Properties of two polymerisable surfactants aqueous solutions: dodecylethylmethacrylatedimethylammonium bromide and hexadecylethylmethacrylatedimethylammonium bromide. II. Partial molar volume and micelle hydration

The partial molar volume and hydration number of two micellised polymerisable surfactants (dodecylethylmethacrylatedimethylammonium bromide (C₁₂PS) and hexadecylethylmethacrylatedimethylammonium bromide (C₁₆PS)) were determined. Results support marginally the annular conformation of the polar head group (N⁺(CH₃)₂-CH₂-CH₂-O-CO-C(CH₃)(=CH₂)) proposed in the literature.     

Physicochemical properties of α, ω-type bolaform surfactant in aqueous solution. Eicosane-1,20-bis(triethylammonium bromide)

The physicochemical properties of the, - type (bolaform) surfactant, eicosane-1, 20-bis(triethylammonium bromide) (C₂₀Et₆), in aqueous solution have been investigated by means of surface tension, electrical conductivity, dye solubilization, and time-resolved fluorescence quenching (determination of average micelle aggregation number). Using electrical conductivity, the critical micelle concentration of C₂₀Et₆ was found to be 6.0×10^–3 mol dm^–3 and the ionization degree of C²⁰Et₆ micelle was found to be 0.42. From surface tension measurments, the molecular area of C₂₀Et₆ at the air-water interface was about twice that of normal type surfactants such as dodecyltrimethylammonium bromide (DTAB). The solubilizing power of micellar solution of C₂₀Et₆ toward Orange OT was 1.0×10^–2 mole of dye per mole of surfactant, i. e., slightly smaller than that of DTAB. The micelle aggregation number,N, was found to be 17±2 by time-resolved fluorescence quenching. C₂₀Et₆ showed a very small temperature dependence ofN, much less than for normal surfactants.     

Surface and volume properties of dodecylethyldimethylammonium bromide and benzyldimethyldodecylammonium bromide: II. Volumetric properties of dodecylethyldimethylammonium bromide and benzyldimethyldodecylammonium bromide

Density measurements were carried out for aqueous solutions of two cationic surfactants: dodecylethyldimethylammonium bromide (C₁₂(EDMAB)) and benzyldimethyldodecylammonium bromide (BDDAB). On the basis of the obtained results of the measurements the CMC and partial molar volumes of the surfactants studied were also determined. The obtained CMC values were also analyzed with those accounted on the basis of the surface tension data from the previous paper [J. Harkot, B. Jańczuk, J. Colloid Interface Sci. (2008), submitted for publication]. The values of CMC determined from the surface tension and density measurements for C₁₂(EDMAB) are equal to 9.9×10⁻³ and 1.5×10⁻² M and for BDDAB to 5.25×10⁻³ and 5.3×10⁻³ M, respectively. These obtained values are very similar. However, in the literature it is difficult to find the CMC values for C₁₂(EDMAB) and BDDAB determined by these two methods used by us—especially from the density measurements for BDDAB and surface tension measurements for C₁₂(EDMAB). In the case of the apparent molar volumes of C₁₂(EDMAB) there is a good agreement between the values obtained by us and those found in the literature. The CMC values for C₁₂(EDMAB) and BDDAB were also determined on the basis of their surface tension and free energy of electrostatic interactions between the polar heads of these surfactants and compared with those obtained from the surface tension and density measurements. It was found that the theoretically obtained CMC values were close to those determined from the density and surface tension data for the C₁₂(EDMAB) and that the ratios of the CMC values of the surfactants to their concentration at which the water surface tension decreased by about 20 mN/m proved that the presence of the aryl group in the BDDAB head instead of the methyl group caused that its micellization process was more inhibited in relation to its adsorption at air–water interface than that of C₁₂(EDMAB).     

Surfactant ion electrode measurements of sodium alkylsulfate and alkyltrimethylammonium bromide micellar solutions

EMF measurements in water at 25°C have been made using surfactant ion and counterion electrodes on two homologous series of long chain surfactants, the sodium alkylsulfates (R=n-C₈H₁₇ to n-C₁₄H₂₉) and the alkyltrimethylammonium bromides (R=C₁₀H₂₁ to C₁₆H₃₃). The data show evidence of association below the critical micelle concentration (CMC) but not of micelle ordering due to coulombic repulsion above this concentration.     

