Micellization and Effect of Salt Behavior on Meristyl Alcohol Based Bis-Sulfosuccinate Gemini Surfactants in Aqueous Solutions

A series of bis-sulfosuccinate anionic gemini surfactants were synthesized from meristyl alcohol (BSGSMA_1,4; BSGSMA_1,6, and BSGSMA_1,8) containing 4, 6, and 8 methylene chains as different flexible spacer lengths. The chemical structures of synthesized geminis were confirmed by using spectroscopic analytical techniques, viz., elemental analysis, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy(NMR). Investigations were carried out to examine the effect of different spacer length and different salts (organic and inorganic) on surface and fluorescence properties of prepared gemini surfactants. The results of surface properties shown that surface tension at CMC (?_CMC) and critical micelle concentration (CMC) were reduced and pC₂₀ value was enhanced with increased spacer length. Fluorescence investigations were also revealed the significance of longer spacer with the concluded remarks of higher aggregation number and reduced micropolarity for BSGSMA_1,8 having elongated flexible spacer. The results of salts studies had shown the better results for organic salts as compared to inorganic salts.     

The Self-Association and Mixed Micellization of an Anionic Surfactant,Sodium Dodecyl Sulfate,and a Cationic Surfactant,Cetyltrimethylammonium Bromide: Conductometric,Dye Solubilization,and Surface Tension Studies

In the present study, we investigate the self-association and mixed micellization of an anionic surfactant, sodium dodecyl sulfate (SDS), and a cationic surfactant, cetyltrimethylammonium bromide (CTAB). The critical micelle concentration (CMC) of SDS, CTAB, and mixed (SDS + CTAB) surfactants was measured by electrical conductivity, dye solubilization, and surface tension measurements. The surface properties (viz., C₂₀ (the surfactant concentration required to reduce the surface tension by 20 mN/m), Π_CMC (the surface pressure at the CMC), Γ_max (maximum surface excess concentration at the air/water interface), and A_min (the minimum area per surfactant molecule at the air/water interface)) of SDS, CTAB, and (SDS + CTAB) micellar/mixed micellar systems were evaluated. The thermodynamic parameters of the micellar (SDS and CTAB), and mixed micellar (SDS + CTAB) systems were evaluated.

A schematic representation of micelles and mixed micelles.     

Interaction of Nonionic Surfactant Triton-X-100 with Ionic Surfactants

The interaction in two mixtures of a nonionic surfactant Triton-X-100 (TX-100) and different ionic surfactants was investigated. The two mixtures were TX-100/sodium dodecyl sulfate (SDS) and TX-100/cetyltrimethylammonium bromide (CTAB) at molar fraction of TX-100, α_TX-100 = 0.6. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γ_CMC), maximum surface excess concentration (Γ_max), and minimum area per molecule at the air/solution interface (A _min) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were also determined. Mixtures of both TX-100/SDS and TX-100/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.     

Spectroscopic analysis of naphtholazobenzimidazole in organised solution

Micelle–water partition coefficient (K_x ) of naphtholazobenzimidazole dye (NAB) in aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) has been determined spectrophotometerically. Changes in absorption patterns of dye caused by surfactants and solvents were quantified in terms of dye–surfactant ratio (n _D/n _S) and solvent water partition coefficients (P), respectively. Multiple residence sites have been suggested for dye molecules within micelles, based on shifts in azo-hydrazone tautomeric equilibrium. Micelle–water partition coefficients were used to evaluate the influence of dye on critical micelle concentration of CTAB and SDS. At same micelle concentration, M, the relative solubility of NAB was greater in cationic surfactant CTAB than in anionic surfactant SDS.     

Interfacial and Thermodynamic Properties of Anionic‐Nonionic Mixed Surfactant System: Influence of Hydrophobic Chain Length of the Nonionic Surfactant

The influence of hydrophobic chain length in nonionic surfactants on interfacial and thermodynamics properties of a binary anionic‐nonionic mixed surfactant was investigated. In this study, nonionic surfactants lauric‐monoethanolamide (C₁₂ MEA) and myrisitic‐monoethanolamide (C₁₄ MEA) were mixed with an anionic surfactant, α‐olefin sulfonate (AOS). The critical micelle concentration (cmc), maximum surface excess (Γ_max), and minimum area per molecule (A_min) were obtained from surface tension isotherms at various temperatures. The thermodynamic parameters of micellization and adsorption were also computed. Micellar aggregation number (N_agg), micropolarity, and binding constant (K_sv) of pure and mixed surfactant system was calculated by fluorescence measurements. Rubingh's method was applied to calculate interaction parameters for the mixed surfactant systems.     

