Cationic Gemini Surfactants Research Articles

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

ABSTRACTIn 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), ΠCMC (the surface pressure at the CMC), Γmax (maximum surface excess concentration at the air/water interface), Amin (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.

A spectroscopic and molecular dynamic approach on the interaction between ionic liquid type gemini surfactant and human serum albumin

The interactions of imidazolium bashed ionic liquid-type cationic gemini surfactant ([C12-4-C12im]Br2) with HSA were studied by fluorescence, time-resolved fluorescence, UV-visible, circular dichroism, molecular docking and molecular dynamic simulation methods. The results showed that the [C12-4-C12im]Br2 quenched the fluorescence of HSA through dynamic quenching mechanism as confirmed by time-resolved spectroscopy. The Stern–Volmer quenching constant (Ksv) and relevant thermodynamic parameters such as enthalpy change (ΔH), Gibbs free energy change (ΔG) and entropy change (ΔS) for interaction system were calculated at different temperatures. The results revealed that hydrophobic forces played a major role in the interactions process. The results of synchronous fluorescence, UV-visible and CD spectra demonstrated that the binding of [C12-4-C12im]Br2 with HSA induces conformational changes in HSA. Inquisitively, the molecular dynamics study contribute towards understanding the effect of binding of [C12-4-C12im]Br2 on HSA to interpret the conformational change in HSA upon binding in aqueous solution. Moreover, the molecular modelling results show the possible binding sites in the interaction system.

Application of Conductance Study to Analyze Micellization Behavior of Cationic Gemini Surfactants in Water and Water–Ethanol Solvent Mixed Media

The paper presents the analysis of micellization behavior of cationic gemini surfactants with similar structures with varying atom number in spacer: heptylene-1,7-bis(dimethyloctylammonium) bromide (8–7–8) and octylene-1,8-bis(dimethyloctylammonium) bromide (8–8–8) in water and water–ethanol solvent mixed media. Experiments were carried out by using conductometric method within the temperature range of 288.15–323.15 K. The values of micellization parameters and thermodynamic functions of aggregation [critical micelle concentration (cmc), the degree of dissociation of micelles (α), enthalpy of micellization (ΔHmo), entropy of micellization (ΔSmo), Gibbs free energy of micellization (ΔGmo] within the temperature range investigated were determined. Based on the investigations performed it has been shown that the systems containing the additives ethanol have a positive value ΔGtranso, a more positive value ΔGmo, and a higher value of α and cmc as compared to pure water what confirms that the micellization pro...

Novel Triazine Schiff Base-Based Cationic Gemini Surfactants: Synthesis and Their Evaluation as Antiwear, Antifriction, and Anticorrosive Additives in Polyol

Two novel triazine Schiff base-based cationic gemini surfactants namely N,N′-bis{(p-(N,N,N-tetradecyldimethylammonium bromide)benzylidene} 6-methyl-1,3,5-triazine-2,4-diamine (14-MTR-14) and N,N′-bis{(p-(N,N,N-tetradecyldimethylammonium bromide)benzylidene} 6-phenyl-1,3,5-triazine-2,4-diamine (14-PTR-14) were synthesized following the two-step reaction. First the intermediate adduct was synthesized by reaction of the 4-(dimethylamino)benzaldehyde with 1-bromotetradecane. In the second step, the germinal surfactants 14-MTR-14 and 14-PTR-14 were synthesized by imine coupling with this intermediate adduct with 6-methyl-1,3,5-triazine-2,4-diamine and 6-phenyl-1,3,5-triazine-2,4-diamine, respectively. Both were characterized using elemental analysis (CHN), infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetry (TG). The compounds were then evaluated as anticorrosive and lubricity improver additive in polyol lube base oil. Both the surfactants show the similar anticorros...

