A Rheological and Small-Angle Neutron Scattering Study of the Structure of Gelatin/Polyelectrolyte Complexes under Shear

Abstract

The small-angle neutron scattering and rheology of gelatin/polyanion complexes have been studied as a function of shear rate and ionic strength. It was found that the addition of very small amounts of sodium poly(styrene sulfonate) caused a massive increase in the viscosity of gelatin solutions through the formation of a complex between the two net negatively charged polymers. The scattering data showed a maximum in intensity at a specific value of the momentum transfer, reminiscent of the pattern produced by more concentrated pure polyelectrolyte solutions. At high shear rates the complex systems displayed anisotropic behavior: the scattering intensity at the peak was suppressed parallel to the direction of flow, indicating a change in the structure of the complex, but remained approximately constant perpendicular to the flow.