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Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/16031

The influence of surfactant mixing ratio on nano-emulsion formation by the pit method

AutorIzquierdo, P.; Feng, Jin; Esquena, Jordi; Tadros, Tharwat F.; Dederen, Joseph C.; García, María José; Azemar Sazatornil, Nuria; Solans, Conxita
Palabras claveNano-emulsion
Mixed surfactant system
HLB temperature
Emulsion stability
Phase behavior
Ostwald ripening
Phase inversion temperature (PIT) method
Fecha de publicación1-may-2005
CitaciónJournal of Colloid and Interface Science 285(1): 388-394 (2005)
ResumenThe formation of O/W nano-emulsions by the PIT emulsification method in water/mixed nonionic surfactant/oil systems has been studied. The hydrophilic–lipophilic properties of the surfactant were varied by mixing polyoxyethylene 4-lauryl ether (View the MathML source) and polyoxyethylene 6-lauryl ether (View the MathML source). Emulsification was performed in samples with constant oil concentration (20 wt%) by fast cooling from the corresponding HLB temperature to 25 °C. Nano-emulsions with droplet radius 60–70 nm and 25–30 nm were obtained at total surfactant concentrations of 4 and 8 wt%, respectively. Moreover, droplet size remained practically unchanged, independent of the surfactant mixing ratio, XC12E6. At 4 wt% surfactant concentration, the polydispersity and instability of nano-emulsions increased with the increase in XC12E6. However, at 8 wt% surfactant concentration, nano-emulsions with low polydispersity and high stability were obtained in a wide range of surfactant mixing ratios. Phase behavior studies showed that at 4 wt% surfactant concentration, three-liquid phases (W + D + O) coexist at the starting emulsification temperature. Furthermore, the excess oil phase with respect to the microemulsion D-phase increases with the increase in XC12E6, which could explain the increase in instability. At 8 wt% surfactant concentration, a microemulsion D-phase is present when emulsification starts. The low droplet size and polydispersity and higher stability of these nano-emulsions have been attributed, in addition to the increase in the surface or interfacial activity, to the spontaneous emulsification produced in the microemulsion D-phase.
Descripción7 pages, 6 figures, 2 tables.-- PMID: 15797437 [PubMed].-- Available online Dec 23, 2004.
Versión del editorhttp://dx.doi.org/10.1016/j.jcis.2004.10.047
ISSN0021-9797 (Print)
1095-7103 (Online)
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