Synthesis of Surface-Responsive Composite Particles by Dehydration of Water-in-Oil Emulsions.

Organic composite particles were prepared by first emulsifying an aqueous sodium carboxymethyl cellulose (CMC) solution in a nonaqueous ethylcellulose (EC) solution, followed by dehydrating emulsified water droplets. CMC and EC are both biodegradable nontoxic materials, but have contrasting properties. CMC is a charged water-soluble polymer, while EC is an uncharged interfacially active water-insoluble polymer. The simple preparative method does not consume unnecessary chemical reagents and produces no waste material. The composite particles prepared by dehydrating emulsion droplets are readily dispersed in organic media due to its biwettable surface terminated with interfacially active EC molecules, which allows composite particles to preferentially adsorb at the oil-water droplet interface. The surface of composite particles, furthermore, is water-permeable, which allows water to be absorbed from emulsified droplets. The size, composition, and structure of the synthesized composite particles are ideally suited for absorption of stabilized water droplets from oil-continuous emulsions. The use of the composite absorbent particles, described herein, presents another viable strategy for dewatering water-in-oil emulsions.