Non-aqueous, surfactant-free antifoam emulsions: Properties and triggered release

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Abstract

Processing convenience and formulation flexibility frequently require the delivery of the silicone oils as emulsions. The shelf life of the latter is achieved kinetically, in the most cases via the addition of surfactants. On the other hand, surfactants are the subject of increasing scrutiny with regard to their environmental impact. The goal of this study is to formulate silicone oils in surfactant-free emulsions and to demonstrate the controlled release of the active silicone material.

A non-aqueous silicone emulsion comprising of a continuous phase of a polar organic liquid, having droplets of silicone antifoam compound dispersed therein, have been developed. These systems are stabilised by (fractal) waxy particles which play a dual role. They act as Pickering stabilisers and in the same time they form an elastic network in the continuous phase, providing a creaming stability of more than a year. A triggered release of the (antifoam) silicone active can be achieved via heating above the melting temperature of the waxy particles. This is demonstrated by the fact that no antifoam activity has been observed at temperatures below ca. 60°C, while at temperature of above 65–70°C a strong antifoam effect has been obtained.

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