Vesicle-to-micelle transition in dioctadecyldimethylammonium bromide and dioctadecyldimethylammonium chloride dispersions induced by octaethylene glycol n-dodecyl monoether. An isothermal titration calorimetry study

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Autor(es): dc.contributorUniversity of Lund-
Autor(es): dc.contributorUniversidade Estadual Paulista (UNESP)-
Autor(es): dc.creatorBarreleiro, P. C.A.-
Autor(es): dc.creatorOlofsson, G.-
Autor(es): dc.creatorFeitosa, E.-
Data de aceite: dc.date.accessioned2025-08-21T20:24:06Z-
Data de disponibilização: dc.date.available2025-08-21T20:24:06Z-
Data de envio: dc.date.issued2022-04-28-
Data de envio: dc.date.issued2022-04-28-
Data de envio: dc.date.issued2000-12-01-
Fonte completa do material: dc.identifierhttp://hdl.handle.net/11449/224187-
Fonte: dc.identifier.urihttp://educapes.capes.gov.br/handle/11449/224187-
Descrição: dc.descriptionWe have used isothermal titration calorimetry to investigate the vesicle-to-micelle transition in dioctadecyldimethylammonium bromide (DODAB) and chloride (DODAC) vesicle dispersions induced by the nonionic surfactant octaethylene glycol n-dodecyl monoether (C12E8) at room temperature. Small and giant unilamellar vesicles were prepared by sonication and without sonication, respectively, of the pure cationic surfactants at low concentrations in water. The titration of 1.0 mM DODAX (X = Cl- and Br-) by a concentrated micellar solution of C12E8 shows that the enthalpy of interaction (ΔHobs) of C12E8 in micellar form with DODAX is always endothermic. The titration curves are understood on the basis of superposition of the enthalpies of partitioning of C12E8 into the bilayer, of micelle formation and of vesicle-to-micelle transformation. The enthalpy, ΔHobs, initially increases owing to the incorporation of C12E8 into the vesicle bilayer until the C12E8/DODAX saturation ratio (Rsat) is reached, then ΔHobs decreases, in different ways for DODAB and DODAC, owing to degradation of vesicles and formation of mixed micelles and intermediary structures up to the C12E8/ DODAX solubilization ratio, Rsol. Above Rsol only mixed micelles exist. The surfactant solubilization takes place in three stages. All the critical ratios are lower for DODAB than for DODAC, meaning that C12E8 solubilizes more strongly in DODAB; for example, Rsat is 0.8 for DODAB and 1.2 for DODAC. Sonication has no significant effect on the transition. © Springer-Verlag 2000.-
Descrição: dc.descriptionPhysical Chemistry 1 Center for Chemistry and Chemical Engineering University of Lund, P.O. Box 124, 221 00 Lund-
Descrição: dc.descriptionPhysics Department IBILCE/UNESP, 15054-000 Sao Jose do Rio Preto, SP-
Descrição: dc.descriptionPhysics Department IBILCE/UNESP, 15054-000 Sao Jose do Rio Preto, SP-
Formato: dc.format33-36-
Idioma: dc.languageen-
Relação: dc.relationProgress in Colloid and Polymer Science-
???dc.source???: dc.sourceScopus-
Palavras-chave: dc.subjectCationic vesicles-
Palavras-chave: dc.subjectDioctadecyldimethylammonium bromide-
Palavras-chave: dc.subjectDioctadecyldimethylammonium chloride-
Palavras-chave: dc.subjectIsothermal titration calorimetry-
Palavras-chave: dc.subjectSurfactant solubilization-
Título: dc.titleVesicle-to-micelle transition in dioctadecyldimethylammonium bromide and dioctadecyldimethylammonium chloride dispersions induced by octaethylene glycol n-dodecyl monoether. An isothermal titration calorimetry study-
Tipo de arquivo: dc.typelivro digital-
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