“Surface and bulk properties of the aqueous Decytrimethylammonium Bromide – Hexadecyltrimethylammonium Bromide mixed system”

JOSÉ LUIS RODRÍGUEZ, MARÍA BELÉN SIERRA, PAULA MESSINA, MARCELA A. MORINI, PABLO CARLOS SCHULZ, PATRICIA DEL BURGO, ELENA JUNQUERA, ALBERTO RODRÍGUEZ, EMILIO AICART

JOURNAL OF COLLOID AND INTERFACE SCIENCE

Elsevier

Año: 2007 vol. 314 p. 699 - 706

0021-9797

Abstract The aqueous mixed system decyltrimethylammonium bromide (C10TAB)–hexadecyltrimethylammonium bromide (C16TAB) was studied by conductivity, ion-selective electrodes, surface tension, and fluorescence spectroscopy techniques. The mixture critical micelle concentration, cmc*, aggregation number, N., and micelle molar conductivity, Λcmc M , showed that the system aggregation is strongly nonideal. Both cmc* and10TAB)–hexadecyltrimethylammonium bromide (C16TAB) was studied by conductivity, ion-selective electrodes, surface tension, and fluorescence spectroscopy techniques. The mixture critical micelle concentration, cmc*, aggregation number, N., and micelle molar conductivity, Λcmc M , showed that the system aggregation is strongly nonideal. Both cmc* andN., and micelle molar conductivity, Λcmc M , showed that the system aggregation is strongly nonideal. Both cmc* and, showed that the system aggregation is strongly nonideal. Both cmc* and N. results were analyzed with two different procedures: (i) the regular solution theory on mixed micelles or Rubingh’s theory, and (ii) by the determination of the partial critical micelle concentration of the amphiphile component i in the presence of a constant concentration of the other amphiphile component, cmc.i . The Rubingh procedure gives micelles richer in C16TAB than the overall mixtures, while procedure (ii) gives micelles having the same composition as in the complete surfactant mixture (αC10TAB). Mixed micelles are larger than pure surfactant ones, with nonspherical shape. Using a literature model, the cause of the synergistic effect seems to be a reduction of the hydrocarbon/water contact at the micelle surface when mixed micelles form. Conductivity and ion-selective electrodes indicate that highly ionized premicelles form immediately before the cmc*. The air/solution interface is strongly nonideal and much richer in C16TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer.. results were analyzed with two different procedures: (i) the regular solution theory on mixed micelles or Rubingh’s theory, and (ii) by the determination of the partial critical micelle concentration of the amphiphile component i in the presence of a constant concentration of the other amphiphile component, cmc.i . The Rubingh procedure gives micelles richer in C16TAB than the overall mixtures, while procedure (ii) gives micelles having the same composition as in the complete surfactant mixture (αC10TAB). Mixed micelles are larger than pure surfactant ones, with nonspherical shape. Using a literature model, the cause of the synergistic effect seems to be a reduction of the hydrocarbon/water contact at the micelle surface when mixed micelles form. Conductivity and ion-selective electrodes indicate that highly ionized premicelles form immediately before the cmc*. The air/solution interface is strongly nonideal and much richer in C16TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer.i in the presence of a constant concentration of the other amphiphile component, cmc.i . The Rubingh procedure gives micelles richer in C16TAB than the overall mixtures, while procedure (ii) gives micelles having the same composition as in the complete surfactant mixture (αC10TAB). Mixed micelles are larger than pure surfactant ones, with nonspherical shape. Using a literature model, the cause of the synergistic effect seems to be a reduction of the hydrocarbon/water contact at the micelle surface when mixed micelles form. Conductivity and ion-selective electrodes indicate that highly ionized premicelles form immediately before the cmc*. The air/solution interface is strongly nonideal and much richer in C16TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer..i . The Rubingh procedure gives micelles richer in C16TAB than the overall mixtures, while procedure (ii) gives micelles having the same composition as in the complete surfactant mixture (αC10TAB). Mixed micelles are larger than pure surfactant ones, with nonspherical shape. Using a literature model, the cause of the synergistic effect seems to be a reduction of the hydrocarbon/water contact at the micelle surface when mixed micelles form. Conductivity and ion-selective electrodes indicate that highly ionized premicelles form immediately before the cmc*. The air/solution interface is strongly nonideal and much richer in C16TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer.αC10TAB). Mixed micelles are larger than pure surfactant ones, with nonspherical shape. Using a literature model, the cause of the synergistic effect seems to be a reduction of the hydrocarbon/water contact at the micelle surface when mixed micelles form. Conductivity and ion-selective electrodes indicate that highly ionized premicelles form immediately before the cmc*. The air/solution interface is strongly nonideal and much richer in C16TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer.16TAB than the composition in the bulk. When micelles form there is a strong desorption from the air/solution interface because micelles are energetically favored when compared with the monolayer. © 2007 Elsevier Inc. All rights reserved.2007 Elsevier Inc. All rights reserved. Keywords: Aggregation number; Conductivity; Critical micelle concentration; Decyltrimethylammonium bromide; Fluorescence; Hexadecyltrimethylammonium bromide; Ion-selective electrodes; Surface tensionAggregation number; Conductivity; Critical micelle concentration; Decyltrimethylammonium bromide; Fluorescence; Hexadecyltrimethylammonium bromide; Ion-selective electrodes; Surface tension