Micellar Behavior Research Articles

Effect of chain length and counter-ion on interaction study of mixed micellar system of isoquinoline-based surface active ionic liquid and cationic surfactants in aqueous medium

In the present study, we have investigated the effect of nature of surfactant, chain length and counter-ion on the mixed micellization behaviour ofvarious cationic surfactants, tetradecyltrimethylammonium bromide (TTAB), dodecyltrimethylammonium chloride (DTAC) and cationic gemini surfactant, bis(tetradecyldimethylammonium)hexane dibromide(C14-6-C14,2Br) with surface active ionic liquid (SAIL) tetradecylisoquinolinium bromide [C14iQuin][Br]. The interactions and mixed micellar behaviour of cationic surfactants and SAIL in aqueous medium have been studied by employing conductometry measurements and 1H NMR technique. The critical micelle concentration (cmc) and various thermodynamic parameters like standard Gibbs free energy of micellization (ΔGm0), change in standard enthalpy (ΔHm0) and entropy of micellization (ΔSm0) have been calculated from conductometry measurements. Mixed micellar parameters such as ideal cmc (cmc*), micellar mole fraction (X1m), micellar interaction parameter (βm) and activity coefficients, (f1 and f2) have been evaluated by applying Clint, Rubingh and Motomura theoretical models. Synergistic and non-ideal interactions have been found between SAIL and surfactants.

Elucidation of Interactions between l‐Ascorbic Acid and Mixed Micellar Aggregates of Catanionic {Sodium Dodecylsulfate + Cetyltrimethylammonium Bromide} Surfactants via Physicochemical and Spectroscopic Studies

AbstractSurfactant micelles mimic the microenvironment present in biological systems and can act as a medium for antioxidant studies. Moreover, the thermodynamic profile of micellization and spectroscopic studies provides very good information about interactions in these systems. Thus, the mixed micellar behavior of sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB) at varying mole fractions of SDS was studied in (0.01, 0.02, and 0.03) mol kg−1 ʟ‐ascorbic acid(aq) solutions with the aid of various techniques viz., conductivity, density and sound velocity, and spectroscopy. From the CMC values of the mixed surfactants, the degree of ionization (β) and thermodynamic parameters (, , and ) were evaluated at 298.15, 308.15, and 318.15 K. The UV absorption spectra were recorded in (1–3) × 10−4 mol kg−1 ʟ‐ascorbic acid(aq) solutions at various mole fractions of SDS. The proton (1H) NMR spectra of mixed (SDS + CTAB) surfactants were studied in (0.01–0.03) mol kg−1 ʟ‐ascorbic acid solutions. Hydrodynamic diameters (Dh) of mixed micellar aggregates were obtained from the dynamic light scattering (DLS) studies. The present studies suggest the predominance of ionic‐hydrophilic interactions between the ionic head groups {O‐SO3− or N+ (CH3)3} of surfactants and the polar (–OH, –C=O and –O–) sites of ʟ‐ascorbic acid.

Aggregation and organic phase splitting behavior of a synergic extractant system probed by dynamic light scattering spectroscopy

A synergic solution of N,N-di-n-octyl-2-hydroxyacetamide (DOHyA) and bis-(2-ethylhexyl)diglycolamic acid (HDEHDGA) in n-dodecane has been proposed for the single-cycle separation of Am(III) and Cm(III) from high-level nuclear waste containing chemically similar lanthanides in 3–4 M nitric acid medium. The reverse micellar aggregation behavior of the binary extractants in n-dodecane has been studied in the synergic extraction regime (>1 M nitric acid) by dynamic light scattering (DLS) spectroscopy. The results were compared with the individual extractants in n-dodecane. The aggregation of reverse micelles increased with increase in the loading of nitric acid and Nd(III) in the organic phase in all organic solutions. The organic phase underwent splitting into two phases, with the lighter one “diluent-rich” and the heavier one “aggregate rich” at a particular limiting value of Nd(III) and nitric acid loading in the organic phase. Accordingly, the limiting reverse micellar aggregate size in organic phase for third phase formation was determined, and it was found to increase with increase in the polarity of the ligand in organic phase. Studies with simulated nuclear waste revealed that the binary solution composed of (0.2 M DOHyA +0.1 M HDEHDGA)/n-DD would not undergo phase splitting as the aggregate size formed in organic phase was much lower than the limiting aggregate size of 15 nm for phase splitting in the present case.

