Quaternary Ammonium Gemini Surfactants Research Articles

Tuning the conformations of hemoglobin via interactions with single-chain and Gemini quaternary ammonium surfactants

The interactions between single-chain and Gemini surfactants with hemoglobin (Hb) were extensively investigated by UV–visible spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy (CD), isothermal titration calorimetry (ITC) and Zeta potential measurements. The results demonstrated that surfactants can destroy the hydrophobic cavity of Hb, and make the α-helical become loose and convert it into the β-sheet structure. The interactions between surfactants and Hb are mainly caused by electrostatic and hydrophobic interactions. The hydrophobic chain length and linking group length of surfactants have significant influence on tuning the conformations of Hb. The study provides a molecular basis for the applications of protein-surfactant complexes in biological, pharmaceutical, industrial and cosmetic systems.

Synthesis and Properties of Quaternary Ammonium Gemini Surfactants with Hydroxyethyl at Head Groups

AbstractA series of cationic gemini surfactants CmH2m + 1N+(CH2CH2OH)2(CH2)sN+(CH2CH2OH)2CmH2m + 1 2Br−, referred to as m‐s‐m (OH) (m = 8,10,12, s = 3,4), were prepared by quaternization of dihydroxyethyl tertiary amines with dibromoalkane. The dihydroxyethyl tertiary amines were synthesized by nucleophilic substitution of diethanolamine with bromoalkane. The characterization of the m‐s‐m (OH) surfactants was performed using 1H NMR and MS. The surface activities and aggregation behavior in aqueous solution of the m‐s‐m (OH) surfactants were studied using surface tension measurements, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The surface tension and critical micellar concentration of these surfactants in aqueous solution decreased dramatically due to the introduction of hydroxyethyl at the head group. The micelles and/or vesicles formed in the aqueous solution of m‐s‐m (OH) surfactants were strongly dependent upon the lengths of spacer chains and carbon chains. The number of vesicles increases and that of micelles decreases when the lengths of spacer chains and carbon chains increase.

Effects of Molecular Structure and Temperature on Micellization of Cationic Ammonium Gemini Surfactants in Aqueous Solution

AbstractMicellization of four cationic quaternary ammonium gemini surfactants, having a diethyl ether or hexyl spacer with the alkyl chain lengths of 12 and 16 carbon atoms, was studied using isothermal titration microcalorimetry (ITC) and electrical conductivity measurements in the temperature range from 298.15 to 313.15 K. In this temperature range, where surfactants are normally applied, the temperature almost does not influence the critical micelle concentration (CMC) and the degree of micelle ionization (α) values of the gemini surfactants, and the replacement of a hexyl spacer by a diethyl ether spacer leads to a slight decrease in the CMC and α values. However, as the alkyl chain length increases from 12 to 16 carbon atoms, the CMC values significantly decrease from 0.99–1.19 mM to 0.020–0.057 mM. In particular, the enthalpy of micellization (ΔHmic) and the associated thermodynamic parameters show obvious changes with varying temperature and molecular structure. ΔHmic becomes much more exothermic at higher temperature or for the surfactants with a more hydrophilic spacer. Moreover, the heat capacity change of micellization (ΔC P, mic) is less exothermic for the surfactants with a more hydrophilic spacer or a longer alkyl chain. The enthalpy–entropy compensation data show that the surfactants with longer alkyl chains have a more stable micellar structure.

Rheology of Quaternary Ammonium Gemini Surfactant Solutions: Effects of Surfactant Concentration and Counterions

AbstractTo prepare high‐performance clean fracturing fluids, cationic surfactants with a Gemini structure were synthesized as thickening agents. Distinct elastic characteristics at a sweep frequency of 0.1–10 Hz and shear resistance at high temperature were shown. Viscosity remained at about 150 mPa s after shearing for 60 min at 140 °C and 170 s−1. Stability investigation on cationic Gemini surfactant solution revealed that both viscosity and viscoelasticity were greatly affected by the surfactant concentration, temperature, and the amount of inorganic salt (potassium chloride). Complete formulation of a surfactant micelle structure in an aqueous solution requires a certain amount of time.