Interaction between biosurfactant surfactin and cationic surfactant cetyl trimethyl ammonium bromide in mixed micelle

An anionic/cationic mixed surfactant aqueous system of surfactin and cetyl trimethyl ammonium bromide (CTAB) at different molar ratios was studied by surface tension and fluorescence methods (pH 8.0). Various parameters that included critical micelle concentration (cmc), micellar composition (X ₁), and interaction parameter (β ^m) as well as thermodynamic properties of mixed micelles were determined. The β ^m was found to be negative and the mixed system was found to have much lower cmc than pure surfactant systems. There exits synergism between anionic surfactin and cationic CTAB surfactants. The degree of participation of surfactin in the formation of mixed micelle changes with mixing ratio of the two surfactants. The results of aggregation number, fluorescence anisotropy, and viscosity indicate that more packed and larger aggregates were formed from mixed surfactants than unmixed, and the mixed system may be able to form vesicle spontaneously at high molar fraction of surfactin.     

Mixed Micellization Behavior of 12-2-12 Gemini Surfactant with Some Alkyltrimetyl Ammonium Bromide Surfactants

Mixed micellization behavior of dimeric cationic surfactant ethanediyl-1,2-bis (dimethyldodecylammonium bromide) (12-2-12) with a series of monomeric cationic surfactants dodecyltrimethyl ammonium bromide (DTAB), tetradecyltrimethyl ammonium bromide (TTAB), and cetyltrimethyl ammonium bromide (CTAB) has been studied in aqueous and aqueous polyvinylpyrrolidone (PVP) solutions at 298.15, 308.15, and 318.15 K, respectively, using conductometric method. Various thermodynamic parameters like mixed micelle concentration (C_m), micelle mole fraction (X₁), interaction parameter (β), and free energy of mixing (ΔG_ex) of the mixed systems have been determined and analyzed using Rubingh's regular solution theory. The results indicate that in aqueous solutions the binary mixtures of 12-2-12 with DTAB/TTAB behave nonideally with mutual synergism whereas that with CTAB shows almost ideal behavior at 298.15 K. At 318.15 K, all these binary mixtures exhibit antagonistic behavior. The effect of variation in chain length of alkyltrimethyl ammonium bromide surfactants on the interactions with 12-2-12 have also been evaluated and discussed.     

Effect of imidazolium-based ionic liquids on the aggregation behavior of twin-tailed cationic gemini surfactant in aqueous solution

Micellization behavior of the twin-tailed surfactants can be modulated by the addition of various modifiers. Ionic liquids (ILs) are one of them and are documented here. The beauty of these environmentally benign neoteric molecules lies in their structural versatility. Here, we have investigated the effect of three ILs: 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]), 1-hexyl-3-methylimidazolium bromide ([C₆mim][Br]), and 1-octyl-3-methylimidazolium bromide ([C₈mim][Br]) on the aggregation and surface adsorption behavior of cationic gemini surfactant, bis(hexadecyldimethyl ammonium)propane dibromide (16-3-16) through experimentally measured electrical conductivities, surface tensions, and by spectral methods (UV-vis absorbance and fluorescence measurements). The main focus of the study is to observe the effect of added ILs on the critical micelle concentration (cmc), various surface parameters, aggregation number, and size of the aggregates of gemini surfactant. The results show that the more hydrophobic ILs, that is, [C₆mim][Br] and [C₈mim][Br] behave as electrolyte at lower concentration and cosurfactant at higher concentration, whereas moderately hydrophobic IL [C₄mim][Br] acts as an electrolyte at all concentration ranges studied. The modulating effects of ILs were also compared with conventional electrolyte (NaBr) at similar conditions.     

Effect of cationic surfactant cetyltrimethylammonium bromide on the enzymatic hydrolysis of cellulose

Effect of cationic surfactants alkyltrimethylammonium bromide (C_nTAB) with varied alkyl chain lengths on the enzymatic hydrolysis of Avicel and the surface charge of cellulase was investigated. Enzymatic hydrolysis of Avicel increased linearly from 42.1 to 61.4 % with the increase of the concentration of cetyltrimethylammonium bromide (C₁₆TAB) logarithmically from 0.0001 to 0.01 mM, and reached a maximum value at the concentration of 0.01–0.03 mM. When the concentration was increased further, the cellulase solution became positively charged and the enzymatic hydrolysis of Avicel decreased rapidly. With the increasing alkyl chain length, C_nTAB provided more proton and neutralized the negative charge of cellulase more obviously. Therefore, the required concentration of C_nTAB could be less to enhance the enzymatic hydrolysis of Avicel. In addition, C₁₆TAB could enhance enzymatic hydrolysis efficiency of corncob at high solid content from 35.0 to 56.3 %; C₁₆TAB could reduce about 60 % of the cellulase loading in the enzymatic hydrolysis of corncob to obtain the same glucose yield. Effect of C₁₆TAB on the enzymatic hydrolysis of typical pretreated softwood and hardwood was also investigated. This study laid the foundation for using C_nTAB to recover cellulase, and provided the design direction for cellulase with higher activity and better stability by adjusting its hydrophilicity and chargeability.     