Syntheses, surface activities and aggregation morphologies of a series of novel itaconic acid based asymmetrical gemini surfactants

A series of novel itaconic acid based asymmetrical gemini surfactants containing two long alkyl chains, two selfsame nonionic groups along with an anionic moieties covalently attached by an itaconic acid spacer group (polyoxyethylene laurinol ether sodium sulfoitaconate: PLSS-n) have been synthesized through esterification and sulfonation reaction using itaconic anhydride (IAn) and polyoxyethylene alkyl ethers. The chemical structures of the PLSS-n homologs were confirmed through FT-IR, 1H NMR spectra and elemental analysis (EA). And their physico-chemical properties in aqueous solutions were further investigated. The PLSS-n species have lower equilibrium surface tension (γCMC) and critical micelle concentration (CMC), lower Krafft points (Tk), good wettability and foaming properties. The γCMC and CMC values of PLSS-n are decreased with the increase of the temperature. The PLSS-n homologs exhibit high surface activities even at lower temperature. The PLSS-n homologs all exhibit smaller values of areas per molecule (Amin) and larger values of maximum excess surface concentration (Γmax). The rheological behaviors of the PLSS-n solutions show that only PLSS-3 shows shear thinning feature with the increasement of shear rate. The average diameters of the PLSS-n aggregations were studied by Dynamic light scattering (DLS) at 25 °C. Cryogenic transmission electron microscopy (cryo-TEM) results of the PLSS-n indicate that these gemini surfactants can form various micellar behaviors, which are affected by different combined factors. The Small angle X-ray scattering (SAXS) measurements provide evidence of the anisotropic lamellar structure.

Synthesis of Carbohydrate Derived Non-ionic Gemini Surfactants and Study of Their Micellar and Reverse Micellar Behavior - A Review

Gemini surfactants (gemini) are a distinct class of amphiphiles having more than one hydrophobic tail and hydrophilic head group connected via a spacer. These surfactants usually have better surface active properties than corresponding conventional surfactant of equal chain length. Depending upon the nature of charge on head group, these geminis may be cationic or anionic. If there is no charge on head group, the geminis are termed as non-ionic. Carbohydrate derived gemini surfactants carry sugar moiety linked with each of the conventional surfactants, which are further connected by spacer. The sugar moiety was found to enhance the aggregation tendencies. Moreover, due to the presence of sugar moiety, these surfactants are non-toxic and biodegradable. Due to chiral nature of sugar moiety, these surfactants can be used for chiral recognition of some chiral drugs in order to improve their aqueous solubility. Non-ionic surfactants are more important than ionic surfactants as in the latter case, due to repulsion among the same charged head group, aggregation does not take place readily. However, in case of non-ionic surfactants, the head group carries no charge, so there is no repulsion, thus micelle forms easily and at low concentration. The only repulsive forces among head groups are due to hydration shell formed by solvent molecules.

Startup steady shear flow from the Oldroyd 8-constant framework

One good way to explore fluid microstructure, experimentally, is to suddenly subject the fluid to a large steady shearing deformation and to then observe the evolving stress response. If the steady shear rate is high enough, the shear stress and also the normal stress differences can overshoot, and then they can even undershoot. We call such responses nonlinear and this experiment shear stress growth. This paper is devoted to providing exact analytical solutions for interpreting measured nonlinear shear stress growth responses. Specifically, we arrive at the exact solutions for the Oldroyd 8-constant constitutive framework. We test our exact solution against the measured behaviors of two wormlike micellar solutions. At high shear rates, these solutions overshoot in stress growth without subsequent undershoot. The micellar solutions present linear behavior at low shear rates; otherwise, their behavior is nonlinear. Our framework provides slightly early underpredictions of the overshoots at high shear rates. The effect of salt concentration on the nonlinear parameters is explored.