Green Synthesis, Surface Activity, Micellar Aggregation, and Corrosion Inhibition Properties of New Gemini Quaternary Ammonium Surfactants

A new series of gemini quaternary ammonium surfactants containing amide groups with the formula CnH2n+1CONH(CH2)2N+(CH3)2(CH2)2 N+(CH3)2(CH2)2NHCOCnH2n+1·2CH3CO3– (n = 11, 13, 15, 17) have been synthesized by the using green reagent dimethyl carbonate. The structures of these surfactants were confirmed by Fourier transform infrared spectroscopy, 1H NMR, 13C NMR, and mass spectra. Their surface activities and aggregation properties were investigated by surface tension, conductivity, steady-state fluorescence, dynamic light scattering, and transmission electron microscope measurements. The results show that these synthesized gemini quaternary ammonium surfactants reduce the surface tension of water to a minimum value of 28.21 mN·m–1 at a concentration of 0.256 mmol·kg–1 and self-assemble spontaneously into double layer aggregates which are mostly single-room vesicles and multilamellar vesicles. Furthermore, with increasing alkyl chain length, their critical micelle concentration values and the degree of cou...

Self-assembly of quaternary ammonium gemini surfactants in cyclohexane upon reinforcement by simple counterions.

The quaternary ammonium gemini surfactants 12-s-12 (s = 2, 6, and 10) can produce homogeneous cyclohexane solutions with the assistance of salts, sodium benzoate (NaBez), sodium salicylate (NaSal), or sodium 2-bromoethanesulphonate (NaBres). In these samples, 12-s-12/salt formed aggregates and their structures were assigned by SAXS measurements together with POM observations. Among the three salts, both NaBez and NaBres had similar effects on assisting aggregate formation, but NaSal favoured the generation of aggregates of 12-s-12 with lower interface curvature. For example, both 12-2-12/NaBez and 12-2-12/NaBres formed an I2 liquid crystalline (LC) phase with an Fm3m structure, but 12-2-12/NaSal generated a H2 LC phase. Both 12-6-12/NaBez and 12-6-12/NaBres generated a H2 LC phase, while 12-6-12/NaSal yielded both H2 and V2 phases with Pn3m symmetry, both of which co-existed in solution. The special effect of NaSal was attributed to its ortho-hydroxyl in the benzene ring. This favoured the formation of intermolecular hydrogen bonds among the NaSal molecules attracted to the quaternary ammonium head of 12-s-12. The water molecules joined between the NaSal molecules to build hydrogen-bonding bridges, which further increased the size of the 12-s-12 head. This benefited the formation of aggregates with lower surface curvature. In the systems of both NaBez and NaBres, the spacer length of the gemini surfactants dominated the morphology of the formed aggregates, wherein the effect of the salt was significantly weaker. Finally, the visco-elasticity of samples with similar aggregates was measured and the rheological behaviour discussed.

Benzene ring containing cationic gemini surfactants: Synthesis, surface properties and antibacterial activity

New quaternary ammonium gemini surfactants of the general formula CnH2n+1-Ph-NHCOCH2N+(CH3)2-(CH2)s-N+(CH3)2CH2CONH-Ph-CnH2n+1 (with n=8, 10, 12, 14, 16 and s=2, 4, 6) have been synthesized by an efficient synthetic pathway based on the quaternization of N,N,N′,N′-tetramethylalkylenediamine with 2-bromo-N-(4-(alkyloxy) phenyl) acetamides. Their surface properties were investigated by surface tension, electrical conductivity and dynamic light scattering (DLS) measurements. The study shows that the incorporation of a benzene ring in the hydrophobic tail prompts micelle formation which leads to a smaller cmc values in the range of 0.21–0.009mM compared to analogous geminis bearing alkyl hydrophobic chains. The length of the spacer and the hydrophobic chain has a pronounced effect on the aggregation behavior of surfactants molecules. This was confirmed by the average surfaces occupied by these molecules at the water–air interface calculated from the Gibbs equation. The size of the aggregates was measured by employing dynamic light scattering technique. The antimicrobial activity of investigated surfactants was evaluated against three microorganisms: Staphylococcus aureus, Escherichia coli and Candida albicans.

