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.