Anomalous enhanced water diffusion in polysaccharide interpenetrating hydrogels

Water structure and dynamics are investigated by 1H NMR in a polysaccharide interpenetrating polymer network (IPN) based on calcium alginate and methacrylated hyaluronic acid. The effects of two solvents, water and a saline NaCl solution, on the transport properties of water and on the polymer structure are analyzed. Anomalous diffusion behavior of water in the different samples is investigated and correlated to the polymer structure. Up to three water fractions are detected in the IPN samples having different hydrogen bond network structure and diffusion properties. This work highlights how the aggregation of hydrophobic domains in amphiphilic hydrogels influences the transport properties of solvent water. In addition, the results emphasize the effect of charged ions, used to improve hydrogel biocompatibility, on the polymer network structure and of polymer interpenetration mechanisms.