Influence of the molecular structure on the aggregation of imidazolium ionic liquids in aqueous solutions

Modaressi, Ali; Sifaoui, Hocine; Mielcarz, M.; Domańska, Urszula; Rogalski, Marek

doi:10.1016/j.colsurfa.2007.02.020

Cited by 148 publications

(113 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We did not take the work of Modaressi et al [42] into account because their measurements, especially for [C 10 MIm]Cl and [C 12 MIm]Br, deviate strongly from those of all other authors. Their methodology was unclear and the determination of the breakpoint that the authors describe is questionable.…”

Section: 6contrasting

confidence: 46%

Predicting the Critical Micelle Concentrations of Aqueous Solutions of Ionic Liquids and Other Ionic Surfactants

Preiss

Jungnickel

Thöming

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

Some ionic liquids (ILs) are structurally analogous to surfactants, especially those that consist of a combination of organic and inorganic ions. The critical micelle concentration (CMC) is a basic parameter of surface chemistry and colloid science. A significant amount of research has already been carried out to determine the CMCs of ILs. However, because of the many varied cation/anion combinations, it is a daunting task to measure the CMCs of all possible ILs. Herein we suggest a general rule for predicting the CMCs of ionic surfactants in water based on data from COSMO-RS calculations. In accordance with the Stauff-Klevens rule, the molecular volume (V(m)) is sufficient to describe similar homologous series of cationic surfactants such as imidazolium- and ammonium-based ionic liquids with varying side-chain lengths. However, to also include anionic surfactants like Na[C(n)SO(4)] in a more general correlation, V(m) has to be exchanged by the cubed molecular radius (r3(m)) and the molecular surface has to be used as an additional descriptor. Furthermore, to describe double amphiphilic compounds like [C(4)MIm][C(8)SO(4)], the enthalpies of mixtures calculated by COSMO-RS have to be taken into account. The resulting equation had allowed us to predict the CMCs of all of the 36 tested surfactants with an error similar to or smaller than the usual experimental errors (18 different cations, 10 different anions: root mean squared error (rmse)=0.191 logarithmic units; R(2)=0.994). We discuss the factors governing micelle formation on the basis of our calculations and show that the structure of our equation can be related to Gibbs' theory of crystallization.

show abstract

Section: 6contrasting

confidence: 46%

Predicting the Critical Micelle Concentrations of Aqueous Solutions of Ionic Liquids and Other Ionic Surfactants

Preiss

Jungnickel

Thöming

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…As has been described in a recent study, 37 some imidazolium ionic liquids (even the ones with a relatively shorter alkyl chain of no10) can show a cationic surfactant-like behavior in aqueous solutions; however, if the heteropolar bond of the ion pair is too strong, that is, the dissociation is restrained, the surface activity is weak. The salt [C6Mim][Br] seems to indicate, rather significantly, such a surfactant nature in the present ternary system.…”

Section: Lcst-type Phase-separation Behaviormentioning

confidence: 95%

“…Thereupon, the degree of ionic dissociation of the salt would be generally lowered, and, instead, a self-association nature of the salt to form an aggregate could be pronounced; 37 then, the aggregate may be stabilized by water molecules as a bridge being able to form hydrogen bond with the anionic moieties of two salts close to each other. 40 This implies a decrease in the number of the water ingredient to hydrate the hydrophobic surface of mesogenic HPC molecules, relative to the hydration condition in the corresponding HPC/water composition free of any salt.…”

Section: Lcst-type Phase-separation Behaviormentioning

confidence: 99%

Addition effects of imidazolium salts on mesophase structure and optical properties of concentrated hydroxypropyl cellulose aqueous solutions

Chiba

Ito

Nishio

2010

Polym J

View full text Add to dashboard Cite

Addition effects of N-alkyl-substituted methylimidazolium salts ([CnMim][X]) on the mesophase structure and lower critical solution temperature (LCST)-type phase-separation behavior of concentrated hydroxypropyl cellulose (HPC) aqueous solutions were investigated mainly by spectrophotometry. In the cholesteric mesophase formation, at concentrations of more than 50 wt% HPC, helical pitch (P) was confirmed to shift upward according to the chaotropic strength of X -, for example, in a manner satisfying the order of Cl À oBr À oNO 3 À oI À . Organocations generally elevated P relative to the nonionic reference, the effectiveness being pronounced in the order ofWith regard to LCST behavior, imidazolium additives raised the cloud point (T c ) in the isotropic solutions of p40 wt% HPC, whereas the T c value of mesomorphic solutions was prone to be lowered by the addition. Discussion of these observations took into consideration the differences in the N-alkyl structure and amphiphilic nature between cationic imidazolium varieties, as well as the difference in the chaotropic strength between the counter anions. It was also exemplified preliminarily that this kind of salt-containing lyotropic system of HPC exercised an electro-optical function when coupled with an electric circuit.

show abstract

“…El Seoud et al [8] first termed such amphiphilic ILs as surface active ILs (SAILs). Several researchers studied the aggregation and micellization of ILs in aqueous solution [8][9][10][11][12]. Baker et al [13] synthesized and evaluated micellar properties of a new class of N-alkyl-N-methylpyrrolidinium ILs.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and evaluation of new imidazolium‐based aromatic ether functionalized cationic mono and gemini surfactants

Sadula

Reddy

Kanjilal

2011

Eur. J. Lipid Sci. Technol.

View full text Add to dashboard Cite

Synthesis of a novel series of imidazolium-based surfactants, [(ROArCH 2 MIm)Br] with aromatic ether functionalized hydrophobic tail of varying chain lengths and also their gemini counterparts were conducted in the present work. Synthesis involves initial conversion of 4-hydroxy benzoic acid to its methyl ester followed by its O-alkylation with long chain fatty alcohols, which was subsequently reduced and brominated to get 4-alkyloxy benzyl bromide. For the synthesis of monocationic surfactant, 4-alkyloxy benzyl bromide is quaternized with N-methylimidazole. Gemini surfactants are synthesized by initial coupling of imidazole to 4-alkyloxy benzyl bromide followed by its quaternization with dibromoalkane. The surface properties of all the synthesized surfactants were determined using surface tensiometry. Within the same homologous series, expected decrease in critical micelle concentration (cmc) with the increase in hydrophobicity was observed for shorter chain homologs. However, the deviation in cmc value from regularity was observed when the number of carbon atoms in the hydrophobic chain exceeded a certain number. The cmc values of the geminis were found to be remarkably low compared to their monomeric counterparts.

show abstract

Influence of the molecular structure on the aggregation of imidazolium ionic liquids in aqueous solutions

Cited by 148 publications

References 21 publications

Predicting the Critical Micelle Concentrations of Aqueous Solutions of Ionic Liquids and Other Ionic Surfactants

Predicting the Critical Micelle Concentrations of Aqueous Solutions of Ionic Liquids and Other Ionic Surfactants

Addition effects of imidazolium salts on mesophase structure and optical properties of concentrated hydroxypropyl cellulose aqueous solutions

Synthesis and evaluation of new imidazolium‐based aromatic ether functionalized cationic mono and gemini surfactants

Contact Info

Product

Resources

About