Flow-injection chemiluminescence method for determination of critical micelle concentration of surfactants

In this study, chemiluminescence (CL) behaviour of Luminol-H₂O₂ in the presence of the different concentrations of four surfactants, cetyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB), sodium dodecyl sulphate (SDS) and polyoxyethylene dodecyl ether (Brij-35), was investigated. A novel method for the direct determination of critical micelle concentration (CMC) of the surfactants using flow-injection CL is described. Under the optimum conditions, the luminescence intensity of the Luminol-H₂O₂ system increased gradually with increasing concentration of the surfactants before the CMC, but rapidly reached to the emission maximum at the CMC, followed by a decrease after the CMC. The concentrations of the surfactants corresponding to the luminescence maximum are in agreement with the literature CMC values. The main factors affecting the determination of CMC are discussed. The mechanistic studies show that the luminescence peaks observed in the experiment were mainly because of the protective effect of the micelle against the transition of the excited species and the retarding effect of the micelle structures on the CL reaction rate.     

Synthesis and Performance of Novel Sulfonate Gemini Surfactant with Trialkyl Chains

A new type of sulfonate gemini surfactant with three lipophilic alkyl chains (3C₁₀-DS) was synthesized, and the structure of the product was confirmed by using the infrared spectrum and mass spectrum. Its critical micelle concentration (CMC) is 0.41 mmol/L, one order of magnitude lower than those of convectional (single-chain) surfactants, and the minimum surface tension is 27.6 mN/m. The interfacial tension (IFT) between the compound system of 3C₁₀-DS and petroleum sulfonate (PS) and the simulated oil reaches ultra-low levels (10^?3 mN/m), and there exists significant synergistic effect between 3C₁₀-DS and PS. The compound flooding system consisting of polymer and the mixture of 3C₁₀-DS and PS can effectively improve oil recovery for high-medium permeability cores and have a good application prospect in enhancing oil recovery.     

Micelle formation by N-alkyl-N-methylpyrrolidinium bromide in ethylammonium nitrate

The aggregation behavior of long-chain pyrrolidinium ionic liquids, N-alkyl-N-methylpyrrolidinium bromide (C_nMPB, n = 12, 14, and 16) was investigated by surface tension measurements in a protic room temperature ionic liquid, ethylammonium nitrate (EAN), at various temperatures. A series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), effectiveness of surface tension reduction (Π_CMC), maximum surface excess concentration (Γ_max), and the area occupied per surfactant molecule at the air/solution interface (A_min) were estimated. From these parameters, we demonstrated that the surface activity of C_nMPB is much lower in EAN than that in water. Comparing C_nMPB with alkylimidazolium bromides and alkylpyridinium bromides, the effect of the cationic group on micellization in EAN was also investigated. The thermodynamic analysis of micellization revealed that the micelle formation process for C_nMPB (n = 12, 14, and 16) is entropy-driven at low temperature and enthalpy-driven at high temperature. The micelle aggregation number estimated from the ¹H NMR data is about 21 for C₁₂MPB in EAN, which is much less than that in water. The results of the surface tension measurements and ¹H NMR spectra indicate that the [CH₃CH₂NH₃]⁺ cations of EAN exist around the head groups of C_nMPB when micelles are formed and the NO₃⁻ ions are adsorbed at the micelle surface.     

Synthesis and Surface Activity of Anionic Gemini Surfactants with Alkyl Spacers

A series of anionic Gemini surfactants called alkanediyl-α,ω-bis(m-octylphenoxy sulfonate) with different length of (CH₂)_x spacer, C₈C_xC₈ (x = 2, 4, 6, 8), have been synthesized from 4-n-octylphenol and their basic physicochemical properties are investigated. The results indicate that they are different from cationic Gemini surfactants called alkanediyl-α,ω-bis(dimethyldodecylammonium bromide), 12-(CH₂)_s-12, in the literature. It is found that as the carbon atom number of the spacer increases, the cmc (critical micelle concentration) decreases gradually, and the surface area per molecule (A_min) decreases initially and then increases. The breakpoints appear at number 4 of carbon atom in the spacer. Though the length of the spacer is different for the Gemini surfactants from C₈C₂C₈ to C₈C₆C₈, there is no obvious change on the micropolarity.     

Volumetric Studies on Aqueous Solutions of Dodecyltrimethylammonium Bromide and 1-Dodecyl-3-methylimidazolium Bromide

The densities of aqueous solutions of mixed surfactants of dodecyltrimethylammonium bromide and 1-dodecyl-3-methylimidazolium bromide (DTAB/C₁₂mimBr) were measured at various compositions. The concentration dependent apparent molar volumes of these mixed surfactants were calculated and used to deduce the critical micelle concentrations (cmc) and the apparent molar volumes in the micelles and the continuous phase. The one-parameter Margules equation was applied to correlate the composition dependent cmc values and to obtain the activity coefficients and mole fractions of these surfactants in the mixed micelles, which were further used to calculate the excess Gibbs energies and the excess volumes. It was found that the excess Gibbs energies and the excess volumes of the mixed micelles are all negative, indicating that these mixed micelles are more stable and packed more tightly than their corresponding pure micelles.     

