Enhancing the lubricity and wear resistance of shape-memory-polymer via titanium carbide-based MAX and MXene

Sliding surfaces not only consume an exceptional amount of energy to overcome friction but also cause premature failure of mechanical systems due to wear, leading them to be frequently replaced. Friction and wear are, therefore, major concerns from the viewpoints of energy consumption, cost, and the environment. Here we report for the first time the development of tribologically resilient and self-healing smart composites comprising shapememory polyurethane (SMPU) as the model polymer matrix and titanium carbide-based MAX and MXene materials as fillers. The ball-on-disk tribological tests and 3D optical surface profilometry tests are performed to examine the coefficient of friction and wear. The introduction of layered MAX and MXene phase materials exceptionally reduces the friction of SMPU by 2-3 times and reduces its wear rate by 2-3 orders of magnitude, even at low filler concentrations of 0.25 wt%. In-depth wear track analysis, using Raman spectroscopy and EDAX elemental mapping, reveals the presence of MAX and MXene at the wear track, in addition to tribochemically formed TiO2, which contributes to the SMPU's lubricity and wear resistance. Furthermore, the developed materials reveal damage healing capability, which is not hindered by the reinforcement of MAX and MXene as well. The results suggest that by using these composites, not only the friction and wear but also the frequent replacement of sliding components can be minimized, which is crucial for cost-saving and environmentally sustainable technologies.