High-Performance Heterocyclic Friction Modifiers for Boundary Lubrication
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The demand for increased energy efficiency continuously drives the development of new lubricants. Here we report the design and synthesis of hexahydrotriazine, triazine, and cyclen derivatives as friction modifiers (FMs) for enhanced fuel economy. This series of sulfur- and phosphorus-free oil-soluble heterocyclic ring-based molecules exhibits differing thermal and chemical stability depending on the degree of aromatization and number of linking spacers within the central heterocyclic ring. Thermally stable triazine and cyclen FMs significantly increase friction performance in the boundary lubrication regime. Cyclens in particular reduce friction by up to 70% over a wide temperature range. Detailed experimental investigations of the newly synthesized FMs at elevated temperatures demonstrate their favorable tribological performance under four operating conditions: variable-temperature sliding, linear speed ramping, reciprocating sliding, and rolling–sliding contact. These latest experimental findings suggest the potential of the application of “designer” heterocyclic FMs for reducing frictional loss in motor vehicles.
KeywordsLubricant additive Friction modifier Boundary lubrication Heterocyclic
The authors gratefully acknowledge financial support from the US Department of Energy under contract DE-EE0006449. Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. The NMR instrumentation at IMSERC was supported by the National Science Foundation under CHE-9871268, and GC–MS instrumentation was supported by a donation from Pfizer. M. Desanker was supported by the Department of Defense (DoD) through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program. We thank AkzoNobel for generously providing Armeen T® to us. We would also like to thank Mr. L. Kangmeng and R. Xu for helping in disk preparation, and Ms. X. Cheng for the assistance with rolling–sliding friction data collection.
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Conflict of interest
The authors declare the following competing financial interest(s): A patent application related to this work has been filed (US Patent Application PCT/US2016/031868).
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