Abstract
Extensive efforts have been made to pursue a low-friction state with promising applications in many fields, such as mechanical and biomedical engineering. Among which, the load capacity of the low-friction state has been considered to be crucial for industrial applications. Here, we report a low friction under ultrahigh contact pressure by building a novel self-assembled fluorinated azobenzene layer on an atomically smooth highly-oriented pyrolytic graphite (HOPG) surface. Sliding friction coefficients could be as low as 0.0005 or even lower under a contact pressure of up to 4 GPa. It demonstrates that the low friction under ultrahigh contact pressure is attributed to molecular fluorination. The fluorination leads to effective and robust lubrication between the tip and the self-assembled layer and enhances tighter rigidity which can reduce the stress concentration in the substrate, which was verified by density functional theory (DFT) and molecular dynamics (MD) simulation. This work provides a new approach to avoid the failure of ultralow friction coefficient under relatively high contact pressure, which has promising potential application value in the future.
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The authors would like to acknowledge the support of the National Natural Science Foundation of China (51922058).
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The authors have no competing interests to declare that are relevant to the content of this article. The author Yu TIAN is the Editorial Board Member of this journal. The author Jianbin LUO is the Editor-in-Chief of this journal.
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Dandan XUE. She is a Ph.D. candidate in the State Key Laboratory of Tribology in Advanced Equipment at Tsinghua University. Her current research interests include tribological behavior and mechanism of functionalized organic molecules.
Liran MA. She received her B.S. degree from Tsinghua University in 2005, and received her Ph.D. degree from Tsinghua University in 2010. Following a postdoctoral period at the Weizmann Institute of Science in Israel, she is now working as an associate professor in the State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University. Her interests in tribology have ranged from aqueous lubrication and hydration lubrication to the liquid/solid interface properties. She has published over 50 papers. Her honors include the Hinwin Doctoral Dissertation Award (2011), the Maple Leaf Award for Outstanding Young Tribologists (2015), and Chang Jiang Scholars Program-Young Professor Award (2015).
Yu TIAN. He is a professor and director of the State Key Laboratory of Tribology at Tsinghua University of China. He gained his B.S. and Ph.D. degrees in mechanical engineering at Tsinghua University in 1998 and 2002, respectively. Subsequently, he joined the State Key Laboratory of Tribology in Advanced Equipment. He was a postdoc at the University of California, Santa Barbara with professor Jacob ISRAELACHVILI from 2005 to 2007. His research interest is the science and technology at the interface of physics, materials, engineering, and biology to understand the physical laws of adhesion, friction, and rheology to implement technological inventions to benefit the society. He has published over 150 peer-reviewed journal papers. He has received the Youth Science and Technology Award of China (2016), the Yangtze River Scholars Distinguished Professor (2015–2019), the National Natural Science Foundation for Distinguished Young Scientists of China (2014), the Wen Shizhu-Maple Award-Young Scholar Award (2012), the Young Scholar Achievement Award of the Society of Mechanical Engineering of China (2011), Outstanding Young Scholar Award of the Chinese Tribology Institute (2009), and the National Excellent Doctoral Dissertation of China (2004).
Ming MA. He received his Ph.D. degree in engineering mechanics from Tsinghua University, China, in 2011. He joined the State Key Laboratory of Tribology in Advanced Equipment at Tsinghua University since 2016. His current position is an associate professor. His research areas cover nano-tribology, nanofluidics, superlubricity, and diffusion on surfaces or under confinement.
Qingdao ZENG. He is a professor at the National Center for Nanoscience and Technology, China. He received his Ph.D. degree in inorganic chemistry from Nanjing University, China, in 1997. After this, he worked as a postdoctoral researcher (1997–2000) and an associate professor (2000–2007) at the Institute of Chemistry, Chinese Academy of Sciences, China. He is the author or coauthor of more than 300 original papers in peer reviewed international journals, including J. Am. Chem. Soc., Angew. Chem., Int. Ed., Nano Lett., and ACS Nano, etc. His current research interest focuses on the construction of molecular nanostructures and the fabrication of nanostructures based on organic molecules.
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Xue, D., Xu, Z., Guo, L. et al. Low friction under ultrahigh contact pressure enabled by self-assembled fluorinated azobenzene layers. Friction 12, 1434–1448 (2024). https://doi.org/10.1007/s40544-023-0782-2
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DOI: https://doi.org/10.1007/s40544-023-0782-2