Photothermally responsive and durable polydopamine-modified MXene-PNIPAM hydrogels for smart friction regulation

In this study, a polydopamine (PDA)-modified MXene-PNIPAM (pMP) hydrogel is prepared using a soap-free emulsion polymerization method, which shows enhanced anti-oxidative, photo-thermal, and tribological properties. The introduction of PDA not only inhibits the oxidation of MXene but also enhances the photo-thermal conversion efficiency of the hydrogel. Even after 50 days, it can still maintain good photo-thermal conversion performance. Moreover, compared with PNIPAM hydrogel, the friction coefficient (COF) and wear volume of pMP hydrogel as lubricant were reduced by 33% and 85%, respectively. Interestingly, the control of COF with excellent reversibility and durability is achieved using pMP hydrogel modulated by near-infrared light. The pMP composite hydrogel exhibits promising prospects in the fields of intelligent robots and biomedical devices.