Micellar and rheological properties of some sodium deoxycholate-based poly(ester ether)urethane ionomer biomaterials in N,N-dimethylformamide solutions

In this work new sodium deoxycholate-based poly(ester ether)urethane ionomers are prepared. The micellar and rheological behaviour of these polyurethanes in N,N-dimethylformamide solutions are studied by means of transmission electron microscopy, dynamic light scattering, steady state fluorescence measurements and rheological oscillatory tests. For poly(ethylene oxide)- and poly(propylene oxide)-based polyurethanes spherical core-shell micellar morphology was obtained, whereas for pluronic-based polyurethanes micellar aggregate morphology was obtained. Increased values of critical micelle concentration were determined for the polyurethanes containing more solvophilic poly(ethylene oxide) segments as found for Pluronic block copolymer surfactants. It was found that the type of polyether macrodiol influences the micellar morphology and rheological behaviour. Viscosity of the polyurethane solutions is influenced by their concentration, micellar network, molecular weight and hard segment content of polyurethane. Shear thinning (pseudoplastic) behaviour of the polyurethane solutions was revealed. Gel-sol transitions and liquid-like behaviour were revealed by amplitude sweep tests. Gel-like behaviour and gel-sol transitions were revealed by frequency sweep tests.

Salt and phytochemical assisted modulation of self-assembly characteristics of Polysorbate-80 in aqueous medium

Polysorbate 80 is one of the most widely used solubilizing agents in food, cosmetic and pharmaceutical industries. Influences of different classes of solubilizates and additives on its self-assembly characteristics are however, not sufficiently understood yet. In this manuscript, we show how common water structure making salt NaCl, and lipophilic phytochemicals like curcumin and lavender oil help in modulating the structure of Polysorbate 80 micelles in aqueous medium. Our DLS, SANS and rheological studies show that NaCl induces sphere-to-rod growth of polysorbate 80 micelles at the room temperature. Micellar solubilizations of the phytochemicals, which were found to be facilitated with increase in temperature, induce only a marginal growth of the micelles up to the highest level of solubilization. Their presence however, helps in modulating the NaCl induced micellar growth behavior in the tween 80 solutions leading to observation of micelle-to-vesicle structural transition at 2% lavender oil concentration. The phytochemical solubilized micellar solutions could be converted to alginate based hydrogel beads and patches that can freely release micellar phytochemical in aqueous medium. Our results shed light on possible ways of modulating the solubilization behavior, self-assembly characteristics and rheological properties of aqueous system of polysorbate 80, which could be important for their applications.

Discrete and Discontinuous Increase in the Micellar Aggregation Number: Effects of the Alkyl Chain Length on Platonic Micelles.

Micelles with perfect monodispersity in terms of the aggregation number ( Nagg) have recently been discovered, whose values of Nagg interestingly always coincide with the vertex or face number of regular polyhedral structures (i.e., Platonic solids). Owing to the monodispersity of the micelles, named Platonic micelles, we could expect them to exhibit unprecedented aggregation behavior. In this study, the effects of alkyl chain length on micellar aggregation behavior were characterized using small-angle scattering techniques such as small-angle X-ray scattering and asymmetrical flow field-flow fractionation coupled with multi-angle light scattering, as well as analytical ultracentrifugation measurements. The Nagg of Platonic micelles discretely and discontinuously increased when increasing the alkyl chain length, which differs markedly from the findings for conventional micelles. This aggregation behavior could be reasonably explained by the relationship between the thermodynamic stability of the micelles and the coverage density defined by one of the unsolved mathematical problems: the Tammes problem.