Spectrophotometric study of interaction and solubilization of procaine hydrochloride in micellar systems

The interaction of Procaine hydrochloride (PC) with cationic, anionic and non-ionic surfactants; cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and triton X-100, were investigated. The effect of ionic and non-ionic micelles on solubilization of Procaine in aqueous micellar solution of SDS, CTAB and triton X-100 were studied at pH 6.8 and 29°C using absorption spectrophotometry. By using pseudo-phase model, the partition coefficient between the bulk water and micelles, K_x, was calculated. The results showed that the micelles of CTAB enhanced the solubility of Procaine higher than SDS micelles (K_x = 96 and 166 for SDS and CTAB micelles, respectively) but triton X-100 did not enhanced the solubility of drug because of weak interaction with Procaine. From the resulting binding constant for Procaine-ionic surfactants interactions (K_b = 175 and 128 for SDS and CTAB surfactants, respectively), it was concluded that both electrostatic and hydrophobic interactions affect the interaction of surfactants with cationic procaine. Electrostatic interactions have a great role in the binding and consequently distribution of Procaine in micelle/water phases. These interactions for anionic surfactant (SDS) are higher than for cationic surfactant (CTAB). Gibbs free energy of binding and distribution of procaine between the bulk water and studied surfactant micelles were calculated.      

Micellization and mixed micellization of cationic gemini (dimeric) surfactants and cationic conventional (monomeric) surfactants: Conductometric,dye solubilization,and surface tension studies

In the present study, we have investigated the self-association, mixed micellization, and thermodynamic studies of a cationic gemini (dimeric) surfactant, hexanediyl-1,6-bis(dimethylcetylammonium bromide (16-6-16)) and a cationic conventional (monomeric) surfactant, cetyltrimethylammonium bromide (CTAB). The critical micelle concentration (CMC) of pure (16-6-16 and CTAB) and mixed (16-6-16+CTAB) surfactants was measured by electrical conductivity, dye solubilization, and surface tension measurements. The surface properties (viz., C₂₀ (the surfactant concentration required to reduce the surface tension by 20 mN/m), Π_CMC (the surface pressure at the CMC), Γ_max (maximum surface excess concentration at the air/water interface), A_min (the minimum area per surfactant molecule at the air/water interface), etc.) of micellar (16-6-16 or CTAB) and mixed micellar (16-6-16+CTAB) surfactant systems were evaluated. The thermodynamic parameters of the micellar (16-6-16 and CTAB) and mixed micellar (16-6-16+CTAB) surfactant systems were also evaluated.     

Binding on strong polyelectrolytes of mixed ionic and nonionic surfactants below their critical micelle concentration observed by fluorescence

The binding of mixed surfactants of cationic cetyltrimethylammonium bromide (CTAB) and nonionic octaethylene glycol monododecyl ether (C ₁₂E ₈) on anionic polyelectrolyte poly[2-acrylamido-2-methylpropanesulfonic acid (PAMPS)] and fluorophore-labeled copolymers containing about 40 mol% of AMPS was investigated at different mole fractions, Y , of CTAB in the surfactant mixture. The excimer emission of the cationic probe 1-pyrenemethylamine hydrochloride (PyMeA·HCl), nonradiative energy transfer (NRET) between pyrene and naphthalene labels and I ₁/ I ₃ of the pyrene label were determined by varying the total surfactant concentration, c _Surf. The I _E/ I _M value of PyMeA·HCl firstly increases and then decreases to 0 with c _Surf, showing a maximum on every curve. The critical aggregation concentration of the mixed surfactants determined from the I _E/ I _M maximum decreased from 5×10 ^-5 to 1×10 ^-5 mol/l as Y increased from 0.1 to 0.50, and then leveled off as Y increased up to unity. And at least 5×10 ^-6 mol/l CTAB was required for the mixed surfactants to bind on the PAMPS cooperatively. Equimolar binding of CTAB on AMPS was formed at I _E/ I _M=0 when Y =0.25, while at Y =0.1 some CTAB molecules in the mixed micelle were directed to the water phase without binding with AMPS. Both the intramolecular and the intermolecular NRET increased and then decreased with c _Surf, having a maximum on each curve corresponding to the equimolar binding of CTAB and AMPS so long as Y >0, indicating the coiling of the chain and interchain aggregation upon bound surfactants. The I _Py/ I _Np value at the maximum decreased with decreasing Y because more nonionic surfactant C ₁₂E ₈ participated into the polyelectrolyte-mixed surfactant complexes together with bound CTAB.     

