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Seymour BT, Wright RAE, Parrott AC, et al. Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property. ACS Appl Mater Interfaces. 2017;9(29):25038-25048doi: 10.1021/acsami.7b06714.
Seymour, B. T., Wright, R. A. E., Parrott, A. C., Gao, H., Martini, A., Qu, J., Dai, S., & Zhao, B. (2017). Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property. ACS applied materials & interfaces, 9(29), 25038-25048. https://doi.org/10.1021/acsami.7b06714
Seymour, Bryan T, et al. "Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property." ACS applied materials & interfaces vol. 9,29 (2017): 25038-25048. doi: https://doi.org/10.1021/acsami.7b06714
Seymour BT, Wright RAE, Parrott AC, Gao H, Martini A, Qu J, Dai S, Zhao B. Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property. ACS Appl Mater Interfaces. 2017 Jul 26;9(29):25038-25048. doi: 10.1021/acsami.7b06714. Epub 2017 Jul 12. PMID: 28670899.
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ACS Appl Mater Interfaces. 2017 Jul 26;9(29):25038-25048. doi: 10.1021/acsami.7b06714. Epub 2017 Jul 12.

Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property.

ACS applied materials & interfaces

Bryan T Seymour, Roger A E Wright, Alexander C Parrott, Hongyu Gao, Ashlie Martini, Jun Qu, Sheng Dai, Bin Zhao

Affiliations

  1. Department of Chemistry, University of Tennessee , Knoxville, Tennessee 37996, United States.
  2. Department of Mechanical Engineering, University of California , Merced, California 95343, United States.

PMID: 28670899 DOI: 10.1021/acsami.7b06714

Abstract

This article reports on the synthesis of a series of poly(alkyl methacrylate) brush-grafted, 23 nm silica nanoparticles (hairy NPs) and the study of the effect of alkyl pendant length on their use as oil lubricant additives for friction and wear reduction. The hairy NPs were prepared by surface-initiated reversible addition-fragmentation chain transfer polymerization from trithiocarbonate chain transfer agent (CTA)-functionalized silica NPs in the presence of a free CTA. We found that hairy NPs with sufficiently long alkyl pendant groups (containing >8 carbon atoms, such as 12, 13, 16, and 18 in this study) could be readily dispersed in poly(alphaolefin) (PAO), forming clear, homogeneous dispersions, and exhibited excellent stability at low and high temperatures as revealed by visual inspection and dynamic light scattering studies. Whereas poly(n-hexyl methacrylate) hairy NPs cannot be dispersed in PAO under ambient conditions or at 80 °C, interestingly, poly(2-ethylhexyl methacrylate) hairy NPs can be dispersed in PAO at 80 °C but not at room temperature, with a reversible clear-to-cloudy transition observed upon cooling. High-contact-stress ball-on-flat reciprocating sliding tribological tests at 100 °C showed significant reductions in both the coefficient of friction (up to 38%) and wear volume (up to 90% for iron flat) for transparent, homogeneous dispersions of hairy NPs in PAO at a concentration of 1.0 wt % compared with neat PAO. The formation of a load-bearing tribofilm at the rubbing interface was confirmed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.

Keywords: antiwear; colloidal stability; friction reduction; hairy nanoparticles; lubricant additives; oil solubility; surface-initiated RAFT polymerization

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