Surface Activity of the Triflate Ion at the Air/Water Interface and Properties of N,N,N-Trimethyl-N-Dodecylammonium Triflate Aqueous Solutions


Autoria(s): LIMA, F. S.; Maximiano, Flavio Antonio; Cuccovia, Iolanda Midea; CHAIMOVICH, H.
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

20/10/2012

20/10/2012

2011

Resumo

The surface activity of salts added to water is Air orders of magnitude lower than that of surfactants. Sodium trifluoromethanesulfonate (NaTf) produced a change in surface tension. with concentration, Delta gamma/Delta c, of -13.2 mN.L/m.mol. This value is ca. 4-fold larger than those of simple salts and that of methanesulfonate. This unexpected surface effect suggested that positively charged micelles containing Tf could exhibit interesting properties. Dodecyltrimethylammonium triflate (DTATf) had a higher Kraft temperature (37 degrees C) and a lower cmc (5 x 10(-3)M) and degree of dissociation (0.11) than the chloride and bromide salts of DTA. Above the Kraft temperature, at a characteristic temperature t(1), the addition of NaTf above 0.05 M. to a DTATf solution induced phase separation. By increasing the temperature of the two-phase system to above t(1), a homogeneous, transparent solution was obtained at a characteristic temperature t(2). These results, together with well-known triflate properties, led us to suggest that the Tf ion pairs With DTA and that the -CF(3) group may be dehydrated in the interfacial region, resulting in new and interesting self-aggregated structures.

FAPESP[2007/50970-5]

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

CNPq

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Instituto Nacional de Ciencia e Tecnologia de Fluidos Complexos, INCT-FCx

Instituto Nacional de Ciencia e Tecnologia de Fluidos Complexos, INCT-FCx[573560/2008-0]

Identificador

LANGMUIR, v.27, n.8, p.4319-4323, 2011

0743-7463

http://producao.usp.br/handle/BDPI/30926

10.1021/la2004613

http://dx.doi.org/10.1021/la2004613

Idioma(s)

eng

Publicador

AMER CHEMICAL SOC

Relação

Langmuir

Direitos

closedAccess

Copyright AMER CHEMICAL SOC

Palavras-Chave #MICELLE FORMATION #CLOUD-POINT #ELECTROLYTE SOLUTIONS #CATIONIC MICELLES #DODECYL-SULFATE #ROD TRANSITION #SODIUM #PHASE #MICELLIZATION #CHLORIDE #Chemistry, Multidisciplinary #Chemistry, Physical #Materials Science, Multidisciplinary
Tipo

article

original article

publishedVersion