Decrease In Critical Micelle Concentration Research Articles

Interactions of new 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based surface active ionic liquids with amitriptyline hydrochloride: Micellization and interfacial studies

A new series of cationic surface active ionic liquids (SAILs) based on DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) was synthesized through the quaternization of DBU by alkyl bromides. The SAILs viz. DBU-C12 (8-N-dodecyl-1,8-diazabicyclo[5.4.0]undec-7-en-8-ium bromide), DBU-C14 (8-N-tetradecyl-1,8-diazabicyclo[5.4.0]undec-7-en-8-ium bromide) and DBU-C16 (8-N-hexadecyl-1,8-diazabicyclo[5.4.0]undec-7-en-8-ium bromide) were obtained and their aggregation behaviour was examined by surface tension and conductivity measurements. The SAILs investigated displayed better surface activity than the imidazolium based SAILs (CnmimBr) as well as the conventional cationic surfactants, alkyltrimethylammonium bromides (CnTAB). They also showed a decrease in critical micelle concentration (cmc) values with an increase in the alkyl chain length. Further, their interactions with amphiphilic drug, amitriptyline hydrochloride (AMT) have also been studied by employing the theoretical models proposed by Rubingh, Motomura and Gibbs. The micellar interaction parameter (βm) is negative for most of the mole fractions of AMT (αAMT) in DBU-C14/DBU-C16+AMT systems, indicating attractive interactions. The interfacial parameters such as surface tension reduction efficiency (pC20), effectiveness of surface tension reduction (πcmc), maximum surface excess concentration at the air-water interface (Γmax) and minimum area per surfactant molecule (Amin) were also evaluated for the mixed systems of DBU based SAILs with AMT. The standard Gibbs free energy of micellization (ΔG°m) and the standard free energy of adsorption at the air/water interface (ΔG°ad) for these systems were found to be negative, confirming the feasibility of these drug–SAIL interactions.

Novel biomimetic systems based on polyethylene glycols and amphiphilic phosphonium salt. Self-organization and solubilization of hydrophobic guest

The solution behavior of single and binary systems based on biorelevant building blocks, i.e., polyethylene glycol (PEG) of different molecular weight, and a cationic surfactant, cetyltriphenylphosphonium bromide (TPPB), has been studied. Tensiometry data for PEG–water solutions provide critical aggregation concentrations which decrease with an increase of molecular weight of the polymer. Large particles of ⩾200nm occur in the PEG-1000 solution along with the smaller ones, while in the PEG-400 and PEG-20000 samples only populations coinciding with the size of the polymer coils are found. The dye solubilization study reveals that some hydrophobic domains occur in the PEG solution. The binary PEG-TPPB systems demonstrate a synergetic behavior, i.e. a decrease in critical micelle concentration and much higher solubilization power as compared to single TPPB micelles. The data obtained reveal that PEG-TPPB assemblies present soft nanocontainers, which (i) are composed of biorelevant components; (ii) are formed at low concentrations; (iii) are characterized by nanoscale dimension; (iv) exhibit high binding capacity toward water insoluble guest. Based on these features they may be considered as candidates for the drug delivery formulations.

Ionic liquid-induced changes in the properties of aqueous sodium dodecyl sulfate solution: effect of acidic/basic functional groups

The effects of ionic liquids 1-(2-aminoethyl)-3-methylimidazolium chloride ([MimAE]Cl), 1-carboxylmethyl-3-methylimidazolium chloride ([MimCM]Cl), 1-(2-hydroxylethyl)-3-methylimidazolium chloride ([MimHE]Cl), and 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) on the physicochemical properties of aqueous sodium dodecyl sulfate (SDS) solutions were studied. Compared with [Emim]Cl, the presence of amino group can further facilitate the micellization of SDS, while the opposite result is observed as carboxyl group is imparted. No obvious changes in critical micelle concentration (CMC) and $$ {\gamma_{\mathrm{CMC}}} $$ values are induced by the neutral hydroxyl group. Only the addition of [MimAE]Cl drastically increases the micellar size. Significant decrease in CMC and increase in micellar size were observed with decreasing pH of [MimAE]Cl solution. The increase in pH of [MimCM]Cl solution results in a slight increase in CMC and decrease in micellar size. 1H NMR spectra revealed the amino groups are adsorbed at the micellar surface, while the carboxyl groups/carboxylate ions and hydroxyl groups tend to point towards bulk water.

