Oil‐Soluble Polymer Brush Grafted Nanoparticles as Effective Lubricant Additives for Friction and Wear Reduction

Abstract

The development of high performance lubricants has been driven by increasingly growing industrial demands and environmental concerns.H erein, we demonstrate oilsoluble polymer brush-grafted inorganic nanoparticles (hairy NPs) as highly effective lubricant additives for friction and wear reduction. As eries of oil-miscible poly(lauryl methacrylate) brush-grafted silica and titania NPs were synthesized by surface-initiated atom transfer radical polymerization. These hairy NPs showed exceptional stability in poly(alphaolefin) (PAO)base oil;nochange in transparency was observed after being kept at À20, 22, and 100 8 8Cf or ! 55 days.H igh-contact stress ball-on-flat reciprocating sliding tribological tests at 100 8 8Cshowed that addition of 1wt% of hairy NPs into PAO led to significant reductions in coefficient of friction (up to % 40 %) and wear volume (up to % 90 %). The excellent lubricating properties of hairy NPs were further elucidated by the characterization of the tribofilm formed on the flat. These hairy NPs represent anew type of lubricating oil additives with high efficiency in friction and wear reduction.

Competitive Adsorption of Ionic Liquids Versus Friction Modifier and Anti-Wear Additive at Solid/Lubricant Interface—Speciation with Vibrational Sum Frequency Generation Spectroscopy

“…It could, however, be attributed to symmetric methylene Fermi resonance of N-CH 2 -CH 2 -N (see Figure 1) as in the case of 1,3-propanediol (HOCH 2 CH 2 CH 2 OH) [29]. Although we cannot rule out a small fraction of PAO4 is co-adsorbed at the solid surface, the dominance of PIBSI at the solid/(PAO4 + PIBSI) interface explains the improved tribological performance of this mixture compared to the base oil only case [10,50].…”

“…Beneficial effects [10,50] PAO4 Reduction of friction by~30% and wear by >70% [6]. The SFG results show that this improved performance must be related to the properties of the tribofilm formed during the tribological test, rather than the initial surface film before tribo-test.…”

“…Beneficial effects [50] PAO4 + PIBSI PIBSI preferential adsorbs to the silica/liquid interface and seems to lie relatively flat at the surface.…”

Brushing up functional materials

“…When grafting oil-soluble polymer brushes onto the surface of nanoparticles, it is highly possible to synthesize excellent lubrication additives for use in oil. For example, Qu et al 112 reported the preparation of one kind of novel oil-soluble hairy nanoparticles (NPs) as highly effective lubricant additives. The as-prepared hairy NPs exhibited exceptional long-term stability in PAO and demonstrated good lubrication properties.…”

Bioinspired oil‐soluble polymers based on catecholamine chemistry for reduced friction

“…[13][14][15] Zhao et al modified inorganic nanoparticles by oil-soluble polymer and reported highly effective lubrication performance for friction and wear reduction. [16][17][18] Additionally, the research performed by Cheng et al showed that the adding of MoS 2 nanosheets modified by oleic diethanolamide borate to the base oil greatly reduced the coefficient of friction (COF) by about 27.9%. 19 In recent years, different "grafting from" methods have been used to successfully graft the polymers to a variety of substrates, such as ring-opening polymerization, atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization, and photopolymerization.…”