Micelle Concentration Of Cationic Surfactants Research Articles

Determining the critical micelle concentrations of cationic surfactants based on the visible-light-induced oxidase-like activity of fluorescein

As the critical micelle concentration (CMC) is one of the essential parameters of surfactant, the determination of CMC value is of great significance. We explored a facile and novel strategy based on the visible-light-induced oxidase-like activity of fluorescein for determining the CMC value of cationic surfactants. Fluorescein as a visible-light-induced oxidase mimic can catalyze the change of 3,3′,5,5′-tetramethylbenzidine (TMB) from colorless to blue (oxidation state TMB) under visible light illumination. Nevertheless, it was worth noticed that cationic surfactant could significantly inhibit the catalytic activity of fluorescein with a concentration-dependent mode due to the electrostatic interaction between negatively charged fluorescein and cationic surfactant in aqueous solution. With the increased of surfactants concentrations, the absorbance of the oxidation state TMB was decreased. As the concentration of cationic surfactant reached CMC, the catalytic activity of fluorescence was almost inhibited completely. Therefore, this novel and convenient spectrometric method provides a new idea for the determination of CMC value and also broadens the application of small molecule mimic enzymes.

On the Head Group Effect on Critical Micelle Concentration of Cationic Surfactants Using Molecular Connectivity Indices and Atomic Partial Charges

The influence of the head group structure on the critical micelle concentration of cationic surfactants, mainly quaternary ammonium bromide salts with one alkyl tail, has been studied theoretically by QSPR using molecular connectivity indices and also the atomic partial charges. Two models obtained allow to study the effect of head group structure modification on the value of the critical micelle concentration. The model, which contains molecular connectivity indices together with the charge localized on the central nitrogen atom, has a wider descriptive capability than the model which contains topological indices only. The present semi-empirical charge investigations of different quaternary ammonium salts show that the charges of the quaternary ammonium head groups are approximately the same, but one of the obtained models shows that the significant part of that charge, which is localized on the central nitrogen atom, affects the value of the critical micelle concentration.

Interaction of Dyes with Cationic Surfactants in Solutions: Determination of Critical Micelle Concentration

Interactions of sulforhodamine B or ethyl eosin (as the anionic dye) with cetylpyridinium bromide (as a cationic surfactant) have been investigated by visible spectroscopy in aqueous solution. The object of research is the association between an anion of dye and of cationic surfactant in aqueous solutions and its features. Computer simulation of these interactions was carried out with the use of AM1 and PM3 semi-empirical methods. A new spectrophotometric method was developed for determination of critical micelle concentration of cationic surfactants.

Interaction of Dyes with Cationic Surfactants in Solutions: Determination of Critical Micelle Concentration

Interactions of sulforhodamine B or ethyl eosin (as the anionic dye) with cetylpyridinium bromide (as a cationic surfactant) have been investigated by visible spectroscopy in aqueous solution. The object of research is the association between an anion of dye and of cationic surfactant in aqueous solutions and its features. Computer simulation of these interactions was carried out with the use of AM1 and PM3 semi-empirical methods. A new spectrophotometric method was developed for determination of critical micelle concentration of cationic surfactants.

Catanionic and chain-packing effects on surfactant self-assembly in the ionic liquid ethylammonium nitrate

HypothesisMicelle formation, particularly the formation of compact, globular micelles in the high ionic strength environment of an ionic liquid, seems to be at odds with the principle of opposing forces and the concept of the surfactant packing parameter. Here we examine how interactions between polar head-groups, with solvent ions, and chain packing affect self-assembly structure in ionic liquids. ExperimentsThe self-assembly of pure cationic and anionic surfactants, their catanionic mixtures, and the effect of the cosurfactant tetradecanol in the ionic liquid ethylammonium nitrate (EAN) is investigated by small-angle neutron scattering (SANS). FindingsThe critical micelle concentrations of cationic surfactants are much higher and micelles much smaller in EAN than in water, whereas anionic micelles are less dramatically affected. Catanionic surfactant mixtures form small micelles in EAN at all compositions, unlike their counterparts in water which form vesicle dispersions or precipitates near 1:1 mol ratios. This contrasts with the behavior of cationic surfactants when mixed with double-chained analogs or alkanol cosurfactants, which induce micelle growth and shape transitions to rod-like and bilayer aggregates through chain packing effects similar to aqueous systems. This enables the aggregate morphology in the ionic liquid to be controlled through the composition of the surfactant mixtures.