Thermodynamic and spectroscopic studies on cationic surfactant tetradecyltrimethylammonium bromide in aqueous solution of trisubstituted ionic liquid 1, 2-dimethyl-3-octylimidazolium chloride at different temperatures

In this work, the effects on micellar behavior of long chain cationic surfactant tetradecyltrimethylammonium bromide (TTAB) upon the addition of trisubstituted ionic liquid (IL), 1, 2-dimethyl-3-octylimidazolium chloride [odmim][Cl] at temperatures, 298.15–318.15 K has been studied. Different techniques such as conductance, surface tension, fluorescence and 1H NMR have been employed to understand the interactional mechanisms. The values of critical micelle concentration (cmc) and various thermodynamic parameters have been calculated from conductivity measurements. The surface parameters like effectiveness of decrease in surface tension (Πcmc), minimum surface area occupied per surfactant monomer (Amin), maximum surface excess concentration (Γmax), and adsorption efficiency (pC20) have been evaluated by surface tension measurements. Micellar aggregation number (Nagg) has been determined by quenching of pyrene. Further to understand interactions in post micellar region, 1H NMR measurements have been performed. It has been observed that the lipophilicity of interacting ion modified the thermodynamic and aggregation properties of TTAB.

Interaction of methylparaben and propylparaben with P123/F127 mixed polymeric micelles

This paper reports the interaction between Pluronic F127, P123 and their mixed micelles with methylparaben and propylparaben. The UV studies revealed that, the spectral behavior of mixed micelle of F127 and P123 with parabens lay between their individual micellar behaviors. The cloud point studies have shown similar results. It was observed that the intensity of fluorescence spectra, compared with the single micelle-drug combinations was much higher with the mixed micelle-methylparaben combinations and lower with the mixed micelle-propylparaben combinations. The number of binding sites was calculated. Static nature of quenching was observed. The dissociation constant KD for methylparaben - mixed pluronic and propylparaben - mixed pluronic combinations were 21.18 × 10-3 L mol-1 and 32.57 × 10-3 L mol-1 respectively. This suggests that there was stronger binding between methylparaben and mixed micelle compared to propylparaben and mixed micelle. Dynamic light scattering studies indicated that the addition of NaCl to the mixed micelle and parabens facilitated the micellar aggregation and better encapsulation efficiency for the drug. Scanning electron microscope images showed the incorporation of methylparaben and propylparaben molecules into the surface cavities of mixed micelle, pointing towards the change in morphology. This is probably the first report on interaction study of parabens with mixed micelles.

Effect of Maltodextrin and Temperature on Micellar Behavior of Bile Salts in Aqueous Medium: Conductometric and Spectrofluorimetric Studies

Abstract Conductivity and fluorescence probe techniques have been employed to study the micellar behavior of bile salts i.e. sodium cholate (1–20 mmol⋅kg−1) and sodium deoxycholate (0.5–10.0 mmol⋅kg−1) in aqueous solutions of maltodextrin (0.0, 0.5, 1.1, and 1.6 mmol⋅kg−1) at different temperatures. The influence of maltodextrin on the micellization behavior of bile salts has been determined in terms of critical micelle concentration (CMC) values obtained from conductivity measurement. The variation in CMC values has been discussed by considering the alteration in the hydrophobic environment of maltodextrin-sodium cholate/sodium deoxycholate complex imparted by the carbohydrate molecules. In order to substantiate the CMC values determined from conductivity method, the fluorescence probe study of aqueous sodium cholate and sodium deoxycholate solutions in presence of fluorescent, pyrene has also been carried. The CMC values obtained from both techniques are in full agreement with each other. Moreover, application of charged pseudo-phase separation model has been made to discuss the thermodynamics of the system.

Soluting effect of amino acids on 1‑decyl‑3‑methylimidazolium bromide and 1‑dodecyl‑3‑methylimidazolium bromide as cationic surfactants and sodium dodecyl sulfate as anionic surfactant in aqueous solutions

