Long Range Attraction between Glass Surfaces in Cyclohexane-Ethanol Binary Liquids

Interaction forces between glass surfaces in cyclohexane-ethanol binary mixtures were investigated using colloidal probe atomic force microscopy. An unusually long range attraction was found in the presence of ethanol in the concentration range of 0.1 ∼ 1.4 mol%. At 0.1 mol% ethanol, the attraction appeared at a distance of 35 ± 3 nm and turned into a repulsive force below 3.5 ± 1.5 nm upon compression. A possible explanation accounting for this long range attraction is the bridging of opposed adsorption layers of ethanol on the glass surfaces.