Impact of specific ion effects and electrostatic interactions on a polyelectrolyte-polyampholyte complex

Abstract

A complex overlay of interactions governs the conformations of polymers in solution. Among them, electrostatic interactions are the dominating factor for governing the dynamics of charged macromolecules. Salt ions further impact the conformations by inducing screening of the electrostatic interactions of the polymers. Polyelectrolytes and polyampholytes are two majorly used charged polymers for engineering hydrogels. These polymers form a complex when added together in a solution. This article emphasises the effect of salts on the polyelectrolyte-polyampholyte complex. The interactions have been analysed through the viscosity and diffusivity measurements. The in-depth analysis of the specific ion effect along with the viscous effect induced by the polymer has been carried out. It was concluded that the viscous effect tends to reverse the impact of salts on the electrostatic-dominated conformations of the polymers. The ‘Shear Dependent Generalised Intrinsic Viscosity’ (SDGIV) have been used to gain insights into the interactions between the polymers. Finally, the scaling of the viscosity with respect to the polymer concentration and the impact of the salts on the same has also been studied. It is concluded that the viscous effect of the polymers should also be considered for analysing the specific ion effects of the salts on the charged polymers. Graphical Abstract