Intramolecular and intermolecular ion-dipole interactions in sodium lauryl ether sulfates (SLES) self-aggregation and mixed micellization with Triton X-100

被引:53
作者
Aoudia, Mohamed [1 ]
Al-Maamari, Thurayia [1 ]
Al-Salmi, Fathiya [1 ]
机构
[1] Sultan Qaboos Univ, Coll Sci, Muscat 123, Oman
关键词
Mixed micellization; Ion-dipole interaction; Intramolecular and intermolecular interaction; Critical micelle concentration; Micelle ionization degree; SURFACTANTS; BINDING;
D O I
10.1016/j.colsurfa.2008.10.026
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
Micellization of a series of sodium lauryl ether sulfate (SLES), C12H25(OCH2CH2)(x)OSO3Na, where x = 1 (CS130), 2 (CS230), and 3 (CS330) and their interaction with Triton X-100 in aqueous media were investigated by fluorescence quenching of (Ru(bipy)(3)(2+), 2Cl(-)) by 9-methyl anthracene, conductivity, and surface tension measurements at room temperature. A similar critical micelle concentration (CIVIC) value of 0.80 mM was found for the three ethoxylated surfactants, well below the CMC of sodium dodecyl sulfate (SDS) (8.2 mM), although the micelle ionization degree of SLES micelles were significantly higher (beta(ion) = 0.70) compared to the reported value in SDS micelles (beta(ion) = 0.18). This unexpected result was attributed to intramolecular and intermolecular attractive ion-dipole interactions between the sulfate ion (SO4-) and the O -> CH2 dipole of the oxyethylene (OE) group in SLES micelles. Also, the observed invariance of the CIVIC with the degree of ethoxylation was attributed to the fact that this ion-dipole interaction is effective only with the OE group linked to SO4- (intramolecular attractive interaction) and the sulfate group of a given surfactant in SLES micelles with the OE group adjacent to the sulfate group of a nearby surfactant (intermolecular attractive interaction). Changes in CMCs with the composition of the mixture of SLES (CS130, CS230, and CS330) and Triton X-100 so determined were analyzed by applying Rubingh's regular solution theory to obtain a similar interaction parameter beta(M) = -1.39, lower than the well-known corresponding interaction parameter in SDS/Triton X-100 reported in the literature (beta(M) = -3.80). This difference in surfactant-surfactant interaction in the two mixed systems was attributed to the intramolecular and intermolecular ion-dipole attractive interactions in single SLES micelles, whereas such interactions are not occurring in SIDS single micelles. This will be reflected by a relatively stronger self-repulsion between the sulfate groups in SDS micelles. In mixed micelles, the intramolecular ion-dipole attraction in SLES surfactants may have the dominant factor in the overall interactions between SLES surfactants and Triton X-100. Consequently, this may be reflected by a lower beta(M) as determined from our results. Interestingly, the decrease of the CMCs for SLES/Triton X-100 systems was also independent of the degree of ethoxylation, suggesting that both intramolectllar and intermolecular ion-dipole interaction in mixed micelles involves only the first OE group linked to the sulfate moiety. (C) 2008 Elsevier B.V. All rights reserved.
引用
收藏
页码:55 / 61
页数:7
相关论文
共 20 条
[1]  
Ahmad A, 2007, J OIL PALM RES, V19, P332
[2]  
[Anonymous], 1986, ACS SYM SER
[3]  
AOUDIA M, 2006, J SURFACTANTS DETERG, V9, P278
[4]  
DHARMESH V, 2003, TENSIDE SURFACT DET, V40, P5
[5]  
Fendler J.H., 1975, CATALYSIS MICELLAR M
[6]  
GHANDI H, 2001, J SURFACTANTS DETERG, V4, P359
[7]   STATIC AND DYNAMIC PROPERTIES OF SODIUM PARA-(1-PROPYLNONYL)BENZENESULFONATE MICELLES [J].
LIANOS, P ;
LANG, J .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 1983, 96 (01) :222-228
[8]   EFFECT OF BINDING OF CATIONS TO POLYETHYLENE-GLYCOL ON ITS INTERACTIONS WITH SODIUM DODECYL-SULFATE [J].
MALTESH, C ;
SOMASUNDARAN, P .
LANGMUIR, 1992, 8 (08) :1926-1930
[9]   Solubilization of naphthalene and pyrene by sodium dodecyl sulfate (SDS) and polyoxyethylenesorbitan monooleate (Tween 80) mixed micelles [J].
Mohamed, Aoudia ;
Mahfoodh, Al-Shaaili M. .
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 2006, 287 (1-3) :44-50
[10]  
MYERS D, 1996, SURFACTANT SCI TECHN