PHASE-SEPARATION OF BINARY-MIXTURES OF POLAR LIQUIDS CLOSE TO SOLID-SURFACES

The sticking forces of fused quartz filaments have been measured in a binary mixture of polar liquids, water and butanol. The values of the sticking force for hydrophilic filaments in a solution of water in butanol agree with the Laplace equation and are related to the formation of a water annulus in the contact zone. The sticking force of methylated silica is due to hydrophobic interactions or the formation of a gas-vapor bubble. In this case, no capillary forces from any liquid annulus were detected. The results agree with experiments on the coagulation of silica sols in water-butanol solutions.