polyelectrolyte effect is highlighted in these systems, and an estimate of the persistence length is deduced from static light scattering and X-ray scattering. Static and dynamic light scattering studies permitted to determine their mass average molar mass (M-w) their radius of gyration < R-g>, their second virial coefficient A(2), their hydrodynamic radius R-H, and their persistence length L-P. The polyelectrolyte "abnormal" behavior was observed in the variation of the reduced Viscosity eta(red) as a function of the polyelectrolyte concentration C-P on linear and star systems (existence of a maximum in eta(red) vs C-P). Additionally to the specific behavior brought by the star architecture, the results also show an important effect due to the type of counterions and the charge parameter on the scattering and the viscometric properties. A systematic comparison between linear and star polyelectrolytes having similar molar mass, counterions, and charge parameter is presented.