(615f) Interfacial Properties and Spontaneous Emulsification with Block Copolymer Surfactants

Block copolymer surfactants at air/water interfaces have been studied in detail for several decades, but little data exist on their adsorption to oil/water interfaces. We have characterized the dynamic adsorption behavior of several oil-soluble polyethylene oxide-b-polydimethylsiloxane surfactants with the ability to spontaneously emulsify oil/water interfaces using a microtensiometer platform. This platform permits accurate determination of the initial stages of adsorption, allowing for precise determination of the adsorption mechanism for given solution conditions. After adsorption, dilatational mechanics are probed either with or without surfactant in the bulk. Adsorption dynamics are strongly influenced by the curvature of the interface (a tunable parameter of the microtensiometer platform), allowing adsorption timescales to be varied over a wide range. The influence of surfactant architecture on interfacial properties and the link with the ability of these molecules to spontaneously emulsify oil/water interfaces will be discussed.