Properties and Extraction for [Ni(NH3)6]2+ of ATPS-a Formed by Aqueous Cationic–Anionic Surfactant Mixtures

The properties and extraction for [Ni(NH₃)₆]²⁺ of anionic aqueous two-phase systems (ATPS-a) that formed in mixtures of cetyltrimethylammonium bromide (CTAB) and excess sodium dodecyl sulfate (SDS) aqueous solutions were investigated. The results showed that the properties and extraction effects were strongly affected by the surfactant concentration, the temperature of system, and the mole fraction of surfactants. The increase of temperature induces narrower phase region and larger phase volume ratio. In addition, [Ni(NH₃)₆]²⁺ was extracted into the surfactant-rich phase with higher distribution coefficient when the liquid crystal had the birefringent properties. Moreover, the distribution coefficient can be improved through reducing the concentration of surfactant from 0.15 to 0.05 mol · L^?1 or increasing mole fraction of CTAB from 21.9% to 23.1%. The results showed that ATPS of cationic–anionic surfactants was efficient for [Ni(NH₃)₆]²⁺ extraction with distribution coefficients of 13.5 when the total surfactant concentration was 0.05 mol · L^?1, mole fraction of CTAB was 21%, and temperature was 34°C.     

Influence of surfactants on the adsorption and elektrokinetic properties of the system: guar gum/manganese dioxide

The adsorption of non-ionic polysaccharide—guar gum (GG) in the presence or absence of the surfactants: anionic SDS, cationic CTAB, nonionic TX-100 and their equimolar mixtures SDS/TX-100, CTAB/TX-100 from the electrolyte solutions (NaCl, CaCl₂) on the manganese dioxide surface (MnO₂) was studied. The increase of GG adsorption amount in the presence of surfactants was observed in every measured system. This increase results from formation of complexes between the GG and the surfactant molecules. This observation was confirmed by the determination of the influence of GG on surfactants adsorption on the MnO₂ surface. The increase of GG adsorption on MnO₂ was the largest in the presence of the surfactant mixtures (CTAB/TX-100; SDS/TX-100) which is the evidence of the synergetic effect. The smallest amounts of adsorption were obtained in the presence of TX-100, which results from non-ionic character of this surface active agent. In the case of single surfactant solution CTAB has the best efficiency in increasing the amount of GG adsorption on MnO₂ which results from strong interactions with GG and also with the negatively charged surface of the adsorbent. In order to determine the electrokinetic properties of the system, the surface charge density of MnO₂ and the zeta potential measurements were performed in the presence of the GG macromolecules and the above mentioned surfactants and their mixtures. The obtained data showed that the adsorption of GG or GG/surfactants complexes on the manganese dioxide surface strongly influences the diffused part of the electrical double layer (EDL)—MnO₂/electrolyte solution, but has no influence on the compact part of the electric double layer. This is the evidence that the polymers chains are directly bonded with the surface of the solid and the surfactants molecules are present in the upper part of the EDL.     

Spectrophotometric Determination of Acidity Constants of 4‐(2‐Pyridylazo) Resorcinol in Various Micellar Media Solutions

Dissociation equilibria of 4‐(2‐pyridylazo) resorcinol (PAR) in aqueous micellar solutions were determined spectrophotometrically at 25 °C and at the constant ionic strength I = 0.1 M KNO₃. For this purpose, the effect of nonionic (Brij‐35, Triton X‐100, Triton X‐114, Triton X‐405), and anionic (SDS) surfactants on the absorption spectra of PAR at different pH values was studied. Results show that the pK_a values and pure spectra of each species of PAR are influenced by percentages of a neutral and an anionic surfactant such as Brij‐35, Triton X‐100, Triton X‐114, Triton X‐405 and SDS, respectively, added to the solution of this reagent.     

UV-Visible Spectrometric Study and Micellar Enhanced Ultrafiltration of Alizarin Red S Dye

Ultraviolet spectrometric study of alizarin red S (ARS) showed the substantial change in dye spectra by cationic CTAB as compared to anionic SDS and nonionic TX-100 surfactant. High spectral change by CTAB confirms the anionic nature of ARS dye and thus ARS-CTAB complex formation takes place due to electrostatic force of attraction. A little spectral change by SDS is the result of similarly charged repulsive forces that overcome weak hydrophobic-hydrophobic interaction between dye and surfactant micelles. TX-100 exhibited moderate spectral effect responsive to weak hydrophobic-hydrophobic interaction alone. MEUF study of ARS dye justified the spectral changes and dye rejection percentage (R) decreases in the following order: cationic > nonionic > anionic surfactant. Permeate flux (J) slightly decreases in presence of CTAB and it remains virtually constant for both SDS and TX-100. Addition of copper salt (i.e., CuCl₂) in dye-CTAB complex solution, favors rejection (%) removing dye and copper simultaneously via micellar enhanced ultrafiltration.     

