Mechanically Strong Hydrogels with Ultra‐Low Frictional Coefficients

High‐strength, low‐frictional‐coefficient gels are produced by adding a third component to a double‐network gel (DN gel), of either a weakly crosslinked network or non‐crosslinked linear chains (to produce, respectively, a triple‐network gel (TN gel) and a DN‐L gel, see Figure). All the gels are highly transparent. The DN‐L gel shows a fracture strength as high as 9 MPa and its frictional coefficient is as low as 10 –5 under an extremely high pressure of the order of sub‐MPa.