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Professor Seong H. Kim | Research

• Vapor-phase lubrication
• Super-lubricious diamond-like carbon coatings

• Self-healing boundary lubrication films
• Interfacial water

• Bottom-down nanomanufacturing

• Superhydrophobic coatings via atmospheric plasma process

• Noncontact surface topography and charge imaging in water

• Cellulose in plant cells and ligonocellulosic biomass
• Biocatalytic nanofibers

3. Self-healing boundary lubrication films

There is a need to develop efficient boundary lubrication films that can work without the replenishment from the vapor phase and be incorporated into the forthcoming MEMS technology. A new bound and mobile boundary lubricant, cationic polymer lubricant (CPL),^∗ was synthesized for the protection of SiO2 and Si which are base materials for many MEMS devices. CPL forms an ionically bound layer and a mobile multilayer. The multilayer portion can easily flow into a region where CPL is worn off, leading to self-healing behavior. We test the lubrication and self-healing viability of CPL at nanoscale as well as macroscale.

In the macro-scale, the effects of ionic content, environmental condition, and advantage of the bound layer on self-healing demonstrates wear resistance and self-healing capability. CPL also mitigates the detrimental effects of humidity on the wear of SiO₂. In the nano-scale, the results from disjoining pressure and viscosity measurements give insight into the lateral spreading of the mobile layer. The multilayer spreading rates were estimated to be ^∼10^-11 m²/s.

Mobile component of CPL multilayer after scratching the center with an AFM probe at very high contact pressures ^∼5 Gpa. Instead of removing the CPL from the silicon, the CPL multilayer spread around the contacted region.

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