Infrared-light-driven self-healing MoS2/polyvinyl alcohol hydrogel with simultaneous enhancement of strength and ductility

Self-healing hydrogels exhibit special self-healing or self-recovery function like human skin after injuring, thereafter, draw lots of attention in biomedical applications. However, self-healing hydrogels with strong mechanical and rapid self-healing properties are not fully realized. MoS2/polyvinyl alcohol (PVA) hydrogels are developed to achieve rapid self-healing function by utilizing the excellent photothermal conversion effect of MoS2 under near-infrared (NIR) light. Effects of microstructure and content of MoS2 on self-healing and mechanical properties of MoS2/PVA hydrogels are investigated, including flower-like MoS2 spheres by bottom-up hydrothermal reaction and MoS2 sheets by liquid-phase stripping method. The MoS2/PVA hydrogels embodied with the two types of MoS2 were produced by simple freezing/thawing method, and exhibited rapid self-healing function, together with simultaneous enhancement of strength and ductility. The MoS2/PVA hydrogel modified by flower-like MoS2 spheres with a content of 0.5 wt% presents a significant self-healing function with a healing efficiency up to 90.0% within 5 min, and an enhancement of tensile strength of 9.1 MPa (190% to blank PVA) and a ductility of 162.5% (290% to blank PVA). Furthermore, the MoS2/PVA gel with flower-like MoS2 spheres into the PVA networks produces a significant enhancement of fracture strength (58.4 MPa) after fully curing, characterized by an increases of 612% compared with the pure PVA. The photo-induced self-healing and strengthening effects of the MoS2/PVA hydrogels are discussed.