(551d) Emulsions Stabilized by Carbon Nanotube/Silica Nanohybrids

Particle-stabilized emulsions can be prepared by using SWNT-silica nanohybrids. The as-prepared SWNT-silica particles generate water-in-oil emulsions, regardless of water/oil volume ratio. Multi-emulsion structure can also be observed occasionally for some big emulsion drops. The emulsion volume fraction and drop size were found to increase with water/oil ratio due to a higher amount of water retained in the emulsion droplets and changes in the viscosity of the continuous phases. However, beyond a certain water/oil ratio, the emulsion fraction rapidly decreases. This point of collapse is a strong function of the amount of SWNT-silica particles in the system. The emulsions are remarkably stable against coalescence and sedimentation, and can be easily separated by filtration or centrifugation. Particle concentration was found to affect adversely the emulsion drop sizes. Oxidation of the nanohybrids by nitric acid can effectively modify the particle surfaces and change the resulting emulsion properties.