Compositional ripening of particle- and surfactant-stabilised emulsions: a comparison

Abstract

When β-ionone-in-water emulsions are mixed with squalane-in-water emulsions, the slightly water-soluble, mobile β-ionone undergoes mass transfer to the drops of highly water-insoluble, immobile oil squalane. We have investigated this compositional ripening process for emulsions stabilised either by particles or by surfactant molecules. For particle-stabilised emulsions, the swelling of the squalane-containing drops triggers droplet coalescence which causes the final swollen droplet radius to be proportional to the swelling ratio to the power of 1. Surfactant-stabilised emulsions swell without coalescence which causes the final droplet radius to be proportional to the swelling ratio to the power 1/3. Addition of excess, non-adsorbed particles to the particle-stabilised emulsions suppresses the swelling-triggered coalescence and causes a switchover from particle to surfactant behaviour.