Gemini Surfactants with Polymethylene Spacer: Supramolecular Structures at Solid Surface and Aggregation in Aqueous Solution

AbstractAggregation of α,ω‐bisammonium cationic gemini surfactants with a variable polymethylene spacer and two dodecyl chains has been studied on a solid surface and in aqueous solution. Scanning electron microscopy and dynamic light scattering with the time‐resolved fluorescence quenching technique were used for the experiments on the solid surface and in aqueous solution, respectively. As the results from the scanning electron microscopy indicate, the morphology of supramolecular structures of gemini surfactants at the solid surface depends on the spacer length. In aqueous solution, gemini surfactants with spacers consisting of 4, 6, 8, 10, and 12 CH2 groups form spherical micelles with diameters between 2 and 3.5 nm. Micelles of gemini surfactant with a short ethylene spacer show an increase in size up to 13 nm at the maximum concentration investigated. The aggregation number of micelles determined by time resolved fluorescence quenching was found to be in the range 14–25 for the spacer lengths from 6 to 12 CH2 groups with only a moderate increase with surfactant concentration. For micelles of gemini surfactants with the short ethylene spacer, the increase of the aggregation number up to 50 at the maximum concentration was observed. The findings support micellar growth of gemini surfactants with short ethylene spacer.

Rheological response of methylcellulose toward alkanediyl-α,ω-bis(dimethylcetylammonium bromide) surfactants with varying spacer length

The modulation of properties of methylcellulose (MC) by cationic gemini surfactants with varying spacer lengths was studied employing tensiometry, rheometry and turbidimetry. Surface tension measurements anticipate that the gemini surfactant with longer spacer chain length saturates MC at lower concentrations owing to its greater hydrophobicity compared to shorter spacer analogues. Rheometric and turbidimetric measurements suggest that at very low concentrations of gemini surfactants, ion-dipole type of interactions between MC and gemini surfactants promote the extension of polymer chains which is manifested by an initial increase in the low shear viscosity and gelation temperature of MC–gemini surfactant systems, and lowering of turbidity. Such interactions were found to be stronger in case of 16-4-16 than 16-5-16, and almost absent in case of 16-6-16 surfactant system. However at concentrations above CAC, hydrophobic forces operative between MC and gemini surfactants were found to be more for 16-6-16 than that of 16-5-16 and 16-4-16. The final levelling of MC viscosity in presence of all the three gemini surfactants and the variation of gelation temperature suggests the solubilization of network junctions in the surfactant micelles. Moreover, the presence of gemini surfactant strongly affects the interaction of MC with a model hydrophobic drug rifampicin.The results highlight the importance of gemini surfactants and their spacer length in controlling the structural dynamics of MC and its effective use in pharmaceutical and food industry.

Role of cationic gemini surfactants (m-s-m type) on the oxidation of d-glucose by permanganate

Cationic gemini (m-s-m type; m=16, s=4,5,6) surfactants were used to determine the micelles assisted kinetics parameters, mechanism of permanganate-D-glucose redox system in an aqueous solution by means of UV–visible spectroscopy at 40°C. Effects of different [gemini surfactant], [permanganate], [D-glucose] and temperature on the reaction rate were investigated. Various activation parameters such as activation energy (Ea), enthalpy of activation (ΔH#), free energy of activation (ΔG#), and entropy of activation (ΔS#) have been evaluated. Menger-Portony pseudo-phase model modified by Bunton was used to analyze the role of gemini surfactant on the rate constant. Spacer chain length of surfactants has significant impact on the oxidation -reduction kinetics. A suitable mechanism reliable with the experimental results has been proposed and discussed. The cationic gemini surfactant micellar media are relatively more efficient than conventional monomeric surfactant i.e. cetyltrimethylammonium bromide (CTAB).

