(623i) Conformable Molecularly Thin Pouches to Hold Oil Droplets in Solution

We describe the development of a novel concept of coating the oil-water interface with a self-assembled molecularly thin film which acts as a skin on oil droplets stabilizing them against coalescence. Such Pickering emulsion type systems involve the use of metal-organic frameworks (MOF) that are flexible and conform to the curvature of the droplet. The films thus act as micron scale pouches to hold oil droplets. Pendant drop tensiometry shows that the molecular films self-assemble at hexadecane-water interface forming a capsule around a pendant droplet. Fluid filling and withdrawal of the pendant droplet show smoothening and wrinkling of the skin, verifying the dynamic stability and elasticity of the film. The films are therefore entirely different from the rigid two-dimensional films at the oil-water interface formed by materials such as graphene/graphene oxide. The films are based on the use of flat polyphenolics coordinated with transition metal ions such as Fe(III) and were first reported by Ejima et al. (Science 2013) and the use here to form Pickering emulsions is a new concept. Our work will describe both the fundamental characterization of these films and applications to emulsion formation and emulsion stability.