Interaction of Novel Anionic Gemini Surfactants with Dodecyl Sodium Sulfate in Aqueous NaCl Medium and the Performance of Their Mixtures

The interaction in two mixtures of two novel anionic gemini surfactants, sodium 2,2′-(6,6′-(ethane-1,2-diylbis(azanediyl)bis(4-(hexylamino)-1,3,5-triazine-6,2-diyl)bis(azanediyl)diethanesulfonate (C₆-2-C₆) and sodium 2,2′-(6,6′-(ethane-1,2-diylbis(azanediyl)bis(4-(octylamino)-1,3,5-triazine-6,2-diyl) bis(azanediyl) diethanesulfonate (C₈-2-C₈), and conventional anionic surfactants, sodium dodecyl sulfate (SDS), have been investigated in 0.1 M NaCl aqueous solutions. The mixed systems are C₆-2-C₆/SDS and C₈-2-C₈/SDS, and the mole factions (α_G) of geminis are 0.1, 0.3, 0.5, 0.7, and 0.9, respectively. Mixtures of both C₆-2-C₆/SDS and C₈-2-C₈/SDS exhibit synergism in surface tension reduction efficiency and mixed micelle formation. But, all mixtures except C₆-2-C₆/SDS (α_G = 0.7), C₆-2-C₆/SDS (α_G = 0.9), and C₈-2-C₈/SDS (α_G = 0.1) don't exhibit synergism in surface tension reduction effectiveness. The performances, such as wetting, emulsification, and dispersion were measured and the results showed all mixtures posses application properties.     

Mixed micellization of an anionic gemini surfactant (GA) with conventional polyethoxylated nonionic surfactants in brine solution at pH 5 and 298 K

The micellization behavior of an anionic gemini surfactant, GA with nonionic surfactants C₁₂E₈ and C₁₂E₅ in presence of 0.1 M NaCl at 298 K temperature, has been studied tensiometrically in pure and mixed states, and the related physicochemical parameters (cmc, γ _cmc, pC ₂₀, Γ _max, and A _min) have been evaluated. Tensiometric profile (γ vs log [surfactant]), for conventional surfactants, generally consists of a single point of intersection; a gradually decreasing line (normally linear, or with slight curvature) ultimately saturates in γ at a particular [surfactant], corresponding to complete monolayer saturation. The gemini, in this report, led to two unequivocal breaks in the tensiometric isotherm. An attempt to the interpretation of the two breaks from molecular point of view is provided, depending solely on the chemical structure of the surfactant. The gemini, even in mixed state with the conventional nonionic surfactants C₁₂E₅ and C₁₂E₈, manifested the dual breaks; of course, the dominance of the feature decreases with increasing mole fraction of the nonionics in the mixture. Theories of Clint, Rosen, Rubingh, Motomura, Georgiev, Maeda, and Nagarajan have been used to determine the interaction between surfactants at the interface and micellar state of aggregation, the composition of the aggregates, the theoretical cmc in pure and mixed states, and the structural parameters according to Tanford and Israelachvili. Several thermodynamic parameters have also been predicted from those theories.     

Effect of (chloride salt) electrolytes on the mixed micellization of (equimolar) a cationic gemini (dimeric) surfactant and a cationic conventional (monomeric) surfactant

Herein we report the effect of (chloride salt) electrolytes on the mixed micellization of (equimolar) a cationic gemini (dimeric) surfactant, hexanediyl-1,6-bis(dimethylcetylammonium bromide) (16-6-16), and a cationic conventional (monomeric) surfactant, cetyltrimethylammonium bromide (CTAB) in aqueous solutions. In absence and presence of (chloride salt) MCl (where M?Li, Na, and K) electrolytes, the critical micelle concentration (CMC) of mixed (16-6-16 + CTAB) surfactants was measured by surface tension measurements. With increasing the concentration of electrolyte, the CMCs were increasing. The surface properties and the thermodynamic parameters of the mixed micellar systems were also evaluated. From these evaluated thermodynamic parameters, it was found that in presence of electrolyte the stability of the mixed micellar system is more.     