Physicochemical characterizations of amphiphilic block copolymers with different MWs and micelles for development of anticancer drug nanocarriers

Biocompatible polymers have been of considerable interest in developing drug delivery systems (DDSs). However, physicochemical characterizations of the polymers and DDSs had been limited because of the difficulty in obtaining the same synthesized copolymers and achieving a similar drug loading ability with the differing properties of the drugs. Therefore, a correlational study of the relationships between copolymers and DDSs was required to estimate the properties of the DDSs and to develop optimal systems of delivery depending on the drug. In this study, we presented several relationship correlation equations of physicochemical properties and copolymers according to their molecular weights (MWs) using amphiphilic block copolymers composed of poly(L-lactide)-block-methoxy-poly(ethylene glycol) (PLA-b-mPEG). The PLA-b-mPEG was characterized by nuclear magnetic resonance and gel permeation chromatography, and the critical micelle concentration (CMC), sizes, and drug loading capacity (DLC) of the self-assembling micelles from the copolymers with different MWs were all measured. The increase in MW of the PLA led to a decrease in CMC and DLC with an increase of the particle sizes. The relationship between the MW of the PLA and the physicochemical properties of the micelles demonstrated a good correlation, which provides excellent information for the use in the development of tailor-made DDSs based on copolymers pursuing optimal particle size, DLC, CMC, and so on. Open image in new window

Aqueous Solution Behavior of Cationic Surfactant Modulated by the Presence of Glycols and Their Ethers

Abstract The effect of ethylene glycol (EG), diethylene glycol (DEG) and their monoalkyl (C1–C6) ethers (cellosolves and carbitols) and dimethyl ethers (glymes and diglymes) on the micellar behavior of a cationic surfactant tetradecyltrimethylammonium bromide (TTAB) in aqueous solution was examined from electrical conductivity measurements. The effect of these additives on critical micelle concentration (CMC) and degree of counter ion dissociation (α) is evaluated. While both EG, DEG, their monomethyl/monoethyl ethers and dimethyl ethers increased CMC and α, for monobutyl and monohexyl ethers a decrease in CMC was noticed at studied concentration. For all ethers, the α values increased with concentration. NOESY experiments confirmed the location of glycol ethers in micellar solution. The results are discussed in terms of effect of ethers on water structure and solvent properties.

Effects of molecular architectures and solvophobic additives on the aggregative properties of polymeric surfactants

The aggregative behavior of the polymeric surfactants with various molecular architectures in dilute solutions is studied by dissipative particle dynamics. The effects of the solvophobic/solvophilic length, polymeric architecture (linear, star, dendritic, and cyclic type), chain rigidity, and solvophobic additives on the critical micelle concentration (CMC) and the aggregative patterns are systematically investigated. It is found that molecular architectures have a noteworthy impact on the aggregative properties. For linear diblock copolymers, the CMC declines with increasing solvophobic length but rises with increasing solvophilic length. Nonetheless, the solvophobic group has comparatively greater influence on the CMC. Imposition of the star, dendritic, or cyclic structures onto the solvophobic or solvophilic parts of the polymeric surfactant leads to an increase in the CMC. On the contrary, polymers imposed with the greater degree of the rigidity on the solvophobic or solvophilic block have lower CMC. The addition of solvophobic additives results in a decrease of CMC as well. The effects of the concentration and length of the additives on the aggregative behaviors of polymer surfactants were investigated. Interesting supramolecular structures such as caterpillar and worm-like micelles were observed.