Quaternary Ammonium Gemini Surfactants Used in Enhanced Oil Recovery: Synthesis, Properties, and Flooding Experiments

AbstractIn this work, quaternary ammonium gemini surfactants with different spacers and lipophilic tails were synthesized by using imidazole and halogenated hydrocarbons as raw materials. The surfactants were characterized by EA, IR, and ESI-MS. Physico-chemical properties including critical micelle concentration (CMC), surface tension at CMC (γCMC), saturated adsorption amount (Γmax), occupied area per molecule (Amin), standard free energy of micellization (ΔG0m) and adsorption (ΔG0ads), as well as the oil/water interfacial tension were completely studied. The prepared surfactants could efficiently lower the interfacial tension at water/air interfaces and oil/water interfaces. The results indicate that the ability of reducing the surface tension was affected by the surfactant arrangement, which could be further adjusted by a spacer and lipophilic tail. Accordingly, four surfactants were chosen as the representatives to evaluate the displacement efficiency in flooding experiments via using the authentic sandstone microscopic model.

Three Gemini cationic surfactants based on polyethylene glycol as effective corrosion inhibitor for mild steel in acidic environment

Three Gemini quaternary ammonium surfactants based on polyethylene glycol have been prepared and characterized using FTIR and 1HNMR spectra. The effect of ethylene oxide units’ number on the steel corrosion in 1.0M HCl has been estimated using weight loss, polarization and electrochemical impedance spectroscopy. The Gravimetric technique has been done at three different temperatures 25, 40 and 55°C. The synthesized Gemini cationic surfactants with the higher molecular weight (higher number of ethylene oxide units) showed the higher inhibition efficiency under all conditions. All the prepared Gemini inhibitors showed higher inhibition efficiency upon raising the solution temperature from 25 to 55°C. The synthesized inhibitor G1500Br showed inhibition efficiency reach to 94% at temperature 55°C. The Langmuir adsorption isotherm is the best-fitted isotherm concerning the tested Gemini surfactants adsorption onto steel surface. The change in the free energy of adsorption refers to physicochemical adsorption on steel surface. The synthesized materials act as a mixed-type inhibitor based on the potentiodynamic polarization results.

Effects of a Spacer on the Phase Behavior of Gemini Surfactants in Ethanolammonium Nitrate.

The aggregation behavior of quaternary ammonium gemini surfactants (12-s-12) in a protic ionic liquid, ethanolammonium nitrate (EOAN), was investigated by small-angle X-ray scattering, freeze-fracture transmission electron microscopy, polarized optical microscopy, and rheological measurements. The rarely reported nonaqueous two phases in the ionic liquid were observed at lower 12-s-12 concentrations. The upper phase was composed of micelles, whereas only the surfactant unimers or multimers were detected in the low phase. At higher 12-s-12 concentrations, different aggregates were formed. The lamellar phase was observed in the 12-2-12/EOAN system, whereas the normal hexagonal phases in 12-s-12/EOAN (s = 3, 4, 5, 6, 8) systems and the micellar phase in the 12-10-12/EOAN system were observed. Such a dramatic phase transition induced by the spacer chain length was due to the unique solvent characteristics of EOAN compared to those of water and its counterpart ethylammonium nitrate.

The effect of hydroxyl on the solution behavior of a quaternary ammonium gemini surfactant.

