Department of

Chemical Engineering

Designing molecular technology for the 21st century with biology and chemistry


 


Professor Seong H. Kim | Research




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.



Diagram of a mobile component of CPL multilayer after scratching the center with an AFM probe at very high contact pressures ~5 Gpa.

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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