Cationic Micelles Modulated in the Presence of α,ω‐Alkanediols: A SANS, NMR and Conductometric Study

AbstractThe solution behavior of a typical cationic surfactant, tetradecyltrimethylammonium bromide, in mixed solvent systems composed of water and varying concentrations of α,ω‐alkanediols; 1,2‐ethanediol (ED), 1,4‐butanediol (BD), 1,6‐hexanediol (HD) and 1,8‐octanediol (OD) was examined via electrical conductance measurements, 13C‐NMR spectroscopy and small angle neutron scattering (SANS) measurements. The critical micelle concentration (CMC) values and degree of counterion dissociation (α) indicate that both ED and BD oppose micellization, whereas HD and OD enhance micelle formation. Changes in the 13C‐NMR chemical shifts (∆δ values) reveal that the short chain diols reside almost exclusively in the bulk phase and hence, affect the formation of micelles by altering the solvent properties in the bulk of the solution, whereas HD and OD partition between the pseudomicellar phase and the bulk phase. SANS studies indicated that both the micellar size and aggregation number (Nagg) decrease in the presence of all diols. ED and BD behave like cosolvents and increase the α and CMC values and decrease Nagg. We note that the effect of HD and OD on the properties of the micelles is concentration dependent; at low concentrations, these diols interact with the micelles and behave as cosurfactants (as evidenced by the trends in the micellar properties), while at higher concentrations, they enhance the surfactant solubility and behave as a cosolvent.

Micellar Properties and Related Thermodynamic Parameters of Aqueous Anionic Surfactants in the Presence of Monohydric Alcohols

The effect of monohydric alcohols, (C7–C10), on the micellar behavior of anionic surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS), was investigated using experimentally measured densities, ρ, speeds of sound, u, and specific conductivities, κ, at various temperatures and atmospheric pressure. A number of thermodynamic parameters, like apparent molar volumes, Φv, partial molar volumes, Φov, isentropic compressibility, κs, and various thermodynamic parameters of micellization were calculated to elucidate the interactions prevailing in the studied aqueous surfactant–alcohol systems. The decrease in critical micelle concentration (cmc) on addition of an additive may be seen in terms of establishment of additional hydrophobic interactions between the hydrophobic part of the surfactant and additive molecules. It can be seen that ΔG°m < 0 is weakly dependent on alcohol concentrations in aqueous surfactant solutions. Further, 1H and 13C NMR chemical shift measurements in micelle solutions containing above-mentioned alcohols have also been carried out. From 1H and 13C NMR spectra, it was concluded that the site for preferential solubilization of alcohol is close to the headgroup of the micelle. The trend observed in carbon chemical shifts may be attributed to the chain length of the added alcohols due to the strong ion–dipole interaction between the negatively charged SDS headgroup and the hydroxyl group of the alcohol.

Aggregation of antihistamines in aqueous solution. The effect of electrolyte on the micellar properties of some diphenylmethane derivatives

The effect of sodium chloride on the micellar properties of the antihistamines, dephenhydramine hydrochloride, bromodiphenhydramine hydrochloride, chlorcyclizine hydrochloride and diphenylpyraline hydrochloride in aqueous solution has been investigated by light scattering and viscometric methods. The drugs behaved as typical ionic surfactants showing an increase in aggregation number and decrease in critical micelle concentration as the electrolyte concentration was increased over the range 0.05 to 0.154 mol kg-minus1. A linear relation between log critical micelle concentration and log counterion concentration was established, from which values of the degree of ionization and the free energy of micellization were calculated. The intrinsic viscosity was decreased by the addition of electrolyte and this has been attributed to a decrease in micellar hydration due to a removal of hydrogen-bonded water.

Partial molal volumes of some non-ionic detergents in monomeric and micellar form.

Abstract Partial molal volumes of five synthetic non-ionic detergents have been measured above and below their critical micellar concentrations. The increases in volume on micellisation are discussed in terms of changes in hydration and hydrophobic bonding. The change in partial molal volume at the critical micellar concentration decreased with temperature. At 20° increases of 5, 9 and 17 ml mole−1 were obtained for the n-butyl, n-hexyl and n-octyl hexaoxyethylene glycol ethers respectively. For comparison with the alkyl ethers, the partial molal volume of hexaoxyethylene glycol was determined at four temperatures. The utility of density measurements for the determination of the critical micelle concentration of these non-ionic detergents depended on the temperature of the system; at higher temperatures the change in slope of density-concentration plots at the critical micelle concentration decreases and sometimes is not detectable.

