Interface of Mixed Micelles Formed of Anionic—Cationic and Ionic—Nonionic Surfactants
1992; American Chemical Society; Linguagem: Inglês
10.1021/bk-1992-0501.ch010
ISSN1947-5918
AutoresPiero Baglioni, Luigi Dei, Larry Kevan, Elisabeth Rivara‐Minten,
Tópico(s)Spectroscopy and Quantum Chemical Studies
ResumoElectron spin echo modulation (ESEM) and electron spin resonance of x-doxylstearic acids spin probes (x-DSA, x = 5, 7, 10, 12, and 16) in mixed micellar solutions of sodium dodecylsulfate (SDS) and dodecyltrimethylammonium chloride (DTAC) or mixed micelles of SDS, DTAC and hexakis(ethyleneglycol)monododecyl ether (C12E6), have been studied as a function of the mixed micelle composition m H2O and D2O. Analysis of the ESR parameters shows a strong decrease of the polarity and a strong increase of the microviscosity of the surface of SDS/DTAC mixed micelle, as compared to pure micelles. ESEM effects due to x-DSA interaction with water deuteriums give direct evidence that changes in the surface hydration of the mixed micelle are present. It is also shown in the SDS/C12E6 or DTAC/C12E6 mixed micelles that the polar headgroups of the anionic and cationic surfactants are located in the ethylene oxide region of C12E6. The average location of SDS and DTAC polar headgroups in the ethylene oxide region of C12E6 is reported. These results provide an explanation at the molecular level of the different thermodynamical behavior found for mixed micelles composed of anionic-cationic, anionic-nonionic and cationic-nonionic surfactants.
Referência(s)