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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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Lima, F. S. [1] ; Maximiano, F. A. [1] ; Cuccovia, I. M. [1] ; Chaimovich, H. [1]
Total Authors: 4
[1] Univ Sao Paulo, Inst Quim, BR-05508 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Langmuir; v. 27, n. 8, p. 4319-4323, APR 19 2011.
Web of Science Citations: 15

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. (AU)

FAPESP's process: 07/50970-5 - Chemical and biological reactivity in interfaces
Grantee:Hernan Chaimovich Guralnik
Support Opportunities: Research Projects - Thematic Grants