A dual-crosslinked zwitterionic hydrogel with load-bearing capacity and ultra-low friction coefficient

Due to similar properties to that of cartilage, hydrogels are considered as promising candidates for cartilage repair. However, it is still a challenge to synthesize hydrogel combining high strength and low friction like natural cartilage. In this work, we synthesized a dual-crosslinked zwitterionic P(AAm-co-AAc-co-SBMA)/Fe 3+ hydrogel, in which a zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)(SBMA) was used to improve the hydrophilicity of the polymer chain. The results showed that the hydrogel exhibited significantly improved tensile strength (9.9 MPa) and compressive strength (207.6 MPa), which was due to the physical crosslinking points introduced by SBMA. Moreover, the zwitterionic hydrogel achieved an ultra-low friction coefficient (CoF) of 0.04 in water. The results provide a new approach for cartilage repair materials with considerable strength and low friction.