Unfolding of human serum albumin by gemini and single-chain surfactants: A comparative study

Abstract The interactions of human serum albumin (HSA) with four cationic gemini surfactants and four single-chain surfactants have been investigated from the measurements of fluorescence spectroscopy, dynamic lights scattering (DLS), zeta potential, and circular dichroism (CD). The fluorescence results show the binding strength of surfactants to HSA, along with the blue shift under the maximum emission wavelength (λmax) which is sensitive to the protein conformations. It has been found that the hydrodynamic diameters of the protein aggregates are enlarged and the electrokinetic potentials of them get positive with increasing the concentration of the surfactants. The conformational transformation of the secondary structures of surfactant–HSA aggregates has been confirmed through the quantitative analysis of the CD spectra. The isothermal titration microcalorimetry (ITC) has been employed to further analyze the binding process of single-chain surfactants to HSA. The comprehensive results obtained from various approaches have shown that both hydrophobic and electrostatic interactions are present in the cationic surfactant–HSA systems. Compared with the corresponding single-chain surfactants, the gemini ones have much stronger binding ability to induce the unfolding of HSA. These investigations on the interactions between HSA and surfactants with the altered chain architecture in different concentration regimes can facilitate the application of surfactant-protein systems in pharmaceutical, biotechnology and related fields.

Temperature-Induced Aggregate Transitions in Mixtures of Cationic Ammonium Gemini Surfactant with Anionic Glutamic Acid Surfactant in Aqueous Solution.

The aggregation behaviors of the mixtures of cationic gemini surfactant 1,4-bis(dodecyl-N,N-dimethylammonium bromide)-2,3-butanediol (C12C4(OH)2C12Br2) and anionic amino acid surfactant N-dodecanoylglutamic acid (C12Glu) in aqueous solution of pH = 10.0 have been studied. The mixture forms spherical micelles, vesicles, and wormlike micelles at 25 °C by changing mixing ratios and/or total surfactant concentration. Then these aggregates undergo a series of transitions upon increasing the temperature. Smaller spherical micelles transfer into larger vesicles, vesicles transfer into solid spherical aggregates and then into larger irregular aggregates, and entangled wormlike micelles transfer into branched wormlike micelles. Moreover, the larger irregular aggregates and branched micelles finally lead to precipitation and clouding phenomenon, respectively. All these transitions are thermally reversible, and the transition temperatures can be tuned by varying the mixing ratios and/or total concentration. These temperature-dependent aggregate transitions can be elucidated on the basis of the temperature-induced variations in the dehydration, electrostatic interaction, and hydrogen bonds of the headgroup area and in the hydrophobic interaction between the hydrocarbon chains. The results suggest that the surfactants carrying multiple binding sites will greatly improve the regulation ability and temperature sensitivity.

Effect of Spacer and Alkyl Chain Groups of the Synthesized Cationic Gemini Surfactants on the Surface Modification of Nano Na-Montmorillonite and its Dye Adsorption from Textile Waste Water

Cationic surfactants as new modifiers for clays affect the clay interlayer structure. In this paper the effect of chain length of gemini surfactants on the interlayer changes of Na-montmorilinite and its dye adsorption from waste water has been reported. Several novel quaternary ammonium cationic gemini surfactants having vaious alkyl chain and spacer lengths were synthesized according to reaction of tertiary amine with corresponded alkyl halide. Subsequently organoclays were prepared by intercalation of synthesized gemini cationic surfactants (2–6–2, 2–10–2, 4–6–4, 4–10–4 and 10-6-10 and conventional cationic surfactants (mono)) onto Na-montmorillonite (MMT-Na+) via ion exchange reaction. The structures of the synthesized surfactants were analysed using 1H NMR, 13C NMR and FT-IR spectroscopy techniques. The modified montmorillonite was also characterized by FT-IR spectroscopy of attenuated total reflection (ATR) and X-ray diffraction techniques (XRD). The results show that gemini surfactants have better intercalation than conventional ones. The basal spacing of modified montmorillonite increase with incorporation of gemini surfactants having longer spacer length and chains length. However, gemini surfactant, 4-10-4 and 10-6-10 were more effective in this regards. Dye adsorption experiments show that by surface modification, the adsorption capacity of acid dye improves and MMT-Na+ modified with gemini surfactants show higher dye adsorption capacity compared to the montmorillonite modified with conventional one (Mono) and as the alkyl chain and spacer length of the surfactants increase, this property increases. Our findings show that these kind of modifications on Na-montmorillonite can make it a promising absorbent for organic pollutants such as dye removal from waste water.