The adsorption and viscoelastic properties of a micellar solution of 2-hydroxyl-propanediyl-1,3-bis(hexadecyldimethylammonium bromide), abbreviated as 16-3OH-16, have been investigated by surface tension and rheological measurements. Meanwhile, an aqueous solution of propanediyl-1,3-bis(hexadecyldimethylammonium bromide), abbreviated as 16-3-16, was also examined. From the steady state and oscillatory rheological results, a notable difference in shear viscosities between the two systems was observed. Zeta potentials and size distributions confirm the change in the potentials and hydrodynamic diameters, and these results are in good agreement with the rheological results. The differences of the two solutions were attributed to the effect of the hydroxyl group on the spacer of 16-3OH-16. Molecular dynamic simulations and density functional theory (DFT) calculations were performed to investigate the non-covalent interactions in the solution and the difference between the molecular orbitals and the electrostatic potentials. Our research shows that a more uniform distribution of positive charges around the spacer could result in a more effective electrostatic screening effect between the charged headgroups, and promote the formation of a worm-like micelle. Also, hyperconjugation becomes stronger when the hydroxyl group is introduced on the spacer of the gemini molecule.

Synthesis and properties of quaternary ammonium Gemini surfactants with hydroxyl groups

The article describes synthesis of four hydroxyethyl alkylene–double alkyl bromide through substitution of nucleophilic d iethanolamine, 1-bromododecane, and 1,4-dibromobutane. The structure of the new hydroxyl cationic surfactant (HDCS) was characterized by 1H NMR and FTIR spectra. The aqueous solution of HDCS showed critical micelle concentration, i.e., 5.6 × 10−2 mM, and could reduce oil/water interfacial tension to 3.28 × 10−3 mN m−1. The surface tension measurements provided a series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γCMC), adsorption efficiency (pC20), and effectiveness of surface tension reduction (ΠCMC). In addition, maximum surface excess concentration (Гmax) and minimum surface area/molecule (Amin) at the air/water interface were obtained by the Gibbs adsorption isotherm. The influence of inorganic salts (sodium chloride, calcium chloride) and organic salts (sodium benzoate) on the surface tension of HDCS in aqueous solution was investigated. For wettability alteration measurement, contact angle measurement as a quantitative method was utilized. Meanwhile, foam ability, foam stability, and emulsifying property of the synthesized surfactant were also examined at different concentration. HDCS also had excellent viscosity property.

Foams Stabilized by Fumed Silica Particles with a Quaternary Ammonium Gemini Surfactant

Foams Stabilized by Fumed Silica Particles with a Quaternary Ammonium Gemini Surfactant

Highly stable aqueous foams generated by fumed silica particles hydrophobised in situ with a quaternary ammonium gemini surfactant

Fumed silica hydrophobisedin situwith a quaternary ammonium gemini surfactant was an excellent stabiliser for aqueous foams.

Novel Synthesized Gemini Surfactant as Corrosion Inhibitor for Carbon Steel in HCl Solution

AbstractA quaternary ammonium gemini surfactant containing an ester spacer, namely (diethylhexanedioate)diyl‐α,ω‐bis(dimethyl myristyl ammonium bromide) (14‐DEHA‐14) was synthesized using a two‐step procedure with dimethyl hexanedioate, dimethylaminoethanol, and 1‐bromotetradecane. The chemical structure of the compound was confirmed by infrared (IR) spectrum, 1H nuclear magnetic resonance (NMR), and elemental analysis. The critical micelle concentration was determined by conductivity and tensiometry measurements, and its inhibition effect on corrosion of carbon steel in dilute (1.0 M) hydrochloric acid solution was investigated by weight loss measurements. The results show that the synthesized gemini surfactant acts as an excellent corrosion inhibitor in 1.0 M HCl solution. The adsorption of the inhibitor via chemical adsorption onto the carbon steel surface obeyed the Langmuir adsorption isotherm. A possible corrosion mechanism of the compound is discussed in relation to the calculated thermodynamic parameters and adsorption isotherm.

Synthesis and Properties of Alkyl Dibenzyl Ether Quaternary Ammonium Gemini Surfactant

Abstract Three gemini surfactants with dibenzyl ether spacer (10-B-10, 12-B-12, and 14-B-14) were synthesized and characterized. The surface activity and thermodynamic properties of micellization were determined by surface tension, steady-state fluorescence microscopy, and conductivity methods. The thermodynamic parameters of micellization (ΔmicG0, ΔmicH0, and ΔmicS0) derived from the electrical conductivity measurement implied that the micellization of these surfactants was driven by enthalpy. The enthalpy–entropy compensation of micellization showed that the stability of micelles increased with increasing alkyl chain length. Finally, we evaluated the effects of alkyl chain length on the interfacial tension, foam ability, and the emulsion stability.

Synthesis of some quaternary ammonium gemini surfactants and evaluation of their performance as corrosion inhibitors for carbon steel in oil well formation water containing sulfide ions

Three quaternary ammonium gemini surfactants were synthesized, characterized, and evaluated as corrosion inhibitors for carbon steel in oil well formation water containing sulfide ions.

Synthesis and Micellization of Organosilicon Gemini Quaternary Ammonium Surfactants

AbstractA novel class of organosilicon gemini quaternary ammonium surfactant alkyl‐α, ω‐bis(diethyl‐methyl‐dimethoxy‐silopropyl ammonium bromide) (α, ω = 1,4; 1,6; 1,8) was synthesized and characterized by 1H‐nuclear magnetic resonance (NMR) and elemental analysis. It is found that the quaternization reaction has two steps: first single quaternization and then double quaternization. The effect of solvent on convert ratio has the following sequence: polar aprotic solvents > polar protic solvents > aromatic solvents. The electrical conductivity of aqueous solution was measured at 20, 25, 30 and 35 °C, and the thermodynamic properties of , and were calculated according to the mass action model and Gibbs equation. It is shown that the enthalpy driven and entropy driven are almost equal in the micellization of [SiC3‐4‐SiC3]Br2 and [SiC3‐6‐SiC3]Br2, but in the micellization of [SiC3‐8‐SiC3]Br2, the enthalpic contribution becomes significant and the effect of thermal is greater than the degree of order in the micellization.

Micellization Parameters of Six Gemini Quaternary Ammonium Surfactants from Measurements of Conductivity and Surface Tension

The micellization of six Gemini quaternary ammonium surfactants aqueous solutions has been investigated from measurements on specific conductivity as a function of surfactant concentration at different temperatures from (298.15 to 323.15) K. The micellization parameters such as the critical micellar concentration (CMC) and the degree of counterion dissociation (β), Gibbs free energy (ΔGmic), enthalpy (ΔHmic), and entropy (ΔSmic) of micellization are then obtained. It is shown that the conductometry measurements provide agreement of the CMC values at 298.15 K with the surface tension studies. With the rise of temperature, the values of CMC and β increase, while ΔGmic changes little. The linear plots of TΔSmic versus ΔHmic show the effects of enthalpy–entropy compensation. The length of alkyl chain and the spacer group of the Gemini surfactant have significant influences on micellization parameters.

Self-aggregation properties of new ester-based gemini surfactants and their rheological behavior in the presence of cosurfactant — monolaurin

A series of new quaternary ammonium gemini surfactants having different ethylene oxide (EO) units as spacer linked with ester functionality have been synthesized and characterized. The self-aggregation and thermodynamic properties of these new gemini surfactants have been investigated in respect to the effect of increasing ethylene oxide spacer units. The critical micelle concentration increases with increase in EO spacer units and other surface properties have been found to be dependent on the length of EO spacer units. Micellar solutions of these surfactants demonstrated greater ability to solubilize a large amount of nonionic amphiphile monolaurin (ML) at 25°C. An addition of ML to the aqueous solutions of these surfactants in a dilute region reduces the micellar curvature to less positive and favors sphere to rod to transient networks (a transparent solution of viscoelastic wormlike micelles). Viscosity increases by three orders of magnitude of that of pure solvent. The rheology study shows that the length of the polar EO spacer units of these surfactants affects the rheology; the maximum viscosity is achieved with gemini surfactant/H2O/ML having single EO unit as spacer and regular decrease in viscosity is observed with increase in EO spacer units for gemini surfactant/H2O/ML system. These systems exhibit viscoelastic behavior described by the Maxwell mechanical model with a single stress relaxation mode.