Rheological Study of Interactions between Anionic Guar and Oppositely Charged Surfactant

We have studied the interactions between anionic carboxymethyl guar (CMG) and oppositely charged surfactant: dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), and gemini surfactants (16-4-16), using rheological measurements. In the present study, two competing forces, electrostatic interaction and hydrophobic interaction, have been identified as important factors. Various types of structure formed on the anionic CMG chains are qualitatively discussed in comparison. For example, C₁₂TAB and gemini surfactant tend to form polymer-bound aggregates, whereas the C₁₆TAB tend to form the polymer-associated architecture. Furthermore, possible mechanisms based on the experimental results to elucidate these interesting phenomena have been proposed and discussed.     

Mixing Behavior of Conventional and Gemini Cationic Surfactants

Micellization behavior of cationic monomeric surfactants, hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB), cetylpyridinium chloride (CPC), tetradecyltrimethylammonium bromide (TTAB), and dimeric (gemini) cationic surfactant pentamethylene‐1, 5‐bis(hexadecyldimethylammonium bromide) with formula C₁₆H₃₃(CH₃)₂N⁺(CH₂)₅N⁺(CH₃)₂C₁₆H₃₃ · 2Br^?, abbreviated as 16‐5‐16, in mixed states (binary) have been studied by conductivity. The micellar compositions, activities of the components, and their mutual interactions have been estimated from Rubingh's theory. The mixtures show nonideal behavior with favorable interactions.     

Aqueous Two‐Phase System (ATPS) Containing Gemini (12‐3‐12,2Br−) and SDS I: Phase Diagram and Properties of ATPS

Two phases coexist in an aqueous system that contains the two surfactants cationic gemini 12‐3‐12,2Br? and anionic SDS. An aqueous two‐phase system (ATPS) is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic‐anionic surfactant systems. In that region, the molar ratio of gemini to SDS varies with the total concentration of surfactants. ATPS not only has higher stability but also has longer phase separation time for the new systems than that of the traditional system. Furthermore, the optical properties of ATPS are different at different total concentrations. All of these experimental observations can be attributed to the unique properties of gemini surfactant and the synergy between the cationic gemini surfactant and the anionic surfactant SDS.     

Quenching of zinc phthalocyanine excited states by viologen surfactant assemblies——The influence of microenvironment

A series of functional surfactants of N-alkyl-N'-butyl viologens has been synthesized.The quenching of excited singlet and triplet states of zinc phthalocyanine was studied in DMSOand in mixed micelles containing the functional surfactant as one and cationic cetyl trimethylam-monium bromide(CTAB),anionic sodium dodecylsulfate(SDS)and neutral TX-100 surfactantas the other component.Fluorescence quenching and laser photolysis studies indicate that thefunctional surfactants are solubilized at different sites in micelles,the process depends on chainlength and exerts great influence on the quenching of zinc phthalocyanine excited states.     

Interaction of the Amphiphilic Drug Amitriptyline Hydrochloride with Gemini and Conventional Surfactants: A Physicochemical Approach

Pyrene fluorescence measurements were carried out on various binary mixtures of the antidepressant amphiphilic drug amitriptyline hydrochloride (AMT) with conventional (TTAB and CTAB) and gemini surfactants (14-4-14 and 16-4-16). In all cases mixed micellar aggregates were formed and the mixed critical micelle concentration (cmc) of various mixtures was computed from the I ₁/I ₃ versus total surfactant concentration plots. In the region where mixed micelles are formed, the interaction of the amphiphlic drug and four surfactants showed synergistic behavior. The results were analyzed using an interaction parameter, β, which characterize the interaction in the mixed micelle and is introduced by a regular solution theory. The β values are negative in all binary mixtures, and their magnitudes increase with increasing hydrophobicity of the amphiphile. The micellar mole fraction of AMT in the mixed micelle (x ₁) and in the ideal sate (x _ideal) were evaluated and their values (x ₁ > x _ideal) suggest that the contribution of the AMT component is greater in binary mixtures as compared to that in the ideal state. Activity coefficients (f ₁ and f ₂) and excess Gibbs energy (G _ex) were also calculated. The values of micelle aggregation numbers (N _agg) and various other parameters like the Stern–Volmer constant (K _sv), micropolarity and dielectric constant of mixed systems have also been evaluated from the ratios of respective peak intensities (I ₁/I ₃ or I ₀/I ₁).