Wettability of coal pitch surface by aqueous solutions of cationic Gemini surfactants

Abstract The purpose of this experiment is to confirm the adsorption characteristics at liquid–gas and CP–liquid interfaces in relation to CP wetting with a sequence of cationic Gemini surfactant solutions and to reduce the workload of screening of surfactant. A series of cationic Gemini surfactants with different hydrophobic chain length was synthesized (C n -8-C n , n = 8, 10, 12, 14, 16). Their wettability and adsorption mechanism for coal pitch (CP) were investigated by the sessile drop analysis and electrophoresis. Within the whole range of concentration, the Zisman theory is not in accordance with the wettability on the coal tar pitch when carbon atoms of hydrophobic chains exceed 12. Meanwhile, no liner dependence was observed between adhesion tension ( γ lg cos θ ) and surface tension ( γ lg ). In addition, with the increase of surfactant concentration, Zeta potential on the surface of the CP changed from negative to positive and finally leveled off after a certain concentration. The corresponding concentration of zero potential was at least an order of magnitude lower than CMC. C 12 -8-C 12 can significantly change the wettability of the CP. According to the wetting data and Zeta potential of Gemini surfactant on CP, it can be inferred that wetting was a concerted action as a result of electrostatic interaction and van der waals adsorption. Therefore, wetting process can be generally divided into three stages.

Synthesis, Surface and Antimicrobial Activities of Cationic Gemini Surfactants with Semi‐Rigid Spacers

AbstractFour cationic gemini surfactants featuring semi‐rigid spacers were synthesized via a two‐step process. The surface‐active properties of these surfactants were investigated through surface tension and electrical conductivity measurement. The thermodynamic parameters of micellization were evaluated from electrical conductivity measurements at temperatures ranging from 293 to 313 K. The aggregation behavior of these synthesized gemini surfactants in water were investigated using dynamic light scattering and transmission electron microscopy. Further, the antimicrobial activities of these synthesized gemini surfactants against both Gram‐positive and Gram‐negative bacteria were also investigated.

Sulfidogenic-corrosion inhibitory effect of cationic monomeric and gemini surfactants: planktonic and sessile diversity

A cationic monomeric surfactant (CMS) and a cationic gemini surfactant (CGS) were successfully synthesized and characterized. Both surfactants prevent sulfidogenic activity in bulk phase and on metal surface (biofilms) at a salinity of 3.18% NaCl.

Thermodynamic and micellization studies of a cationic gemini surfactant 16-6-16: Influence of ascorbic acid and temperature

Herein, we report the study of the influence of ascorbic acid and temperature on the micellization of a cationic gemini surfactant, hexanediyl-1,6-bis(dimethylcetylammonium bromide), 16-6-16. The critical micelle concentration (CMC) of 16-6-16 was measured by the conductivity method and dye solubilisation technique. A tendency of the CMC values to increase with temperature and upon the adding of ascorbic acid was found. The standard Gibbs energy, standard enthalpy, and standard entropy of micellization of 16-6-16 were evaluated. The results of calculations suggest the decrease of the stability of the 16-6-16 micellar solution in the presence of ascorbic acid.

The cholesterol aided micelle to vesicle transition of a cationic gemini surfactant (14-4-14) in aqueous medium

Cholesterol aided micelle to vesicle transition of cationic gemini surfactant (14-4-14) in solution has been investigated.

Interaction of cationic gemini surfactant tetramethylene-1,4-bis(dimethyltetradecylammonium bromide) with anionic polyelectrolyte sodium carboxymethyl cellulose, with two different molar masses, in aqueous and aquo-organic (isopropanol) media

Interactions of the cationic gemini surfactant, 14-4-14 with anionic polymer, NaCMC.

