AN INVESTIGATION ON THE MUTUAL-PHOBICITY BETWEEN FLUOROCARBON AND HYDROCARBON SURFACTANTS BY ATOMIC-FORCE MICROSCOPY

Atomic force microscopy was used to investigate the mixed monolayer of FC- and HC-amphiphiles. Clear topographic images showing domain struc ture of the mixed monolayer and the data of the domain size have been provided. It is revealed that in the mixed monolayer the sodium octade canesulfonate molecules construct the hexagonal domain dispersing in t he continuous two-dimensional phase of perfluorononanoic acid. These r esults strongly support that, due to the mutual-phobicity between fluo rocarbon chain and hydrocarbon chain, there exists phase separation in the mixed monolayer of fluorocarbon and hydrocarbon amphiphiles, albe it the pi-A curves would obey the simple additive rule. (C) 1997 Acade mic Press