In this work, with the aim of shedding light on the effect of zwitterion cosolutes (amino acids) on the aggregation and surface behaviors of both cationic and anionic surfactants in aqueous solution, surface and micellar behavior of 1‑decyl‑3‑methyl imidazolium bromide ([C10mim]Br), 1‑dodecyl‑3‑methyl imidazolium bromide ([C12mim]Br) and sodium dodecyl sulfate (SDS) in aqueous solutions of 0.7 mol·kg−1 glycine, alanine and proline were studied by means of volumetric, compression, electric conductivity and surface tension measurements at different temperatures. From the experimental density and speed of sound data, the various parameters such as apparent molar volume, isentropic compression, apparent molar isentropic compression and the change of apparent molar volume upon micellization as well as upon transfer from pure water to aqueous amino acid solutions were derived. Our results showed that the order of isentropic compression for the investigated surfactants in presence of the amino acids was: SDS > [C12mim]Br ≫ [C10mim]Br. Also the obtained negative values for transfer apparent molar volume from pure water to aqueous amino acid solutions in ternary systems of ([C10mim]Br + water + proline) and ([C12mim]Br/SDS + water + glycine/alanine/proline) indicated that hydrophobic-hydrophobic interactions are predominant. The values of the degree of ionization of the counter ion on the micelles and thermodynamic properties of micellization for the investigated surfactants in aqueous amino acids solutions were obtained from the electrical conductivity measurements. It was found that, hydrophobic-hydrophobic interactions between the aliphatic chain of surfactants and amino acids have unfavorable effects on micelle formation. From the surface tension measurements, a series of parameters, including adsorption efficiency, surface tension at CMC, surface tension at micellar phase (γmic), effectiveness for surface tension reduction, maximum surface excess concentration and minimum surface area per molecule were determined for the investigated surfactants in the presence of different amino acids at 298.15 K.All the investigated amino acids have soluting-out effect and their abilities to reduce the CMC of the surfactants in aqueous solutions decrease with an increase in the hydrophobicity of the amino acid. Resultant data showed that the ability of the amino acids to decrease the CMC followed the order: glycine > alanine ≫ proline.

Surface Tension Studies of Ternary System: Cu (II) Surfactants-2-amino-6-methyl Benzothiazole Complex Plus Methanol Plus Benzene at 311 K

Background: Exact information about micellar feature of Cu (II) Soaps play a vital role in its selection in specific phenomena such as foaming, wetting, detergency, emulsification, etc. and also in their use as herbicides, fungicides, pesticides and insecticides. Copper soaps having a tendency of complex formation with the compounds containing donor atoms like N, O, Br, S, etc. It is well known that benzothiazoles are derivatives of anilines and play significant role in biological activities and having sufficient industrial and analytical applications. Objective: Coherence of biological activities of copper soaps and benzothiazole stimulated our interest to extend the studies in their cumulative form as complexes. It is anticipated that it will generate new hopes in the pharmacological activities. Critical micelle concentration, revelation of the nature and size of micelles formed and surface active properties have been investigated in the proximity of mixed solvents having wide difference in degree of polarity. Methods: Copper soap complex solutions in polar and non-polar solvent (methanol and benzene) mixtures have been chosen for the surface tension studies. Their micellar and colloidal behaviour have been analysed and these results confirm that CMC values depend upon composition of solvent mixture and are found to decrease with increase in chain length of copper surfactant (caprylate, caprate and laurate) in the referred molecule taken for study. Results: The results of surface tensions have been explained on the basis of Szyszkowski’s empirical equation and it is observed that X, Y and (-XlnY) lead to the confirmation of fact that the change in the behaviour of copper surfactant complex occurs differently at two different compositions (40% & 80%) of methanol-benzene mixture. The results reveals that the numerical value of X for all the complexes in 40% and 80% methanol-benzene mixture below CMC are higher than above CMC. The area covered by 1 g. mole of the complex decreases gradually from 40% methanol to 80% methanol. The values of parachor of the complex solution increase with increase in the mole fraction and volume percent of methanol below CMC and decrease above CMC. The plots of parachor against the mole fraction of the copper surfactant complex are characterized by an intersection of two straight-lines at the CMC of copper surfactant complex. Conclusion: Hammic and Andrew’s equations has been successfully applied to explain the behaviour of copper surfactant complex in two different compositions of methanolbenzene mixtures.

