STUDY OF MIXED AGGREGATES IN AQUEOUS-SOLUTIONS OF SODIUM DODECYL-SULFATE AND DODECYLTRIMETHYLAMMONIUM BROMIDE

被引:74
作者
KAMENKA, N
CHORRO, M
TALMON, Y
ZANA, R
机构
[1] TECHNION ISRAEL INST TECHNOL,DEPT CHEM ENGN,IL-32000 HAIFA,ISRAEL
[2] UNIV MONTPELLIER,GDR NOUVEAUX MAT TENSIOACTIFS,F-34095 MONTPELLIER,FRANCE
[3] UNIV MONTPELLIER,PHYSICOCHIM SYST POLYPHASES LAB,F-34095 MONTPELLIER,FRANCE
来源
COLLOIDS AND SURFACES | 1992年 / 67卷
关键词
ANIONIC CATIONIC SURFACTANT MIXTURES; COUNTERION BINDING; CRYOTRANSMISSION ELECTRON MICROSCOPY; MIXED MICELLES; SELF-DIFFUSION; SURFACTANT-SPECIFIC ELECTRODES; VESICLE FORMATION;
D O I
10.1016/0166-6622(92)80300-Q
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Mixed solutions containing sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) have been investigated by tracer self-diffusion (Na+ and Cl- ion diffusion) and potentiometry with Br-- and DTA+-specific electrodes, with particular emphasis on the binding of counter-ions to the mixed micelles in the SDS-rich and DTAB-rich isotropic systems. At DTAB mole fractions (X) between 0 and 0.38 it has been shown that no Br- ion binding occurs, whereas all added DTA+ ions are incorporated in the mixed micelles. In the DTAB-rich systems, all added DS- ions are incorporated into mixed micelles, and the degree of Br- ion binding decreases upon increasing added SDS. However, it remains well above zero at the upper precipitation boundary (X = 0.88), in contrast to the degree of Na+ ion binding which tends toward zero at the lower precipitation boundary (X = 0.38). This difference in counter-ion binding in the two composition ranges correlates well with the reported changes of micelle size in these ranges. Finally, in the range 0.32<X<0.38, which corresponds to turbid but stable systems, the self-diffusion data suggest the existence of vesicles and/or more-complex surfactant assemblies. Direct examination of the solutions by phase-contrast light microscopy and cryo-transmission electron microscopy (cryo-TEM) has confirmed this conclusion, and has shown the existence of highly polydisperse, sometimes open, vesicles which are spontaneously formed in solutions of mixtures of SDS and DTAB at X = 0.34. Cryo-TEM also shows that some thread-like micelles coexist with the vesicles at X = 0.34. At X 0.30 the micelles are mostly spheroidal or slightly elongated. The micrographs also show some open vesicles.
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页码:213 / 222
页数:10
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