| Texto completo | |
| Autor(es): |
de Souza, Renato Nunes
[1]
;
Jora, Manazael Zuliani
[1]
;
Alves Duarte, Luis Gustavo Teixeira
[1]
;
Clincks, Karl Jan
[1]
;
Zambon Atvars, Teresa Dib
[1]
;
Sabadini, Edvaldo
[1]
Número total de Autores: 6
|
| Afiliação do(s) autor(es): | [1] Univ Estadual Campinas, UNICAMP, Inst Chem, Phys Chem Dept, POB 6154, BR-13084862 Campinas, SP - Brazil
Número total de Afiliações: 1
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Colloid and Interface Science; v. 552, p. 794-800, SEP 15 2018. |
| Citações Web of Science: | 3 |
| Resumo | |
Hypothesis: When tetradecyltrimethylammonium bromide, TTAB, is added to aqueous solution of sodium salicylate, NaSal, the threading of the aromatic anion into the micellar palisade leads to the formation of wormlike micelles. Based on the calorimetric titration of NaSal with TTAB, and on the lifetime of fluorescence of salicylate, we propose that the aggregation of the two components directly leads to the formation of wormlike micelles, without any pre-aggregation. Experiments: By using an isothermal titration calorimeter, aliquots of TTAB were added to a dilute solution of NaSal. The energy involved in each addition was then integrated and the variation of enthalpy was determined. In the same range of concentrations and molar ratios, the surface tensiometry and time-resolved emission spectroscopy experiments were performed. Findings: A very characteristic calorimetric signal associated with wormlike micelle formation was obtained, being the enthalpy variation of this process, Delta H-WLM(298)0 < 0. When 1.2 mmol L-1 of NaSal is titrated with 11.0 mmol L-1 of TTAB at 298.15 K, Delta H-f(298)0 = -10.31 kJ per mol of injectant. By adding TTAB to NaSal solution, two fluorescence lifetimes of salicylate were observed solely after wormlike micelle being formed. The correspondent lifetime values of 4.0 ns and 7.2 ns are respectively associated with the free and associated species of salicylate. The new results demonstrated that wormlike micelles are the first aggregate formed when TTAB is added to salicylate. This aspect is relevant for understanding the mechanism of wormlike micelles formation. (C) 2019 Elsevier Inc. All rights reserved. (AU) | |
| Processo FAPESP: | 13/16245-2 - Propriedades fotofísicas de filmes finos de polímeros conjugados |
| Beneficiário: | Teresa Dib Zambon Atvars |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 15/25406-5 - Organizando a matéria: colóides formados por associação de surfactantes, polímeros e nanopartículas |
| Beneficiário: | Watson Loh |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |