TY - JOUR
T1 - Position of Carbonyl Group Affects Tribological Performance of Ester Friction Modifiers
AU - Song, Wei
AU - Campen, Sophie
AU - Shiel, Huw
AU - Gattinoni, Chiara
AU - Zhang, Jie
AU - Wong, Janet S S
N1 - Funding Information:
H.S. is supported by the INFUSE Prosperity Partnership (Grant No.: EP/V038044/1). J.Z. is supported by the Shell University Technology Centre (UTC) for Mobility and Lubricants. The authors would like to thank Dr Peter Quayle of University of Manchester for supplying OG and SG, Dr Gwilherm Kerherve of the Advanced Photoelectron Spectroscopy Laboratory, Imperial College London, for his help with XPS, and Dr Sarah Fearn in Department of Materials, Imperial College London, for her help with ToF-SIMS. For the purpose of open access, the author has applied for a Creative Commons Attribution (CC BY) license to any Author Accepted Manuscript version arising.
Publisher Copyright:
© 2024 The Authors. Published by American Chemical Society.
PY - 2024/3/20
Y1 - 2024/3/20
N2 - The tribological properties of lubricants can be effectively improved by the introduction of amphiphilic molecules, whose performance is largely affected by their polar head groups. In this work, the tribological performance in steel-steel contacts of two isomers, glycerol monostearate (GMS) and stearyl glycerate (SG), a glyceride and a glycerate, were investigated as organic friction modifiers (OFM) in hexadecane. SG exhibits a much lower friction coefficient and wear than GMS despite their similar structures. The same applies when comparing the performance of oleyl glycerate (OG) and its isomer, glycerol monooleate (GMO). Surface chemical analysis shows that SG forms a polar, carbon-based, tribofilm of around tens of nanometers thick, while GMS does not. This tribofilm shows low friction and robustness under nanotribology test, which may contribute to its superior performance at the macro-scale. The reason for this tribofilm formation can be due to the stronger adsorption of SG on the steel surface than that of GMS. The tribofilm formation can be stress-activated since lower friction and higher tribofilm coverage can be obtained under high load. This work offers insights into the lubrication mechanism of a novel OFM and provides strategies for OFM design.
AB - The tribological properties of lubricants can be effectively improved by the introduction of amphiphilic molecules, whose performance is largely affected by their polar head groups. In this work, the tribological performance in steel-steel contacts of two isomers, glycerol monostearate (GMS) and stearyl glycerate (SG), a glyceride and a glycerate, were investigated as organic friction modifiers (OFM) in hexadecane. SG exhibits a much lower friction coefficient and wear than GMS despite their similar structures. The same applies when comparing the performance of oleyl glycerate (OG) and its isomer, glycerol monooleate (GMO). Surface chemical analysis shows that SG forms a polar, carbon-based, tribofilm of around tens of nanometers thick, while GMS does not. This tribofilm shows low friction and robustness under nanotribology test, which may contribute to its superior performance at the macro-scale. The reason for this tribofilm formation can be due to the stronger adsorption of SG on the steel surface than that of GMS. The tribofilm formation can be stress-activated since lower friction and higher tribofilm coverage can be obtained under high load. This work offers insights into the lubrication mechanism of a novel OFM and provides strategies for OFM design.
UR - http://www.scopus.com/inward/record.url?scp=85187536257&partnerID=8YFLogxK
U2 - 10.1021/acsami.3c16432
DO - 10.1021/acsami.3c16432
M3 - Article
C2 - 38456401
SN - 1944-8244
VL - 16
SP - 14252
EP - 14262
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 11
ER -