Influence of particle hydrophobicity on particle-assisted wetting.
The surface properties of silica particles significantly influence their efficiency in particle-assisted wetting. A series of small particles of controlled surface hydrophobicity was mixed with a nonvolatile oil. These mixtures were applied onto a water surface; the structures formed were subsequently solidified by photopolymerization and observed using scanning electron microscopy. For the most hydrophilic particles, only lenses of pure oil formed, with the particles being submerged into the aqueous phase. The most hydrophobic particles help to form patches of stable homogeneous mixed layers composed of oil and particles. In these cases the particles adhere to the air-oil as well as to the oil-water interfaces. For particles with intermediate hydrophobicity, lenses and patches of mixed layers were observed. These three different observations verify that the hydrophobicity of the particle surface determines the wetting behavior of the oil at the water surface.
Ding
Ailin
A
Organic & Macromolecular Chemistry and Material Science & Catalysis, University of Ulm, 89081 Ulm, Germany.
Binks
Bernard P
BP
Goedel
Werner A
WA