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Cationic Surfactant Micelles Lubricate Graphitic Surface in Water
Jinjin Li1, Jianfeng Li1, Liang Jiang2
1State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China.
Langmuir : the ACS Journal of Surfaces and Colloids
|August 1, 2019
Summary
Researchers achieved ultra-low friction on graphitic surfaces using water-lubricated cationic surfactant micelles. This novel lubrication strategy significantly reduces friction, even after micellar rupture under pressure.
Area of Science:
- Tribology
- Materials Science
- Surface Chemistry
Background:
- Achieving superlubricity (extremely low friction) on graphitic surfaces in water is challenging compared to dry conditions.
- Existing lubrication methods for graphene and graphite in aqueous environments are often insufficient.
Purpose of the Study:
- To develop a novel strategy for achieving ultra-low friction on graphitic surfaces using water lubrication.
- To investigate the mechanism of friction reduction using self-assembled cationic surfactant micelles.
Main Methods:
- Utilizing self-assembly of cationic surfactant micelles on silica and graphene surfaces under varying contact pressures.
- Measuring friction coefficients at the nanoscale using atomic force microscopy.
- Analyzing the shear plane formation and interface changes before and after micellar rupture.
Main Results:
- A friction coefficient as low as 0.0004 was achieved with uniform surfactant micelles on graphene in water.
- Even after micellar rupture under high pressure, the friction coefficient remained in the superlubricity regime (0.005).
- Friction behavior was attributed to a shift in shear planes from micelle/micelle to surfactant molecules/graphene layers.
Conclusions:
- Cationic surfactant micelles provide an effective lubrication strategy for graphitic surfaces in water.
- The lubrication mechanism is robust, maintaining superlubricity even when micelles rupture.
- This approach offers a new pathway for designing advanced water-based lubrication systems for graphitic materials.
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