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Infrared Spectroscopy of Anionic, Cationic, and Zwitterionic Surfactants

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Autor(es):
Viana, Rommel B. ; da Silva, Alberico B. F. ; Pimentel, Andre S.
Número total de Autores: 3
Tipo de documento: Artigo Científico
Fonte: ADVANCES IN PHYSICAL CHEMISTRY; v. N/A, p. 14-pg., 2012-01-01.
Resumo

This paper describes the ordering degree of anionic, cationic, and zwitterionic surfactants with the increase of their packing density on Ge substrate by using Fourier transforminfrared-attenuated total reflection (FTIR-ATR) spectroscopy. This work shows new insights on the conformational order of sodium dodecyl sulfate (SDS), N-hexadecyl-N-N-dimethyl-3-ammonio-1-propane-sulfonate (HPS), hexadecyl-trimethylammonium bromide (CTAB), and dodecyl trimethylammonium bromide (DTAB). DFT and semiempirical calculations are also performed in order to evaluate the effect of headgroup hydration and counterion. The CH2 asymmetric and symmetric stretching bands for the SDS molecule show a shift of 1.7 and 0.9 cm(-1) to higher frequencies as the packing density increases, while it is observed a shift of 2.6 and 2.7 cm(-1) for the HPS molecule, respectively. The DTAB molecule shows a shift of 4.5 cm(-1) to lower frequencies for both CH2 asymmetric and symmetric stretching bands as the packing density increases, indicating the decrease of gauche conformations and the increase of all-trans conformations over the aliphatic chain. (AU)

Processo FAPESP: 04/08227-5 - A formação heterogênea de HNO2 a partir da reação interfacial de NO2 com monocamadas de H2O
Beneficiário:André Silva Pimentel
Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores