抄録
We have systematically studied the surface sliding friction of hydrogels, and various unique features in gel friction have been discovered. The frictional force and its dependencies on the load are quite different depending on the chemical structures of the gels, surface properties of the opposing substrates, and the measurement condition, which are completely different from those of solids. Most importantly, the friction coefficient of gels exhibits a value as low as 0.001, which cannot be obtained from the friction between two solid materials.
Recently, we developed a general method to synthesize hydrogels with extremely low friction by introducing linear polymer brush on the surface of gels. Then, the frictional coefficient became μ=10-4.
However, conventional gels are mechanically too weak to be used as loading bearing materials. We recently developed anomalously strong gels by introducing a double network structure of the gel. These high strength hydrogels, containing 90 % water, sustain a compressive pressure as high as decades of MPa and show a high wear resistance due to their low friction. These gels might open new era of soft and wet materials for substituting articular cartilage and other tissues.