Effects of 1‐Alkyl‐(and 1‐Benzyl)‐2,3‐Dimethylimidazolium Ionic Liquids as Additives on the Micellar Behavior of Surfactant SB‐12

AbstractThe micellization and surface‐active behavior of zwitterionic surfactant N‐dodecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propanesulfonate (SB‐12) in aqueous media were investigated in the absence and presence of different alkyl‐appended and benzyl‐appended ionic liquids (IL) 1‐butyl‐2,3‐dimethylimidazolium chloride [bdmim][Cl], 1‐butyl‐2,3‐dimethylimidazolium bromide [bdmim][Br], 1‐hexyl‐2,3‐dimethylimidazolium bromide [hdmim][Br], and 1‐benzyl‐2,3‐dimethylimidazolium chloride [bzdmim][Cl]. The characteristics of self‐organization processes in SB‐12 + IL/water systems include critical micelle concentration (cmc), aggregation number (Nagg), micellar size (D), surface, and adsorption parameters. These parameters were determined by the fluorescence and surface tension measurements. In SB‐12 solutions, cmc were found to be decreasing to different extents in the presence of all the studied IL than in pure water. The addition of IL [hdmim][Br] decreases the cmc of aqueous SB‐12 to rather a low extent. The other three IL show a prominent lowering in cmc of surfactant SB‐12 to different magnitude. The maximum lowering in cmc was observed due to addition of benzyl‐appended IL [bzdmim][Cl]. The aggregation number of aqueous SB‐12 solution obtained in general is higher at high wt.% of added IL. The average micellar size was also found to increase upon addition of IL. Both IL anions and cations interacted with the charged centers present on the zwitterionic surfactant SB‐12, which caused a substantial increase in the surface activity.

Ultrasound-Assisted Low-Density Solvent-Based Dispersive Liquid–Liquid Microextraction Coupled to Spectrophotometry for the Determination of Low Levels of Histamine in Fish and Meat Products

In this study, a new low-density solvent-based dispersive liquid–liquid microextraction strategy coupled to spectrophotometry has been developed for the determination of the trace levels of histamine in fish and meat products. The method is based on the formation of a charge transfer complex between a histamine and a phenothiazine group dye, promethazine (PMZ) in the presence of greener ionic liquid (IL), 1-butyl-3-methylimidazilium octylsulfate, C4mim octylOSO3, exhibiting a surfactant-like micellar behavior at pH 7.0, and then microextraction of the complex into the floating organic drops of 1-heptanol, which is water-immiscible and lighter than water. Ultrasound or sonication was used to improve the microextraction efficiency as well as to reduce the analysis time and cost. Variables affecting the microextraction efficiency were evaluated and optimized. Under optimal conditions, a calibration plot, which is prepared from solvent-based calibration solutions, was linear in the range of 5–750 μg L−1, with a sensitivity enhancement of 95-fold. In addition, the satisfactory extraction recoveries ranging from 95.2 to 102.8% were obtained. The method has been found to have excellent detection sensitivity, with a detection limit of 1.35 μg L−1 and intra- and inter-day precisions of 3.5–5.6% (as RSDs; n, 5 and 3 × 5). A preconcentration factor of 107-fold from the preconcentration of a 75-mL sample was obtained. The method was statistically validated by analysis of two quality control samples, including accuracy and precision studies after spiking. The method may be accepted as a simple, easy-to-use, low-cost, fast, sensitive, accurate, and reliable approach, even better than conventional DLLME and similar techniques. The results indicated that this methodology was suitable for the analysis of low levels of histamine in selected food matrices.

Solubilization and interaction of cinnamic acid and its analogues with Pluronic® micelles

The interaction of cinnamic acid (CA) and its analogues viz. p-coumaric acid (PCA) and caffeic acid (CFA) with core-shell micelles of a moderately hydrophobic Pluronic® P123 has been investigated using cloud point (CP), viscosity, dynamic light scattering (DLS), small-angle neutron scattering (SANS) and steady-state fluorescence measurements. These solubilizates alter micellar behaviour of copolymer solution dependant on their hydrophobicity. P123 micelles exhibit time-dependent restructuring and responsive growth processes at different rates, depending on pH and in the presence of additives. Thus, restructuring and growth of P123 micelles can be easily tuned up to a substantial extent just by changing the concentration of the additives and the pH of the solution. Considering the medical applications of cinnamic acid and its analogues and considering use of Pluronics® in drug delivery systems, the present study can provide important insight of the possible time-dependant delivery mechanism of drugs.

