Amino-functionalized Ti₃C₂ and ZIF-8-induced high lubricity, friction robust self-healing polyurethanes as solid lubrication films

Self-healing polyurethane (SPU) has important applications in areas such as protective coatings, medical devices and solid lubrication. However, improving the lubricating properties of self-healing polyurethanes to reduce their friction and wear is still an important challenge. Herein, an amphoteric SPU is prepared and used as the solid lubrication matrix. NH₂-Ti₃C₂-ZIF-8 is grown on NH₂-Ti₃C₂ in situ to obtain NH₂-Ti₃C₂-ZIF-8 as lubrication additive. The lubrication performance of NH₂-Ti₃C₂-ZIF-8/SPU composites is the best when the NH₂-Ti₃C₂-ZIF-8 content is 1.00 wt%. The coefficient of friction (COF) is only 0.10, and the wear rate is only 1.315×10⁻⁴ mm³/(N·m), which are reduced by 80.4 % and 99.4 % respectively compared with single SPU. By exploring the lubrication mechanism, it is found that NH₂-Ti₃C₂-ZIF-8 participated in producing transfer film during friction, and the excellent lubricity and anti-wear effect of NH₂-Ti₃C₂ and the unique adsorption and rolling effect of ZIF-8 jointly improved the friction performance of the samples. In addition, the composite material can realize rapid healing within 5 min at 75 %RH, 20℃, the self-healing efficiency can reach 84.7 %. Therefore, the SPU containing NH₂-Ti₃C₂-ZIF-8 has potential applications in the field of solid lubricated materials.