Pickering emulsions stabilized by amphiphile covered clays

It is shown that all water soluble amphiphilic compounds like surfactants, polymers, block copolymers and proteins bind strongly to clay particles in water. On saturation, the clays bind up to the multifold weight of the additives of their own weight. Prior to saturation some amphiphilic compounds form precipitates with the clays while others do not. The soluble clay-amphiphile complexes do not lower the surface tension of water even though these particles must obviously be hydrophobic. It is concluded from these results that the clays alone are already hydrophobic particles. Solutions or precipitates of these amphiphile covered clay particles are ideal systems for the formation of stable Pickering emulsions. Depending on the used type and amount of amphiphile, the corresponding Pickering emulsions can have either viscous or gel-like properties with large storage moduli. For some combinations both the water and the oil can be removed from the emulsions without collapse of the three dimensional network of the films. (C) 2011 Elsevier B.V. All rights reserved.