The Influence of Bicomponent Mixed Surfactants on Drop/Interface Coalescence

Effects of binary mixtures of ionic/nonionic (sodium dodecyl sulfate/2-heptanol or 1-decanol) and nonionic/nonionic surfactants (2-heptnol/1-decanol) on drop/interface coalescence of water drops in a continuous n-heptane phase were examined. The drop size reduced appreciably and the multi-step coalescence was suppressed finally as the concentration of each of the constituting components of surfactant mixture was increased. The drop became more stable in comparison to single surfactant systems. It was concluded that the mixed surfactants were much more effective on coalescence time and drop lifetime than single surfactant, particularly when one of the components was soluble in the drop phase.