Silicone/vegetable oil Janus emulsion: Topological stability versus interfacial tensions and relative oil volumes

Silicone/vegetable oil Janus emulsion: Topological stability versus interfacial tensions and relative oil volumes

Author Leonardi, G. R. Autor UNIFESP Google Scholar
Perrechil, F. A. Autor UNIFESP Google Scholar
Silveira, L. P. Autor UNIFESP Google Scholar
Brunca, H. O. Autor UNIFESP Google Scholar
Friberg, S. E. Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
NTNU
Abstract Several aspects were studied of the formation and destabilization in bulk of silicone/vegetable oil, SO/VO, Janus emulsions, stabilized by Tween 80. in the formation of the emulsions, it was unexpectedly found that the dispersions tended to contain both single and flocculated drops irrespective of the emulsification intensity. Microscopy of the emulsions with no cover glass revealed flocculated drops of a large (200-500 mu m) central SO drop with many small VO drops attached. Applying a cover glass did not significantly change the drop size; instead two-oil Janus drops of well-defined contact angle were found. the emulsions showed rapid creaming irrespective of the preparation method, but a few days storage did not significantly change the drop size in the creamed layer, nor was separation of the oils detected. the total interfacial free energy of the Janus drops at equilibrium was compared to the two relevant alternatives; engulfed and separate drops. the Janus drop free energies were found less for all volume ratios of the oils, when the surfactant concentrations in the aqueous phase was sufficient to prevent spreading of VO on SO. Changing the surfactant concentration to bring the interfacial tensions closer to the critical value for spreading gave declining interfacial free energy difference to that of engulfed drops. (C) 2014 Elsevier Inc. All rights reserved.
Keywords Emulsions
Janus drops
Emulsion stability
Interfacial tension
Emulsion free energy
Preparation Janus emulsions
Language English
Sponsor Ugelstad Laboratory (Norway)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Grant number CNPq: 800075/2014-5
Date 2015-07-01
Published in Journal of Colloid and Interface Science. San Diego: Academic Press Inc Elsevier Science, v. 449, p. 31-37, 2015.
ISSN 0021-9797 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 31-37
Origin http://dx.doi.org/10.1016/j.jcis.2014.09.028
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000353848300005
URI http://repositorio.unifesp.br/handle/11600/39146

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