Swelling equilibria, dynamics, and rheology of charged coacervate gels

We have investigated swelling and dynamic properties of the composite hydrogel composed of anionic poly(acrylamide-r-sodium acrylate) gel matrix and linear polycationic poly(allylamine) hydrochloride. We have quantified the role of added salt concentration on the extent of volume shrinkage and enhancement of shear modulusarising from electrostatic complexation between the guest polymer and the host gel. In tandem, the dynamics of the guest polymer, as monitored using FCS and FRET, exhibits diffusive–subdiffusive–diffusive behavior depending on the time scale. At intermediate time scales, the degree of anomalous diffusion increases as the salt concentration is decreased. Our results show design rules to tune the mechanical properties of composite hydrogels using concentration of added salt.