Enhanced lubrication by core-shell TiO2 nanoparticles modified with gallic acid ester

Abstract Nanoparticles (NPs) added to oils have been demonstrated to enhance engine lubrication, but sedimentation issues are barriers to their implementation. Here, we engineer TiO2 NPs with polyphenol derivatives (2-octyldodecyl gallate, ODG), not only to improve dispersion stabilities but also to introduce phenol-related tribochemical reactions. To that end, we compare dispersion and lubrication performances of ODG modified TiO2 (ODG@TiO2) NPs with unmodified ones in two base oils, polyalphaolefin and commercial engine oil. Surface analysis results reveal the triboactive role played by ODG in ODG@TiO2 NPs, which helps them to reduce more friction than with non-modified NPs, to generate thicker tribofilms, and to strengthen surface mechanical properties. Thus, we expect further explorations of polyphenol derivatives to improve NPs properties in lubricant applications.