One-Step Preparation of Tough and Self-Healing Polyion Complex Hydrogels with Tunable Swelling Behaviors.

Polyion complex (PIC) hydrogels formed by charge attraction of opposite charged polymers have received unique research interest. Their conventional preparation method, with a large amount of residual salt after polymerization, requires a long-term dialysis treatment to remove the salt and toughen the gel. Here, a promising strategy for the one-step preparation of tough PIC hydrogels without dialysis after polymerization is provided. Bicarbonate and proton ions are selected as the counter ions of the cationic monomer and anionic polymers, respectively. By a CO -generating reaction between the counter ions, the residual salt is removed before polymerization, and thus, a PIC hydrogel with tough mechanical performance can be obtained instantly without dialysis. Due to the absence of dialysis, the tough hydrogel can be formed with a wide range of ratios for the oppositely charged polymer with distinct swelling behaviors from non-swelling to super-swelling. This tunable swelling behavior shows the possibility for shape-morphing systems from this one-step method.