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

Synthesis of a novel series of imidazolium-based surfactants, [(ROArCH2MIm)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.

Micellization and Interfacial Behaviour of Amitriptyline-Nonionic Surfactant Systems in Aqueous Medium

Abstract By means of surface tension measurement (ring detachment method) mixed micellization and mixed adsorbed film formation were studied between an amphiphilic drug (amitriptyline hydrochloride – AMT) and nonionic surfactants (Tritons and Tweens) at different mole fractions. From the equilibrium surface tension measurements critical micelle concentration (CMC), maximum surface excess (Γmax) and minimum area per surfactant molecule at the air/solution interface (Amin) were obtained. The theories of Rosen, Rubingh and Maeda were applied to analyse the results. Different thermodynamic parameters, viz. free energy of micellization (ΔGo m), standard Gibbs energy of adsorption (ΔGo ads), and minimum energy of surface (Gmin) were evaluated. In the mixed micelles, presence of nonionic surfactants between the head groups of drug molecules decreases the repulsion among head groups. As a result, the CMC and Amin decrease while Γmax increases. Interaction parameters of micelles (βm) and monolayer (βs) indicate that the drug surfactant systems show better interaction at the interface than in micelles.

Synthesis and morphology transformation of amphiphilic diblock polyurethane copolymers in aqueous solution

Amphiphilic block copolymers possess both hydrophobic and hydrophilic properties and can form versatile micellar structures in aqueous solution. The aim of the research presented was to prepare a series of non-ionic amphiphilic diblock polyurethane copolymers (PUn) based on isophorone diisocyanate, monoallyl-end-capped poly(ethylene oxide) and poly(propylene oxide) (PPO), followed by an investigation of their micellization properties and morphology transformation in aqueous solution. The PUn samples were synthesized by condensation polymerization. These polyurethanes exhibit surface tension as low as 33.7–37.0 mN m−1. There is an obvious decrease in critical micelle concentration as the hydrophobic PPO molecular weight increases. According to transmission electron microscopy, the morphology of aggregates of the copolymers can be tuned by varying the concentration in aqueous solution rather than organic solvent. For example, for PU7, large compound micelles are produced instead of vesicles. For PU17, the concentration can be used to control the size and thickness of vesicles. Vesicle size increases from 60 to 500 nm and vesicle thickness from 40 to 60 nm with concentration ranging from 0.003 to 0.03 wt%. The study shows that the copolymers in aqueous solution have excellent surface activities. In addition, they can self-assemble into large compound micelles or vesicles at certain concentrations. Moreover, the synthesis method described allows one to obtain a desired morphology of aggregates by adjusting the composition of hydrophilic and hydrophobic segments, which provides a novel and simple way to obtain particles on the nanometer scale. Copyright © 2010 Society of Chemical Industry

Formation and Growth of Micelles in Dilute Aqueous CTAB Solutions in the Presence of NaNO3 and NaClO3

AbstractSelf‐assembly of cetyltrimethylammonium bromide (CTAB) in aqueous solution, in the presence of two inorganic salts viz, NaNO3 and NaClO3 was investigated by steady‐state fluorescence, electrical conductance, surface tension, viscosity, dynamic light scattering (DLS) and cryogenic transmission microscopy (cryo‐TEM). The counterions located at short enough distances to CTA+ micellar surface experience a very strong electrostatic attraction and thus become condensed. This counterion condensation plays a significant role in deciding the effective charge on the micelle, their screening interaction and structural transition of the micelles. In the present work, the probable mechanism of the salts' action in aqueous solution of CTAB is explained. The critical micelle concentration (CMC), area per molecule (Å2), micelle hydrodynamic diameter (Dh), and aggregation number (Nagg) of CTAB micelles in the absence and presence of the salts are reported. The addition of both salts followed the lyotropic series and showed a remarkable decrease in CMC. A detailed investigation of the structural transitions from spherical to rod or even to entangled wormlike structures is presented from cryoTEM.

