Abstract:

A review, with 38 refs. Double emulsions are emulsion-within-emulsion systems with promising applications. Attempts were made to find new amphiphiles to improve their thermodn. stability and to control the release of active matter or markers from double emulsions. The efforts to study the mechanisms of stabilization and release of water-sol. markers from W/O/W double emulsions are summarized, and the achievements in designing an ultimate synthetic graft-comb copolymeric amphiphile for the internal water-oil interface (the W/O emulsion) as well as for the external oil-water interface (the O/W emulsion) are presented. The amphiphilic polymers allow formation of small multicompartment emulsion droplets of W/O/W that are shear (homogenization) and mech. (centrifugation) resistant. The interface is covered with thick emulsifier layers that impart long-term stability. Addn. of controlled amts. of monomeric emulsifiers (Spans) will form reverse micelles in the oil phase, which are capable of transporting the markers via a diffusion-controlled mechanism from the inner to the outer interface. The tailor-made polymers are an excellent soln. to the 2 key problems that, so far, have prevented the use of double emulsions in certain industrial applications: stability and release. Agricultural formulations, based on stabilization by these polymers, have shown considerable advantages over other common techniques of encapsulating or entrapping active matter. [on SciFinder(R)]