| AVS 60th International Symposium and Exhibition | |
| Tribology Focus Topic | Tuesday Sessions |
| Session TR+SE-TuM |
| Session: | Low Friction Materials |
| Presenter: | S.P. Pujari, Wageningen University, Netherlands |
| Authors: | S.P. Pujari, Wageningen University, Netherlands H. Zuilhof, Wageningen University, Netherlands |
| Correspondent: | Click to Email |
Micro and Nano Electro Mechanical Systems (MEMS/NEMS) are considered to be an important technology for the development of several products in daily life such as electronics, medical devices, and packaging. Despite the tremendous progress in micro-fabrication, the development of highly robust surfaces, having ultra-low adhesion as well as friction and resistance against wear, is still a challenging subject of accomplishment. To this aim, new fluorine-containing terminal alkynes and alkenes were synthesized and self-assembled onto inorganic substrates ( Si(111), SiC, and CrN) to obtain fluorine containing organic monolayers. The resultant covalently bound organic monolayers have similar surface properties as polytetrafluoroethylene (PTFE), but they are more stable than traditionally coated PTFE.
A combination of spectroscopic (XPS, IR), nanoscopic (AFM), and contact angle measurements shows that these monolayers were ordered and highly hydrophobic. Increasing the amount of fluorine on the alkyne precursor resulted in monolayers with a greatly reduced adhesion to silica probes, as well as an almost 5-fold decrease in the coefficient of friction on the surface. Overall, this yields a friction coefficient that is – to the best of our knowledge – lower than reported for any other thin organic monolayer. In addition, these monolayer-coated Si(111), SiC, and CrN surfaces perform superiorly over uncoated.1,2,3 For instance, at a normal force of ~7 µN, the monolayer-coated samples are still nearly undamaged, while an uncoated Si surface displays already wear marks of 8 nm deep. The remarkable tribological properties make these fluorinated monolayers promising candidates for the development of robust, high–performance MEMS/NEMS systems.
1. Ultralow Adhesion and Friction of Fluoro-Hydro Alkyne-Derived Self-Assembled Monolayers on H-Terminated Si(111) Sidharam P. Pujari, Evan Spruijt, Martien A. Cohen Stuart, Cees J. M. van Rijn, Jos M. J. Paulusse, and Han Zuilhof Langmuir 2012 28 (51), 17690-17700.
2. Covalently Attached Organic Monolayers onto Silicon Carbide from 1-Alkynes: Molecular Structure and Tribological Properties Sidharam P. Pujari, Luc Scheres, Tobias Weidner, Joe E. Baio, Martien A. Cohen Stuart, Cees J. M. van Rijn, and Han Zuilhof Langmuir 2013 29 (12), 4019-4031.
3. Tribology and Stability of Organic Monolayers on CrN: A Comparison between Silane, Phosphonate, Alkene, and Alkyne Chemistries Sidharam P. Pujari, Li Yan, Regeling Remco, and Han Zuilhof Langmuir 2013 Submitted.