Synthesis and evaluation of micellar properties and antimicrobial activities of imidazole‐based surfactants

AbstractThe synthesis of two types of imidazole‐based surfactants, [(ROCOCH2MIm)Br] and [(RNHCOCH2MIm)Br], of varying chain lengths (C10, C12 and C16), was conducted in the present work. The synthesis involves an initial reaction of bromoacetic acid with fatty alcohols or fatty amines, followed by quaternization with N‐methyl imidazole. The micellar properties of all the synthesized compounds were determined using surface tensiometry and compared with [(RMIm)Br], a well‐studied alkyl‐substituted imidazole‐based surfactant. Within the same homologous series, a decrease in critical micelle concentration (cmc) was observed with increasing alkyl chain length in all three types of cationic surfactants. Introduction of an ester [(ROCOCH2MIm)Br] or an amide group [(RNHCOCH2MIm)Br] in the alkyl chain lowers the cmc when compared to a cationic surfactant without functional group, [(RMIm)Br]. The synthesized surfactants were also assayed for antimicrobial activities and found to possess good activities against selected strains.

A Monte Carlo study of crowding effects on the self-assembly of amphiphilic molecules

In this work, lattice Monte Carlo was used to study the effects of crowding on the self-assembly of surfactants. Simulation results show that crowding strongly shifts the critical micelle concentration (CMC) of surfactants from the bulk value. Two effects originated from crowding are found to govern the CMC shift: one is the depletion effect by crowding agents and the other is the available volume for micelle formation. The depletion effects inevitably result in the enrichment of surfactants in crowding-free regions and cause the decrease in CMC. On the other hand, the appearance of crowding agents decreases the available volume for micelle formation, which reduces the conformational entropy and impedes the micelle formation. Three factors, including the radius of crowding agents, the arrangement of crowding agents, and the volume fraction of crowding agents, are considered in this work to study the crowding effects. The trends of CMC shifts are interpreted from the competition between the depletion effects and the available volume for micelle formation.

Studies on CMC and thermodynamic function of anionic surfactants in DMA/long-chain alcohol systems using microcalorimetric method

The critical micelle concentration (CMC) and the thermodynamic function of the anionic surfactant, sodium laurate (SLA) and sodium dodecyl sulfate (SDS) in the N,N-dimethyl acetamide (DMA)/long-chain alcohol systems were studied using titration microcalorimetric method. The power-time curves of SLA and SDS in the presence of a long-chain alcohol (n-heptanol, n-octanol, n-nonanol, n-decanol) in the DMA medium were determined. Then, from the curves, the critical micelle concentration (CMC) and the thermodynamic standard formation functions (ΔH ϑ m, ΔG ϑ m and ΔS ϑ m) were obtained through thermodynamic theories. The relationships between temperature, alcohol’s carbon number, concentration and thermodynamic properties were discussed. For SLA or SDS in a DMA solution, under the same concentration of alcohol, the values of CMC, ΔH ϑ m and ΔS ϑ m increase, while the value of ΔG ϑ m decrease with the increase of temperature. Under the same condition of identical temperature and alcohol concentration, the values of CMC, ΔH ϑ m, ΔG ϑ m and ΔS ϑ m decrease with the increase of the alcohol’s carbon number. In the presence of the same kind of alcohol, the values of CMC and ΔG ϑ m increase, but the values of ΔH ϑ m and ΔS ϑ m decrease with the concentration increases in alcohol series at the same temperature.

Physicochemical characterization, in vitro, and in vivo evaluation of indomethacin‐loaded nanocarriers self‐assembled by amphiphilic polyphosphazene

Copolymeric nanocarriers assembled by amphiphilic polyphosphazene bearing poly(N-isopropylacrylamide) (PNIPAAm) and ethyl glycinate (EtGly) as substitutes, were investigated as drug vehicles for indomethacin (IND). The physicochemical characteristics of the novel nanocontainers were studied, including lower critical solution temperature (LCST), critical micelle concentration (CMC) and drug loading capacity. LCST measurements revealed that copolymer is more sensitive to the introduction of salts into aqueous solution compared with homopolymer. A significant decrease in CMC was observed when the temperature increased above LCST. As evidenced by transmission electron microscopy (TEM) measurement, morphological transformation from multicompartment into spherical nanoparticles was observed when nanocarriers with higher IND content were concerned. In vitro release tests suggested that IND-loaded nanocontainers exhibited pH dependent release profiles. In vivo pharmacokinetic study after subcutaneous administration provided a relatively sustained release behavior. Additionally, compared with free drug solution at the same dose, IND concentration in rat plasma showed a prolonged retention in experimental group treated with IND-loaded micelles. In vivo pharmacodynamic study based on both carrageenan-induced acute and complete Freund's adjuvant (CFA) induced adjuvant-arthritis models indicated that sustained therapeutic efficacy could be achieved through intraarticular injection of IND-loaded micelles. Most importantly, local delivery of IND can avoid the severe gastrointestinal stimulation, which is frequently associated with oral administration.

