8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P6.12Fri 911:10-14:00Studies on nanoemulsions formed by low-energy phaseinversion concentration (PIC) methodPeggy Heunemann, 1 Sylvain Prévost, 2 Michael Bernicke, 3 Michael Gradzielski, 3and Isabelle Grillo 41 Institut Laue-Langevin, 6, Rue Jules Horowitz, 38042, Grenoble, France2 Helmholtz Zentrum Berlin, Berlin, Germany3 TU-Berlin, Berlin, Germany4 Institut Laue Langevin, Grenoble, FranceMetastable nanoemulsions, structurally located between thermodynamically stable microemulsions(< 10 nm.) and macroemulsions (> 200 nm.), are kinetically relatively stable againstbreakdown processes. Typically they are formed by high energy input homogenizers or ultrasonication.In contrast, the formation of nanoemulsions by means of low energy input methods is avery interesting phenomenon both from a fundamental scientific point of view but also for manyapplications as the nanosized dispersion of an oil in water (o/w) or vice versa shall be achieved bya simple preparation method. In particular, we are interested in the Phase-Inversion-Concentration(PIC) method that forms nanoemulsions at a certain oil/water-ratio due to the change of interfacialcomposition during dilution. Our work is based on an industrial formulation (Tego Wipe DE) [1]that we modified in a systematic fashion with respect to the composition of the surfactant and oilcomponents. We studied the structural progression along the dilution pathway by verious physicochemicalcharacterisation techniques such as conductivity, viscosity and UV/Vis-transmittancemeasurements. Small-angle neutron and x-ray scattering yield a more refined structural pictureof the formed phases and revealed, with coplementary cryo-TEM micrographs, a bimodal sizedistribution respectively [2]. Time resolved SANS/SAXS and turbidity measurements showeda very fast spontaneous emulsification process that is faster than 100ms. and is triggered bythe dissolution of the cosurfactant into the aqueous phase upon dilution pathway. Using SANSand NMR-techniques we could validate the general assumption for the PIC-mechanism that thecosurfactant is facilitating the high effective solubilisation of the system and becomes leached outfrom the emulsion droplets upon dilution due to its relatively high hydrophilicity.[1] J. Meyer et al. , Cosmetics Toiletries 2007, 122, 63-68.[2] P. Heunemann et al. , Soft Matter, in print12