Explanation of Experimental Results of Mixed Micelles of Homologous Surfactants through

MARÍA LUJÁN FERREIRA; MARÍA BELÉN SIERRA; MARCELA MORINI; JOSÉ LUIS RODRÍGUEZ; ROSANA MINARDI; PABLO SCHULZ

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Año: 2010 vol. 114 p. 14924 - 14933

1520-6106

A computational modeling (in gas phase) to study the disposition of the homologous surfactants in a bidimensional simple model of mixed and homogeneous micelles was performed for the case of R-trimethylammonium bromide surfactants with different linear R lengths from R ) C5 to C17. First, the bidimensional homogeneous (one component) micelle was modeled, and as a second step, heterogeneous (two components) bidimensional micelles were modeled. The difference in the number of carbon atoms betweenhydrocarbon chains of the surfactants in the heterogeneous micelles,  ranged from 2 to 8. Results were  contrasted with experimental data obtained at our own laboratory. The exothermic values of the steric energy changes showed strong attraction between components of homologous surfactants mixture, especially when one of the surfactants has a long chain. It may be argued that the inclusion of a shorter surfactant in the mixture and the twisting of the longer surfactant makes the bidimensional arrangement formation more exothermic. All predictions were in agreement with previous experimental results.