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

Abstract

This paper 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 dispersionsmore » of hairy NPs in PAO at a concentration of 1.0 wt % compared with neat PAO. Finally, the formation of a load-bearing tribofilm at the rubbing interface was confirmed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.« less

Authors:
 [1];  [1];  [1];  [2];  [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [1]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry
  2. Univ. of California, Merced, CA (United States). Dept. of Mechanical Engineering
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  4. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Science Division
Publication Date:
Research Org.:
Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Contributing Org.:
Univ. of California, Merced, CA (United States)
OSTI Identifier:
1376473
Alternate Identifier(s):
OSTI ID: 1430640
Grant/Contract Number:  
AC05-00OR22725; EE0006925
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 29; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; antiwear; colloidal stability; friction reduction; hairy nanoparticles; lubricant additives; oil solubility; surface-initiated RAFT polymerization

Citation Formats

Seymour, Bryan T., Wright, Roger A. E., Parrott, Alexander C., Gao, Hongyu, Martini, Ashlie, Qu, Jun, Dai, Sheng, and Zhao, Bin. Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property. United States: N. p., 2017. Web. doi:10.1021/acsami.7b06714.
Seymour, Bryan T., Wright, Roger A. E., Parrott, Alexander C., Gao, Hongyu, Martini, Ashlie, Qu, Jun, Dai, Sheng, & Zhao, Bin. Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property. United States. https://doi.org/10.1021/acsami.7b06714
Seymour, Bryan T., Wright, Roger A. E., Parrott, Alexander C., Gao, Hongyu, Martini, Ashlie, Qu, Jun, Dai, Sheng, and Zhao, Bin. 2017. "Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property". United States. https://doi.org/10.1021/acsami.7b06714. https://www.osti.gov/servlets/purl/1376473.
@article{osti_1376473,
title = {Poly(alkyl methacrylate) Brush-Grafted Silica Nanoparticles as Oil Lubricant Additives: Effects of Alkyl Pendant Groups on Oil Dispersibility, Stability, and Lubrication Property},
author = {Seymour, Bryan T. and Wright, Roger A. E. and Parrott, Alexander C. and Gao, Hongyu and Martini, Ashlie and Qu, Jun and Dai, Sheng and Zhao, Bin},
abstractNote = {This paper 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. Finally, the formation of a load-bearing tribofilm at the rubbing interface was confirmed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.},
doi = {10.1021/acsami.7b06714},
url = {https://www.osti.gov/biblio/1376473}, journal = {ACS Applied Materials and Interfaces},
issn = {1944-8244},
number = 29,
volume = 9,
place = {United States},
year = {Mon Jul 03 00:00:00 EDT 2017},
month = {Mon Jul 03 00:00:00 EDT 2017}
}

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Dispersion of Nanoparticles in Lubricating Oil: A Critical Review
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Statistical copolymerization of N-vinyl-pyrrolidone and alkyl methacrylates via RAFT: reactivity ratios and thermal analysis
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Frictional performance evaluation of sliding surfaces lubricated by zinc - oxide nano-additives
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Practical use of polymer brushes in sustainable energy applications: interfacial nanoarchitectonics for high-efficiency devices
journal, January 2019