Abstract
We examine the frictional properties of zwitterionic surfaces and explore whether chaotropic or kosmotropic charged groups are preferred to achieve lower friction. Self-assembled monolayers of carboxybetaine (CB-SAMs) and sulfurbetaine (SB-SAMs) are used as model surfaces as they contain the same positively charged group, but different negatively charged ones. The negatively charged groups are kosmotropic carboxylates in the CB-SAM surfaces and chaotropic sulfonate groups in the SB-SAM surfaces, respectively. The results show that the friction of the SB-SAM surfaces is even lower than that of the CB-SAM surfaces although both surfaces have low friction. This suggests that chaotropic charged groups are better in reducing friction than kosmotropic groups. The lower friction of the SB-SAM surfaces over the CB-SAM can be explained by the higher mobility of water near the SB-SAM surfaces, as shown in the survival autocorrelation function and the dipole autocorrelation function of hydration water molecules.
Original language | English |
---|---|
Article number | 154702 |
Journal | Journal of Chemical Physics |
Volume | 135 |
Issue number | 15 |
DOIs | |
State | Published - Oct 21 2011 |
Bibliographical note
Funding Information:We would like to thank the National Science Foundation (CMMI 0758358) and the American Chemical Society, Petroleum Research Funds (ACS PRF #48096-AC7) for financial support.
ASJC Scopus subject areas
- Physics and Astronomy (all)
- Physical and Theoretical Chemistry