Wettability and friction of CF3-terminated monolayer films on gold

Studies of the wettability and friction of self-assembled monolayers (SAMs) generated from the terminally fluorinated alkanethiols (CF3(CH2)(n)SH, n = 9-15) on gold are reported. These data were compared to those of SAMs gene rated from the non-fluorinated analogs (CH3(CH2)(n)SH, n = 9-15). The CF3-t erminated SAMs were less wettable by hexadecane and methylene iodide, but s urprisingly more wettable by water and glycerol than were the CH3-terminate d SAMs. Measurements of friction by atomic force microscopy (AFM) revealed an approximate threefold increase in friction on the CF3-terminated films c ompared to the CH3-terminated films. A new model for the frictional respons e of fluorinated SAMs is proposed. (C) 1999 Elsevier Science Ltd.