Fabrication of MXene@Fe₃O₄@PNA composite with photothermal effect as water-based lubricant additive

Improving the tribological performance of water via designing nanomaterials as lubricant additive has garnered mounting interest. In this work, the poly-(N-isopropylacrylamide) microgel is grafted onto Fe₃O₄ nanoparticles surface (Fe₃O₄@PNA) via free radical polymerization. Then, the Fe₃O₄@PNA can self-anchored on the MXene nanosheets via hydrogen bonding interaction to obtain MXene@Fe₃O₄@PNA composite. The as-prepared MXene@Fe₃O₄@PNA can effectively reduce friction and wear when used as a water-based lubricant additive. Compared with pure water, the average coefficient of friction (COF) and wear volume decrease by 61% and 78.7%, respectively. The lubrication mechanism was analyzed by focused ion beam technique-TEM (FIB-TEM) and X-ray photoelectron spectroscopy (XPS). The outstanding tribological performance of MXene@Fe₃O₄@PNA is attributed to the synergistic lubrication effect of MXene and Fe₃O₄@PNA. Interlayer shear of MXene and spherical Fe₃O₄@PNA can make MXene@Fe₃O₄@PNA play a full role of sliding friction and rolling friction mechanism, which can induce tribo-chemical reactions to form a protective film on the contact area of the friction pair. In addition, the hydrophilic groups of the MXene@Fe₃O₄@PNA can adsorb a large number of water molecules and form a hydration layer, reducing the agglomeration of nanosheets and acting as a boundary lubrication film. Moreover, the as-prepared MXene@Fe₃O₄@PNA exhibit excellent photothermal conversion performance in both underwater environment and dry state. Based on this characteristic, infrared light can be collected efficiently and stored quickly. Then, convert and utilize it. Therefore, the multifunctional MXene@Fe₃O₄@PNA has a broad application prospect as a water-based intelligent lubrication additive.