ISOLATED POLYMER-CHAINS VIA MIXED SELF-ASSEMBLED MONOLAYERS - MORPHOLOGY AND FRICTION STUDIED BY SCANNING FORCE MICROSCOPY

In this paper, we describe a system of mixed self-assembled monolayers of alkanethiols and thiol-terminated polystyrene (PS-SH) chemisorbed on a gold surface from mixed toluene solutions. Topography and frictio n images were obtained with a scanning force microscope (SFM) under ba d-solvent conditions. We observed randomly distributed single polystyr ene coils. We found that the polymer grafting density increases when t he molar ratio of polymer to alkanethiol in solution increases. The lo cal friction coefficient on a collapsed polystyrene chain was found to be about 0.3, a value that compares with a macroscopic one of 0.515. X-ray photoelectron spectroscopy and ellipsometry were employed to ver ify and supplement the SFM measurements.