Interplay between bulk self-assembly, interfacial and foaming properties in a catanionic surfactant mixture of varying composition

• Tipo: Artigo em Revista Científica Internacional
• Data: 2017

Autores

Ferreira, J (Autor) Outra; Mikhailovskaya, A (Autor) Outra; Chenneviere, A (Autor) Outra; Restagno, F (Autor) Outra; Cousin, F (Autor) Outra; Muller, F (Autor) Outra; Degrouard, J (Autor) Outra; Salonen, A (Autor) Outra; Eduardo F Marques (Autor) FCUP

Revista

Título: Soft Matter

Vol. 13

Páginas: 7197-7206

ISSN: 1744-683X

Editora: Royal Society of Chemistry

Indexação

ISI Web of Knowledge - 23 Citações

Scopus - 27 Citações

Outras Informações

ID Authenticus: P-00N-3S0

DOI: 10.1039/c7sm01601h

Abstract (EN): The self-aggregation, surface properties and foamability of the catanionic surfactant mixture cetyltrimethylammonium bromide (CTAB)/sodium octyl sulfonate (SOSo) have been investigated to obtain insight on the relation between bulk nanostructures, surfactant packing, and foam stability and aging. Light microscopy, SANS, cryo-TEM, DLS, surface tension, rheometry and direct photography were used to characterize mixtures with varying CTAB molar fraction, xCTAB. In the bulk, self-assembly is richer in the excess CTAB region than in the excess SOSo one. Starting from neat CTAB micelles and on addition of anionic surfactant, there is a change from small ellipsoidal micelles (1 < x(CTAB) <= 0.80) to large rodlike micelles (0.65 <= x(CTAB) < 0.55) and then to vesicles (0 < x(CTAB) <= 0.50), with coexistence regions in between; SOSo-rich mixtures are thus dominated by vesicles. High size polydispersity for the micelles and vesicles is an intrinsic feature of this system. Foam stability is concomitantly impacted by xCTAB. SOSo is a small mobile molecule and so it disrupts foam stability, irrespective of the presence of vesicles. Foams are thus only stable in the CTAB-rich regions, and SANS shows that the shape of micelles and vesicles is unchanged inside the foam. Foam drainage is thereby mostly controlled by the presence of the elongated micelles through the solution viscosity, whereas coarsening is influenced by dense surfactant packing at the gas-liquid interfaces.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 10