RT Journal Article
T1 Micellization of dodecyldimethyl-N-2-phenoxyethylammonium bromide (domiphen) in aqueous solution. Comparison with other alkyl ammonium surfactants
A1 Vázquez-Gómez, Silvia
A1 Vázquez Tato, María del Pilar
A1 Seijas Vázquez, Julio Antonio
A1 Meijide del Río, Francisco Ángel
A1 Vázquez Tato, José
A1 Fraga López, Francisco
K1 Dodecyldimethyl-N-2-phenoxyethylammonium bromide
K1 Domiphen
K1 Aggregation
K1 Thermodynamics of demicellization
K1 Alkylammonium surfactants
AB Dodecyldimethyl-N-2-phenoxyethylammonium bromide (domiphen) is a quaternary ammonium salt which has been used in oral hygiene long time ago. The published studies on its characterization as surfactant evidence several contradictory results. In this paper, measurements of surface tension, conductimetry, fluorescence and mainly isotermal titration calorimetry (ITC) have been performed at different temperatures. The enthalpy of demicellization varies linearly with temperature in the interval 15–45 °C, from which a value of 704 ± 39 J mol−1K−1 in water has been determined for the change of heat capacity. The obtained results are compared with published values for alkyltrimethylammonium bromides with different alkyl chain lengths (CnTAB). For instance, its critical micelle concentration, cmc, is almost ten times lower than that of C12TAB. The substitution of one methyl group by the phenoxyethyl has a strong influence on the behavior of domiphen making it equivalent to a CnTAB surfactant with n = 15–19 methylene groups, the number depending on the studied property. From ITC an average aggregation number of 45 ± 3 is obtained in good agreement with the one from fluorescence quenching of pyrene equal to 44.5–47.6. From the analysis of specific conductivity, the fraction of bound counterions to micelles was obtained, the values linearly decreasing with temperature. Below cmc domiphen behaves as a strong 1:1 electrolyte without association of monomers. Other themodynamic parameters have also been obtained. The fjord and reef hydration models are used to propose a structure for domiphen micelles.
PB Elsevier
SN 0167-7322
YR 2023
FD 2023
LK http://hdl.handle.net/10347/33006
UL http://hdl.handle.net/10347/33006
LA eng
NO Journal of Molecular Liquids Volume 390, Part B, 15 November 2023, 123109
NO The authors thank the Ministerio de Economía, Industria y Competitividad (Spain) (Project MAT2017-86109-P) for financial support.
DS Minerva
RD 22 abr 2026