Utilization of surface Plasmon resonance band of silver nanoparticles for determination of critical micelle concentration of cationic surfactants

We have utilized surface Plasmon resonance (SPR) band sensitivity to surfactant concentration to investigate the critical micelle concentration (cmc) of CTAB, HY and CPB. The process is based upon an in situ formation of silver nanoparticles (AgNPs) through the reduction of silver ions (Ag+) by diethylene triamine (DETA) at 25°C. In the presence of cationic surfactants, Ag+ ions can be reduced to AgNPs in a few minutes, accompanied by changes in intensity and wavelength of the SPR band. The spectral shifts of SPR band and the change of color have been used to determine CMC values of cationic surfactants.

Determination of critical micelle concentration of cationic surfactants by surface-enhanced Raman scattering

A novel approach, based on surface-enhanced Raman scattering (SERS) and 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) functionalized silver nanoparticles, was developed to determine the critical micelle concentration (CMC) of cationic surfactants. A graph was generated by plotting the Raman intensity ratio between the aromatic ring vibration of DTNB at 1558 cm−1 and its symmetric nitro stretching at 1333 cm−1 as a function of surfactant concentration. An abrupt change of slope at a particular concentration was shown to reliably predict the CMC of cetyltrimethylammonium bromide (CTAB).

QSPR with extended topochemical atom (ETA) indices, 3: Modeling of critical micelle concentration of cationic surfactants

The ability of surfactant molecules to facilitate solubilization of essential chemical entities accounts for their wide application in the pharmaceutical industry. The solubilization ability begins at concentrations exceeding the critical micelle concentration (CMC) which in turn is influenced by the molecular structure of the surfactants. Here, attempts have been made to explore the essential molecular fragments determining CMC of cationic surfactants using in silico technique. Different classes of descriptors (ETA and non-ETA) were correlated with the CMC data of a series of cationic surfactants to develop predictive models. Models were developed using genetic function approximation technique and were extensively validated employing different validation statistics. Comparative analysis was performed between the best model developed using the ETA descriptors and that obtained with the non-ETA variables. The results revealed that the external predictive potential of the ETA model was superior to the non-ETA model. The results also indicated that the ETA model could efficiently determine the CMC profile of the untested molecules. Finally, the two classes of descriptors were combined and the QSPR model thus obtained exhibited improved external predictive potential. The ETA descriptors implicated the importance of molecular size and their degree of unsaturation while the non-ETA descriptors signified impact of the bond order and the number of fragments bearing hydrogen atoms attached to carbon atoms with variable hybridization. Thus, addition of ETA descriptors improved the model quality extensively identifying essential molecular fragments contributing to their CMC profile and can be comprehensively utilized for property prediction of new cationic surfactants.

The effect of sugars on the temperature dependence of the critical micelle concentrations of cationic surfactants.

Abstract The temperature dependence of the critical micelle concentrations (cmc) of decyl, dodecyl and tetradecyl trimethylammonium and dodecyl benzyl dimethylammonium bromides in the presence of glucose or sucrose is reported. Thermodynamic parameters have been calculated using the uncharged phase-change model. An interpretation of the changes in cmc values, relative to those in simple aqueous solutions, is offered in terms of the resultant of two effects, namely modifications in water-structure and reduction of dielectric constant.

Prediction of critical micelle concentration of cationic surfactants using connectivity indices

Relationship for predicting Logcmc for cationic surfactants having chloride as counterion from only molecular connectivity indices was found. It is suggested that the index 0χν includes some information about hydrophobicity while indices 4χ pc and $${^{4}\chi^{\nu}_{pc}}$$ include some information about hydrophilicity of the cationic surfactants studied. The structures of 23 compounds used for the correlation are quite diverse.

QSPR study of the first and second critical micelle concentrations of cationic surfactants

Linear and nonlinear predictive models are derived for 50 ammonium and quaternary pyridinium cationic surfactants. Multilinear models were developed for both the first and second critical micelle concentrations (CMCs). Additionally, a general ANN model was deduced for the first CMC of all 50 cationic surfactants. Most of the descriptors in these models are related to the size and charge of the hydrophobic tail and to the size of the head. The multilinear model for the second CMC was more closely related to the hydrophobic domain of the surfactant than that of the first CMC. The QSPR models (linear and nonlinear) for the first CMC in this work could provide useful predictions of the CMC of structurally similar cationic surfactants.

