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American Chemical Society, Langmuir, 8(27), p. 4319-4323, 2011

DOI: 10.1021/la2004613

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

Journal article published in 2011 by F. S. Lima, F. A. Maximiano, I. M. Cuccovia ORCID, H. Chaimovich
This paper was not found in any repository; the policy of its publisher is unknown or unclear.
This paper was not found in any repository; the policy of its publisher is unknown or unclear.

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Abstract

The surface activity of salts added to water is orders of magnitude lower than that of surfactants. Sodium trifluoromethanesulfonate (NaTf) produced a change in surface tension with concentration, Δγ/Δc, 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 °C) and a lower cmc (5 × 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.