Mixed vesicle formation on a ternary surfactant system: didodecyldimethylammonium bromide/dodecylethyldimethylammonium bromide/water.
The formation of mixed aggregates has been investigated on a ternary system consisting of two cationic surfactants with similar polar heads and two and/or one 12 carbon atom hydrophobic tail, respectively, didodecyldimethylammonium bromide and dodecylethyldimethylammonium bromide and water. The study has been carried out by means of conductivity, zeta potential, and cryogenic transmission electronic microscopy (cryo-TEM) experiments on the very diluted region. A variety of mixed aggregates, microaggregates, vesicles, and micelles has been found, depending on system composition and total surfactant concentration. Mixed critical microaggregate concentration and mixed critical vesicle concentration have been determined from conductivity data. Furthermore, zeta potential and cryo-TEM experiments allow for the characterization of the aggregates/solution interface and of the shape and size of the aggregates. This experimental evidence has also been analyzed in terms of the theoretical packing parameter, P.
Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040-Madrid, Spain.
Elena
E
Junquera
Rocío
R
Arranz
Emilio
E
Aicart
D004553:Electric Conductivity; D008823:Micelles; D046529:Microscopy, Electron, Transmission / Q000379:methods; D010316:Particle Size; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D008823:Micelles; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D014867:Water; C046112:didodecyldimethylammonium; C015831:dimethyldioctadecylammonium