Browsing by Author "Grillo, I"

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    Fluorinated lamellar phases: structural characterisation and use as templates for highly ordered silica materials
    (Royal Society of Chemistry, 2014-05-13) Pottage, MJ; Tiara, K; Grillo, I; Garvey, CJ; Stickland, AD; Tabor, RF
    Highly ordered silica was synthesised by using a lamellar phase comprising the anionic fluorinated surfactant sodium perfluorooctanoate and the partially-fluorinated co-surfactant/oil 1H,1H,2H,2H-perfluorooctan-1-ol in water. The phase behaviour of this system was thoroughly analysed, and it was found that even low levels of the alcohol (<0.5 mol%) were sufficient to induce a phase change from normal micelles to a lamellar phase, rationalised as a result of geometric and electrostatic effects. The properties of these phases were compared to their hydrocarbon analogues, demonstrating the unique and valuable properties exhibited by fluorocarbons, directly related with the observed nanostructure. Small-angle neutron scattering was used to analyse the internal structure of the systems, providing information on the inter-lamellar spacing, bilayer thickness and membrane elasticity. The potential for these phases to act as shear-thinning lubricants was assessed using oscillatory rheology, obtaining shear-dependent viscosity along with storage and loss moduli.© 2014, The Royal Society of Chemistry.
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    Phase behavior, small-angle neutron scattering and rheology of ternary nonionic surfactant-oil-water systems: a comparison of oils
    (American Chemical Society, 2013-03-19) Tabor, RF; Zayeer, MI; Dagastine, RR; Grillo, I; Garvey, CJ
    The phase behavior of the nonionic surfactant Triton X-100 (polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether) was studied in two three-component systems: Triton-water-p-xylene and Triton-water-trichloroethylene. It was found that the aromatic solvent was able to produce monophasic soft matter systems at a significantly greater range of compositions. The structural characteristics of the phases generated were analyzed by small-angle neutron scattering, showing evidence for microemulsion, lamellar, and reverse-rnicroemulsion phases. In addition, for the Triton-water-p-xylene system, an L-3 "sponge" phase was found in a water-rich region of the phase diagram and the properties of this were examined using rheological measurements. The differences in phase behavior are discussed in light of the solvation properties of the surfactant in the different solvents studied. Most notably, xylene appears to favor phases with low-curvature interfaces, suggesting preferential solvation of the central phenyl group of Triton. © 2013, American Chemical Society.