AVS 47th International Symposium
    Surface Science Thursday Sessions
       Session SS2+NS-ThA

Paper SS2+NS-ThA8
The Effect of C60 on Interfacial Friction and Wetting of Toluene

Thursday, October 5, 2000, 4:20 pm, Room 209

Session: Tribology and Adhesion
Presenter: T.S. Coffey, North Carolina State University
Authors: T.S. Coffey, North Carolina State University
M. Abdelmaksoud, North Carolina State University
J. Krim, North Carolina State University
Correspondent: Click to Email
Experimental investigations of friction, lubrication, and adhesion at nanometer length scales have traditionally been performed using atomic force microscopy (AFM), surface forces apparatus (SFA), or quartz crystal microbalance (QCM) techniques. While collectively these techniques yielded useful information, their results have never been cross-referenced. In order to achieve a cross referencing, we investigated the sliding friction of C60 using AFM, QCM, and macroscopic contact angle measurements. (Recent studies@footnote 1@ suggest that a larger contact angle implies a more slippery interface.) C60 has been previously studied by S.E. Campbell et al. with SFA,@footnote 2@ whereby it was reported that C60 at a toluene/mica interface resulted in a full-slip boundary condition, and C60 was recommended as a possible lubricant. Our contact angle measurements reveal that the contact angle of C60/toluene solutions on mica is greater than the contact angle of toluene alone and therefore support Campbell's result. Using QCM, we have also studied the system toluene/Ag(111) with and without C60 deposited on the silver. These studies indicate that toluene on the C60/silver surface is less slippery than the toluene on the silver alone, and that the contact angle for toluene on C60/silver surface is less than the contact angle for the toluene on the silver. This indicates that C60 is not a good lubricant for a silver surface. We believe that this seeming contradiction with Campbell's result is due to the manner in which the C60 is bound to the mica surface vs. the silver surface. We complete our cross referencing of C60/toluene solutions on these substrates by employing AFM. @footnote 3@ @FootnoteText@ @footnote 1@ J.L. Barrat and L. Bocquet, Physical Review Letters, vol. 82, p. 4671 (1999). @footnote 2@ S.E. Campbell, G. Luengo, V.I. Srdanov, F. Wudl, and J.I. Israelachvili, Nature, vol. 382, p. 520 (1996). @footnote 3@ This work is supported by NSF, AFOSR, and a GAANN fellowship.