Probing effect of maltodextrin on micellar properties of bile salts at varying temperatures: A physico-chemical approach

Surfactant micelles have a profound advantage to be used as an effective vehicle for the transport phenomenon and subsequently drug delivery purposes. In this context, density (ρ), speed of sound (μ), surface tension and viscosity techniques are employed in order to evaluate the type of interactions and micellar behaviour of bile salts i.e. sodium cholate (NaC) (4 to 22 10−3·mol·kg−1) and sodium deoxycholate (NaDC) (1 to 10 10−3·mol·kg−1) in aqueous solutions of maltodextrin (0.5, 1.0, and 1.5% w/v) over wide temperature range 293.15 to 313.15 K with interval of 5 K. The volumetric parameters have been calculated in order to explain bile salt-saccharide interactions through co-sphere overlap model. The surface tension data has been prudently analyzed in terms of interfacial parameters which assist to procure competing pattern of various intermolecular interactions, modification in surface activity and micellar behaviour existing in ternary (saccharide + water + surfactant) system. The surface tension values of NaC are found to be greater than NaDC in all the studied solvent systems, which clearly reflect the greater hydrophobic nature of NaDC. The viscometric parameters corroborate well with the finding of other techniques with respect to interaction. In conclusion, the results give an indication to assess and develop surfactant immobilized maltodextrin for better biological action.

Synthesis, self-assembly and micellization characteristics of choline alkanoate ionic liquids in association with a star block copolymer

Herein, alkyl chain dependent self-assembly of choline carboxylate ionic liquids (ILs) and their effect on micellar characteristics of a star block copolymer (Tetronic®T1304) are reported. The ILs showed good aqueous solubility (low Kraft point) and formed spherical micelles. Small angle neutron scattering (SANS) analyses revealed a reduction in the critical micelle concentration (CMC) and elevation in the aggregation number (Nagg) upon increasing alkyl chain length of ILs. More importantly, ILs demonstrated good biocompatibility in murine erythrocytes and A549 cells, irrespective of the chain length.Furthermore, the effect of IL addition on micellar behaviour of T1304 was examined through thermal and scattering studies. We observed alkyl chain dependent increase in the cloud point (CP), critical micellization temperature (CMT), micelle size (Rh, Rc, Rhs) and Nagg. In association with T1304, long chain ILs (n = C12–C18) formed charged mixed micelles with a lower Nagg which showed enhanced solubilization of quercetin, a hydrophobic drug. Mixed micelles, composed with such biocompatible ILs, can further be tuned to explore their drug delivery applications.

Interaction of cationic surfactant cetyltrimethylammonium bromide (CTAB) with hydrophilic ionic liquid 1‑butyl‑3‑methylimidazolium chloride [C4mim][Cl] at different temperatures – Conductometric and FT-IR spectroscopic study

This paper delineates the effect of hydrophilic ionic liquid 1‑butyl‑3‑methylimidazolium chloride on micellar behavior of cationic surfactant cetyltrimethylammonium bromide (CTAB). Significant physicochemicalproperties like conductance, critical micelle concentration are detected to change as [C4mim][Cl] is added to aqueous CTAB. The conductivity data of surfactant CTAB in aqueous solutions of ionic liquid were experimentally determined in the temperature range from 298.15 to 308.15 K with the interval of 5 K. Obtained experimental data of conductivity have been utilized to deduce the critical micelle concentration (CMC). Using temperature dependence of CMC secured from conductivity measurements numerous thermodynamic parameters of micellization namely standard enthalpy of micellization (ΔHm0), standard free energy of micellization (ΔGm0), and standard entropy of micellization (ΔSm0) have been evaluated. FT-IR Spectra recorded for individual IL and some selected concentration to analyze the structural changes prevailed in the system. Results have been discussed in terms of effect of hydrophilic ionic liquid 1‑butyl‑3‑methylimidazolium chloride [C4mim][Cl] on the micellization process of the surfactant cetyltrimethylammonium bromide (CTAB).