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Updated: Apr 28, 2026

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Effect of molecular orientation angle of imidazolium ring on frictional properties of imidazolium-based ionic liquid
S Watanabe1, M Nakano, K Miyake
1Department of Mechanical Engineering, Tokyo University of Science , 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
Abstract:
Ionic liquids have significant potential as lubricants, and it is known that ionic liquids exhibit characteristic behavior at solid-liquid interfaces. Although it is believed that the structure of ionic liquids at the interface contributes to the tribological properties in the region of boundary-mixed lubrication, this contribution has not been clarified because such analysis is difficult. In this research, we clarify the lubrication mechanism of an imidazolium-based ionic liquid by comparing the results of friction tests with interfacial molecular orientation analysis using sum frequency generation spectroscopy. Consequently, we clarify that the tilt angle of the imidazolium ring affects the friction coefficient of the ionic liquid; that is, the larger tilt angle, the lower the friction coefficient.
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