Effect of counterions on the shape, hydration, and degree of order at the interface of cationic micelles the triflate case

Effect of counterions on the shape, hydration, and degree of order at the interface of cationic micelles : the triflate case

Specific ion effects in surfactant solutions affect the properties of micelles. Dodecyltrimethylammonium chloride (DTAC), bromide (DTAB), and methanesulfonate (DTAMs) micelles are typically spherical, but some organic anions can induce shape or phase transitions in DTA(+) micelles. Above a defined c...

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Veröffentlicht in:Langmuir : the ACS journal of surfaces and colloids. - 1992. - 29(2013), 13 vom: 02. Apr., Seite 4193-203
1. Verfasser: Lima, Filipe S (VerfasserIn)
Weitere Verfasser: Cuccovia, Iolanda M, Horinek, Dominik, Amaral, Lia Q, Riske, Karin A, Schreier, Shirley, Salinas, Roberto K, Bastos, Erick L, Pires, Paulo A R, Bozelli, José Carlos Jr, Favaro, Denize C, Rodrigues, Ana Clara B, Dias, Luís Gustavo, El Seoud, Omar A, Chaimovich, Hernan
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2013
Zugriff auf das übergeordnete Werk:Langmuir : the ACS journal of surfaces and colloids
Schlagworte:Journal Article Research Support, Non-U.S. Gov't Cations Mesylates Micelles Quaternary Ammonium Compounds Surface-Active Agents dodecyltrimethylammonium triflate dodecyltrimethylammonium GT3793XV5S mehr... trifluoromethanesulfonic acid JE2SY203E8
Beschreibung
Zusammenfassung:Specific ion effects in surfactant solutions affect the properties of micelles. Dodecyltrimethylammonium chloride (DTAC), bromide (DTAB), and methanesulfonate (DTAMs) micelles are typically spherical, but some organic anions can induce shape or phase transitions in DTA(+) micelles. Above a defined concentration, sodium triflate (NaTf) induces a phase separation in dodecyltrimethylammonium triflate (DTATf) micelles, a phenomenon rarely observed in cationic micelles. This unexpected behavior of the DTATf/NaTf system suggests that DTATf aggregates have unusual properties. The structural properties of DTATf micelles were analyzed by time-resolved fluorescence quenching, small-angle X-ray scattering, nuclear magnetic resonance, and electron paramagnetic resonance and compared with those of DTAC, DTAB, and DTAMs micelles. Compared to the other micelle types, the DTATf micelles had a higher average number of monomers per aggregate, an uncommon disk-like shape, smaller interfacial hydration, and restricted monomer chain mobility. Molecular dynamic simulations supported these observations. Even small water-soluble salts can profoundly affect micellar properties; our data demonstrate that the -CF3 group in Tf(-) was directly responsible for the observed shape changes by decreasing interfacial hydration and increasing the degree of order of the surfactant chains in the DTATf micelles
Beschreibung:Date Completed 26.09.2013
Date Revised 25.11.2016
published: Print-Electronic
Citation Status MEDLINE
ISSN:1520-5827
DOI:10.1021/la304658e