Triple-network hydrogels with high strength, low friction and self-healing by chemical-physical crosslinking

Hydrogels are widely used in the field of water lubrication and friction, such as artificial cartilage, because of their good wettability and flexibility. Moreover, compared with single network hydrogel, Triple-network (TN) hydrogel has higher fracture stress. Therefore, the research and preparation of a TN hydrogel with good mechanical properties and friction properties will be of great help to the improvement and application of hydrogel properties.

A chemical-physical crosslinked triple-network (TN) hydrogel was prepared using PVA, PVP and AA as raw materials. By controlling the content of Zn²⁺ in TN hydrogel, conducting tension-compression test and friction test, we studied the effect of Zn²⁺ on the mechanical properties and friction properties of hydrogel.

The results showed that TN hydrogel had the best mechanical properties when the content of Zn²⁺ was 0.4 g. The fracture stress was 1.87 MPa, the strain rate was 175%, and the compressive stress was 3.5 MPa under 80% compressive deformation. At room temperature, TN hydrogel had good self-healing property and could maintain a high mechanical recovery rate, with a maximum recovery rate of 87%. The friction test results manifested that the hydrogel had a low friction coefficient, and the minimum friction coefficient was 0.15. The PVA/PVP/PAA-TN hydrogel prepared by this method has widened the application scope of hydrogel, making it more applicable in the field of high friction coefficient and mechanical properties.