Double-network polyvinyl alcohol composite hydrogel with self-healing and low friction

Polyvinyl alcohol (PVA) hydrogel is considered the most promising candidate for artificial cartilage because of its good lubricity and low permeability. However, the efficacy of single-network PVA hydrogels under variable loads has not yet been determined. In this study, a one-step physical-cross-linking method was used to compose PVA/PEG double-network composite hydrogels. We changed the polyethylene glycol (PEG) content of the composite gel and tested the frictional-wear performance under different loads and speeds. With the mass fraction of PEG at 30 wt.%, the hardness of the PVA/PEG composite gel increased to 167.7% that of pure PVA. Under dry-friction conditions, the average coefficient of friction was approximately 0.14 and the wear rate on the surface of the hydrogel was insignificant. The cross-linking between PVA and PEG greatly enhanced the stability of the composite hydrogel polymer network. The structure of the composite gel was analyzed by a variety of standard methods. The hydrogel has excellent biocompatibility and self-healing ability and is a self-lubricating, self-healing candidate material for articular-cartilage repair.