Interactions in the mixed micelles of monomeric and gemini surfactants: Influence of some co-solvents as a function of temperature

Mixed micellar behavior of a series of m-2-m cationic gemini surfactants (where m=10, 12 and 14) with monomeric surfactants (dodecyltrimethylammonium bromide, tetradecyltrimethyl-ammonium bromide and cetyltrimethylammonium bromide) has been studied in aqueous and in aqueous n-propanol, n-butanol, tertiary butanol, propylene glycol and glycerol solutions using conductivity, surface tension, viscosity and dynamic light scattering techniques at 298.15, 308.15 and 318.15K, respectively. In mixtures of 10–2–10 with monomeric surfactants, the synergistic interactions increase with the chain length of monomeric surfactants whereas the mixtures with 12–2–12 and 14–2–14 exhibit the opposite trends. However, the synergistic interactions decrease with the increase in temperature of all the mixtures. The thermodynamic and surface parameters have been evaluated and the influence of the variations in hydrophobic chain length of the surfactants and the type of the co-solvent on these parameters has been discussed. The hydrodynamic diameter increases with the chain length of the surfactants.

Unique Phase Behaviors in the Gemini Surfactant/EAN Binary System: The Role of the Hydroxyl Group.

The hydroxyl group in the spacer of a cationic Gemini surfactant (12-3OH-12) caused dramatic changes of the phase behaviors in a protic ionic liquid (EAN). Here, the effects of the hydroxyl group on micellization and lyotropic liquid crystal formation were investigated through the surface tension, small-angle X-ray scattering, polarized optical microscopy, and rheological measurements. With the hydroxyl group in the spacer, the critical micellization concentration of 12-3OH-12 was found to be lower than that of the homologue without hydroxyl (12-3-12) and the 12-3OH-12 molecules packed more densely at the air/EAN interface. It was then interesting to observe a coexistence of two separated phases at wide concentration and temperature ranges in this 12-3OH-12/EAN system. Such a micellar phase separation was rarely observed in the ionic surfactant binary system. With the increase of surfactant concentration, the reverse hexagonal and bicontinuous cubic phases appeared in sequence, whereas only a reverse hexagonal phase was found in 12-3-12/EAN system. But, the hexagonal phases formed with 12-3OH-12 exhibited lower viscoelasticity and thermostability than those observed in 12-3-12/EAN system. Such unique changes in phase behaviors of 12-3OH-12 were ascribed to their enhanced solvophilic interactions of 12-3OH-12 and relatively weak solvophobic interactions in EAN.

Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study.

The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration), they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp) and siRNA (21 bp). The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16). On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain).

Thermodynamics of self-assembling of mixture of a cationic gemini surfactant and sodium dodecylsulfate in aqueous solution: Calorimetry, conductivity and surface pressure measurements

The thermodynamics and phase behavior of mixtures of cationic gemini surfactant decanediyl-α,ω-bis(dodecyldimethylammonium bromide) (12-10-12) and sodium dodecylsulfate (SDS) were studied in the dilute SDS-rich region. The enthalpy of interaction between both surfactant monomers before the critical micelle concentration for the mixture (cmcmix) was determined by isothermal titration calorimetry (ITC). After the cmcmix, ITC results exhibited a first process associated with a large endothermic enthalpy change followed by a second one with a very small exothermic enthalpy change. In the same regions, the conductivity curves show an increase in slope after the break, followed by a plateau region, respectively for the two processes. The combined results from the various methodologies used lead us to propose that the first process reflects the formation of non-spherical micelles and the second one the vesicle formation. The area per catanionic complex was obtained through surface pressure measurements, leading to an apparent packing parameter ⩾1. The observed behavior may be rationalized on the basis of the hypothesis that both surfactants distribute asymmetrically in the vesicle bilayers and unevenly in the non-spherical micelle. In order to get structural information Cryo-TEM experiments were performed, which provided images that support this interpretation. From all the information gathered a phase diagram was mapped, including three one-phase regions of spherical micelles, non-spherical micelles and vesicles.