Monolayers of gemini surfactants and their catanionic mixtures with sodium dodecyl sulfate at the air-water interface: Chain length and composition effects

• Tipo: Artigo em Revista Científica Internacional
• Data: 2008

Autores

Yujie J Wang (Autor) Outra; Eduardo F Marques (Autor) FCUP; Carlos M Pereira (Autor) FCUP

Revista

Título: Thin Solid Films

Vol. 516 Nº 1

Páginas: 7458-7466

ISSN: 0040-6090

Editora: Elsevier

Indexação

ISI Web of Knowledge - 28 Citações

Scopus - 28 Citações

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia dos materiais

Outras Informações

ID Authenticus: P-003-WVZ

DOI: 10.1016/j.tsf.2008.03.029

Abstract (EN): Monolayers of cationic gemini surfactants and their catanionic mixtures with sodium dodecyl sulfate (SDS), have been investigated with the Langmuir trough technique, at the air-water interface. The gemini surfactants are of the alkanediyl-alpha,omega-bis(alkyldimethylammonium) type, here designated as m-2-m, where m and 2 are the alkyl chain and spacer lengths, respectively. For the neat geminis, the stability of the monolayer increases as the chain length increases, starting from soluble films of 12-2-12 to stable films of 18-2-18. For the equicharged m-2-m/SDS mixtures (with m=12, 14, 16 and 18), stable monolayers are obtained. The effect of the gemini chain length on the phase behavior and molecular organization of the films is discussed on the basis of pressure-area isotherms for compression or compression-expansion cycles. The pressure-temperature plots, at constant trough area, yield the desorption temperature and suggest the desorption mechanism of the film molecules. Furthermore, the effect of the mixing molar ratio between m-2-m and SDS on the isotherms, for m = 12 and 14, has also been investigated. It is concluded from the mean area per molecule that the gemini molecules when in excess with respect to equicharged composition desorb from the film, so that the electroneutral composition is maintained.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 9