Structure of high internal phase aqueous-in-oil emulsions and related inverse micelle solutions. 3. Variation of surfactant

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dc.contributor.authorReynolds, PAen_AU
dc.contributor.authorGilbert, EPen_AU
dc.contributor.authorHenderson, MJen_AU
dc.contributor.authorWhite, JWen_AU
dc.date.accessioned2009-09-28T01:45:43Zen_AU
dc.date.accessioned2010-04-30T05:05:26Zen_AU
dc.date.available2009-09-28T01:45:43Zen_AU
dc.date.available2010-04-30T05:05:26Zen_AU
dc.date.issued2009-09-10en_AU
dc.date.statistics2009-09-10en_AU
dc.description.abstractThe small angle neutron scattering from high internal phase water-in-hexadecane and saturated ammonium nitrate-in-hexadecane emulsions is compared with that from related hexadecane-based inverse micellar solutions. Three molecular weights of the monodisperse polyisobutylene acid amide (PIBSA) surfactant 750, 1200, and 1700 were studied over a range of surfactant concentrations. As an additional comparison, emulsions based on sorbitan monooleate and isostearate surfactants were investigated. The scattering from molecular weight 1200 water-based PIBSA emulsions can be fitted at all concentrations to a model with a surfactant coated aqueous droplet-oil interface together with the majority of the surfactant in the oil phase of the emulsion in the form of inverse micelles. Variation of the molecular weight shows a variety of phases of increasing curvature: lamellar, sponge, and, most commonly, the emulsion structure described above. In addition, the molecular weight affects the oil component in the emulsions, which can contain either cylindrical micelles or spherical micelles of varying water but constant hexadecane content. Increased phase curvature is favored by both increased PIBSA molecular weight and ammonium nitrate dissolved in the water. These observations are consistent with "Wedge theory". The structures observed in the emulsions are close to those observed in related inverse micellar solutions made from hexadecane, the surfactant, and water. Lower concentrations of surfactant in the micellar solutions decrease micelle curvature, except where the inverse micelles are spherical and small; here, there is little effect of dilution. Substitution of sorbitan surfactants for PIBSAs produces slightly less organized but similar structures, with smaller spherical micelles containing proportionally more water. The aqueous-oil droplet interface has a relatively invariant monolayer of adsorbed surfactant. For all emulsions, we can infer from the mass balance that micelle concentrations are depressed in the inverse micellar solutions because up to half the added surfactant is present as individually dissolved molecules. © 2009, American Chemical Societyen_AU
dc.identifier.citationReynolds, P. A., Gilbert, E. P., Henderson, M. J., & White, J. W. (2009). Structure of high internal phase aqueous-in-oil emulsions and related inverse micelle solutions. 3. Variation of surfactant. Journal of Physical Chemistry B, 113(36), 12231-12242. doi:10.1021/jp903484jen_AU
dc.identifier.govdoc1352en_AU
dc.identifier.issn1520-6106en_AU
dc.identifier.issue36en_AU
dc.identifier.journaltitleJournal of Physical Chemistry Ben_AU
dc.identifier.pagination12231-12242en_AU
dc.identifier.urihttp://dx.doi.org/10.1021/jp903484jen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/1830en_AU
dc.identifier.volume113en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectSmall angle scatteringen_AU
dc.subjectSurfactantsen_AU
dc.subjectHexadecaneen_AU
dc.subjectEmulsionsen_AU
dc.subjectMicellar systemsen_AU
dc.subjectAqueous solutionsen_AU
dc.titleStructure of high internal phase aqueous-in-oil emulsions and related inverse micelle solutions. 3. Variation of surfactanten_AU
dc.typeJournal Articleen_AU
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