Abstract
The role of various nonionic surfactants on the adhesive force between a mica plate and a SiO2-surface in moist cyclohexane are investigated using an atomic force microscope (AFM). It is found that the adhesive force decreases with increasing concentration of surfactants and also with the value of Hydrophile-Lipophile Balance (HLB), and that the hydrophilic surfactant with the highest HLB, polyoxyethylene dodecylether (C12E9), has nearly the same ability in the reduction of adhesion as the ionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT). However, it is estimated that different mechanisms are involved for these surfactants; in the case of AOT, water is removed from the surface because water is dissolved as micelles with AOT, but, in the case of C12E9, water is not only solubilized but also captured by C12E9 with the long hydrophilic chain on the surface so that sufficient water cannot be supplied for bridging.