Concentration-Dependent Dual Behavior of Hydrophilic Ionic Liquid in Changing Properties of Aqueous Sodium Dodecyl Sulfate

Modifying physicochemical properties of aqueous surfactant solutions in favorable fashion by addition of environmentally benign room-temperature ionic liquids (ILs) has enormous future potential. Due to its unusual properties, an IL may demonstrate a unique role in altering the properties of aqueous surfactant solutions. Changes in the properties of aqueous sodium dodecyl sulfate (SDS), an anionic surfactant, upon addition of a common and popular "hydrophilic" ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] are presented. Addition of low concentrations of [bmim][BF4] (i.e., <or=2 wt %) to aqueous SDS results in a decrease in critical micelle concentration (cmc) as well as an increase in aggregation number (N(agg)) and average micellar size. An increase in dipolarity and a decrease in microfluidity of the micellar phase is reported by solvatochromic fluorescence probes pyrene and 1,3-bis-(1-pyrenyl)propane as up to 2 wt % [bmim][BF4] is added to aqueous SDS. The IL is observed to behave similarly to common electrolytes in the concentration range 0 < [bmim][BF4] <or= 2 wt %. A further increase in [bmim][BF4] concentration to 30 wt % results in an increase in cmc which is accompanied by a decrease in N(agg) and average micellar size. Change in the microfluidity of the micellar phase is observed to become insignificant in this concentration range. Evidence of the presence of micellar aggregates at such high concentration of [bmim][BF4] is furnished by dynamic light scattering. The role of an IL in altering the properties of aqueous SDS in the range 2 wt % < [bmim][BF4] <or=30 wt % is similar to those of polar cosolvents. The concentration-dependent dual role of the IL [bmim][BF4] in altering physicochemical properties of aqueous SDS is demonstrated.

Modulating properties of aqueous sodium dodecyl sulfate by adding hydrophobic ionic liquid

Altering and modifying important physicochemical properties of aqueous surfactant solutions is highly desirable as far as potential applications of such systems are concerned. Changes in the properties of aqueous solutions of a common anionic surfactant sodium dodecyl sulfate (SDS) are assessed in the presence of a common and popular ‘hydrophobic’ ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF 6). Upon addition of up to ∼ 0.10 wt % bmimPF 6, a dramatic decrease in critical micelle concentration (cmc) is accompanied by an increase in the degree of counterion dissociation ( α) and micellar aggregation number ( N agg ) indicating micellar growth. However, in the range 0.10 wt% ⩽ bmimPF 6 ⩽ 2.00 wt%, relatively gradual decrease in α and N agg is observed along with no change in cmc. Significantly decreased microfluidity of the aqueous SDS solutions on addition of bmimPF 6 is indicated by a fluorescence microviscosity probe 1,3- bis-(1-pyrenyl)propane which suggests partitioning of bmimPF 6 into the SDS micellar phase. Behavior of solvatochromic fluorescence probes, pyrene, pyrene-1-carboxaldehyde, and 2-( p-toluidino)naphthalene-6-sulfonate, confirms interaction, and possible complexation, between IL bmimPF 6 and anionic micellar surface. Increased solubility of bmimPF 6 with increasing SDS concentration further confirms SDS-bmimPF 6 interactions. Presence of strong electrostatic attraction between bmim + and anionic micellar surface is proposed to be the most dominant reason for these observations. All-in-all, unique role of a hydrophobic ionic liquid bmimPF 6 in modifying the properties of aqueous anionic sodium dodecyl sulfate is demonstrated.