Effect of surface grafted hydrophilic polymer chains to reduce the friction character

Lubricity is one of the most important properties in the field of biomaterial, such as artificial joints, bearings of blood pumps, the surface of catheters. Recently, the effects of graft polymerization of biocompatible phospholipid polymer 2-methacryloyloxyethyl phosphorylcholine (MPC) onto the surface of artificial joints are investigated, and it is found that the MPC grafting markedly decreased the friction and the amount of wear. But this lubrication mechanism have not been made clear yet. The purpose of this study is preparation of the lubricated surface and solution of the mechanism of lubricity by focusing on polymer-grafted layers. We grafted MPC, polyetheleneglycol-monomethacrylate (PEGMA), and acryl acid (AA) onto the surface of polypropylene (PP) by photo-induced graft polymerization and analyzed the surfaces of the polymer-grafted PP. As a result, MPC-grafted PP surface is hydrophilic and has pretty good lubricity in water. It was considered that MPC-grafted surface made fluid layer and became the state of fluid lubricity, so MPC-grafted surface had lubricity in water.