Determination of the Critical Micelle Concentration of Cationic Surfactants by Capillary Electrophoresis

The determination of the critical micelle concentration (CMC) of cationic surfactants by capillary electrophoresis was demonstrated. In this study, tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DoTAB) were selected as cationic surfactants and propazine was chosen as test solute. In the evolution of the effective electrophoretic mobility of propazine as a function of surfactant concentration, a dramatic change in slope at a particular concentration is a good indication of the CMC of this surfactant. The CMC values determined experimentally were further confirmed by a curve-fitting approach. Simulation of the electrophoretic mobility curves as a function of surfactant concentration in both micellar electrokinetic chromatography and capillary zone electrophoresis using cationic surfactants as an electrolyte modifier was performed for propazine, and the intersection of these two mobility curves allowed us to precisely predict the CMC of the surfactant. The CMC values determined for TTAB and DoTAB are 1.6 ± 0.1 and 11.0 ± 0.1 mM, respectively, in the case of an electrolytic solution consisting of 70 mM phosphate buffer at pH 6.0. Moreover, the applicability of the electroosmotic mobility as a parameter for the determination of the CMC was examined.

Determination of the Critical Micelle Concentration of Cationic Surfactants: An Undergraduate Experiment

A novel method based on the catalytic effect of micelles exerted by cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB), respectively, on the indicator reaction between H2O2 and...

Measurement of Critical Micelle Concentrations of Cationic Surfactants by Capillary Electrophoresis

Measurement of Critical Micelle Concentrations of Cationic Surfactants by Capillary Electrophoresis

Migration behavior and selectivity of β-blockers in micellar electrokinetic chromatography: Influence of micelle concentration of cationic surfactants

The influence of micelle concentration of cationic surfactants on the migration behavior and selectivity of ten β-adrenergic blocking agents in micellar electrokinetic chromatography (MEKC) were systematically investigated at pH 6.5 and 7.0. Tetradecyl- and hexadecyltrimethylammonium bromides (TTAB and CTAB) were selected as cationic surfactants. The results indicate that, in addition to buffer pH, micelle concentration is an important separation parameter that influences the migration and selectivity of β-blockers in MEKC. The migration behavior and selectivity of labetalol and propranolol are most markedly affected. The resolution of peaks between atenolol, metoprolol and levobunolol greatly enhances on increasing the micelle concentration. In contrast, the peaks between acebutolol and nadolol and those between timolol and atenolol become unresolvable at concentrations near 30 mM at pH 7.0. Complete separation of these β-blockers was achieved either with CTAB and TTAB at a concentration in the range 15–20 mM and 12–15 mM, respectively, at pH 7.0 or with CTAB at a concentration in the range 27–30 mM at pH 6.5. Moreover, partition coefficients of β-blockers between the aqueous and micellar phases at pH 7.0 were evaluated. The plot of the logarithm of migration factor (log k′) versus the logarithm of octanol–water partition coefficient (log Pow) reveals that, the migration of β-blockers possessing small hydrogen bond strength depends on the extent of micellar solubilization based on hydrophobic interactions, whereas the migration and selectivity of β-blockers with hydrogen bond donor characteristics are influenced considerably by hydrogen bonding interactions, in addition to hydrophobic interactions, in MEKC.

Reinvestigation of the critical micelle concentrations of cationic surfactants with the use of an ammonium 8-anilino-1-naphthalenesulphonate fluorescent probe

Although previous studies have shown that the critical micelle concentration of the hexadecyltrimethylammonium bromide cationic surfactant could not be determined by using an ammonium 8-anilino-1-naphthalenesulphonate (ANS) fluorescent probe, we found that this probe can monitor micelle formation to a significant extent when used in a solution of high ionic strength. The present results suggest that ANS can be used to estimate the critical micelle concentrations of various cationic surfactants under physiological conditions.

Measurement of the activity and critical micelle concentration of cationic surfactants using an inorganic ion exchange membrane electrode

Measurement of the activity and critical micelle concentration of cationic surfactants using an inorganic ion exchange membrane electrode

Measurement of the activity and critical micelle concentration of cationic surfactants using an inorganic ion exchange membrane electrode

Measurement of the activity and critical micelle concentration of cationic surfactants using an inorganic ion exchange membrane electrode

Measurement of activity and critical micelle concentration of cationic surfactants using a clay membrane electrode

A clay membrane electrode has been used to determine the activity of some surfactant cations. The critical micelle concentrations of cetylpyridinium bromide, dodecylpyridinium bromide and cetyltrimethylammonium bromide have been calculated by observing the change in e.m.f. with change in the concentration of surfactant solution. The values obtained are in reasonable agreement with those reported in the literature.

Measurement of activity and critical micelle concentration of cationic surfactants using a clay membrane electrode

Summary A clay membrane electrode has been used to determine the activity of some surfactant cations. The critical micelle concentrations of cetylpyridinium bromide, dodecylpyridinium bromide and cetyltrimethylammonium bromide have been calculated by observing the change in e.m.f. with change in the concentration of surfactant solution. The values obtained are in reasonable agreement with those reported in the literature.