Hydrolysis-induced large swelling of polyacrylamide hydrogels

Polyacrylamide hydrogels are widely used and studied. The feature of hydrolysis in polyacrylamide gels is often ignored. After neutral polyacrylamide gels are hydrolyzed under alkaline conditions, they become polyelectrolyte gels and exhibit large swelling capability. In this work, we establish a non-equilibrium thermodynamic theory to describe large deformation of polyacrylamide gels in the context of hydrolysis. In particular, our theory accounts for the auto-retardation of the reaction. A thermodynamic consistent reaction kinetics is proposed. The theoretical model is validated by comparing with experiments. Our work might be important for the utilization of polyacrylamide gels.