Dynamic light scattering study of cetyltrimethylammonium bromide aqueous solutions

Cetyltrimethylammonium bromide (CTAB) aqueous solutions are studied by dynamic light scattering method in a wide concentration range covering the first and second critical micelle concentrations (CMC₁ and CMC₂, respectively). Nonmonotonic and ambiguous behavior of diffusion coefficients D with an increase in concentrations above CMC1 is revealed. An increase in the D values in the first decade of CTAB concentration above CMC1 agrees with known published data for aqueous solutions of ionic surfactants. It is shown that an increase in the ionic strength of solution with the addition of KBr leads to a decrease in the positive slope of the dependence of diffusion coefficients on CTAB concentration up to zero at 0.05 M KBr. Two relaxation processes corresponding to large and small D values are simultaneously observed in micellar solutions, beginning with 0.03 M CTAB concentration. The data obtained are compared with published data, as well as with the results of viscosity measurements. The performed analysis indicates that the observed relaxation processes are explained by the coexistence of spherical and nonspherical micelles. It is established that micelles acquire a cylindrical shape at CTAB concentrations ranging from 0.2 to 0.25 M. Hydrodynamic radii and lengths of micelles are calculated.     

Surface and thermodynamic studies of N-((octyl, dodecyl, and cetyl) oxycarbonylmethyl) pyridinium bromide

Summary N-Octyloxycarbonylmethyl pyridinium bromide (C ₈), N-dodecyloxycarbonylmethyl pyridinium bromide (C ₁₂) and N-cetyloxycarbonylmethyl pyridinium bromide (C ₁₆) were prepared. Several studies were carried out with their aqueous solutions. Surface tensions, electrical conductivities, and biodegradabilities were evaluated. The antibacterial and antifungal activities of the cationic surfactants were studied. Surface properties, particularly critical micelle concentration (CMC), effectiveness ( _CMC ), efficiency (P _c20), maximum surface excess (_max), and minimum surface area (A _min) were investigated at different concentrations at 20, 35, and 50°C respectively. Free energies, enthalpies, entropies of micellization, and adsorption of the surfactants in the aqueous solution were studied.

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Untersuchung der Thermodynamik und der Oberflächeneigenschaften von N-((Octyl-, Dodecyl- und Cetyl)oxycarbonylmethyl)-pyridiniumbromid

Zusammenfassung Verschiedene Untersuchungen an wäßrigen Lösungen von N-Octyloxycarbonylmethyl-pyridiniumbromid (C ₈), N-Dodecyloxycarbonylmethyl-pyridiniumbromid (C ₁₂) und N-Cetyloxycarbonylmethyl-pyridiniumbromid (C ₁₆) wurden durchgeführt. Oberflächenspannungen, elektrische Leitfähigkeiten und biologische Abbaubarkeit wurden bestimmt. Die bakterizide und fungizide Aktivität der kationischen Tenside wurde untersucht. Oberflächenparameter, insbesondere kritische Micellenkonzentration (CMC), Effektivität (CMC), EffizienzP _c20), maximaler Oberflächenüberschuß (_max) und minimale Oberfläche (A _min) wurden bei verschiedenen Konzentrationen und bei Temperaturen von 20, 35 und 50°C untersucht. Die freien Energien, Enthalpien, Entropien und die Asorption der Tenside in wäßriger Lösung wurden bestimmt.

     

Micellization behavior of the ionic liquid lauryl isoquinolinium bromide in aqueous solution

The micellization behavior of the ionic liquid lauryl isoquinolinium bromide ([C₁₂iQuin]Br) in aqueous solution has been assessed using surface tension, electrical conductivity, and ¹H nuclear magnetic resonance (NMR) measurements. The results reveal that the critical micelle concentration (CMC) and constant surfactant tension (γ _cac) are lower than that of butyl isoquinolinium bromide ([C₄iQuin]Br), octyl isoquinolinium bromide ([C₈iQuin]Br, and lauryl pyridinium bromide ([C₁₂Pyr]Br). ¹H NMR spectra show the evidence of paralleled π-stacking of adjacent isoquinoline rings. To elucidate the effect of the π–π interactions on the aggregation process, thermodynamic parameters such as the standard free energy, enthalpy, and entropy of aggregation have been discussed. These parameters are evaluated from the CMC with temperature by fitting these values to expressions derived from a micellization thermodynamic model. The enthalpy–entropy compensation phenomenon has been observed in the micellization process of [C₁₂iQuin]Br in water, and the presence of isoquinoline cations is responsible for the decrease in the ΔH _mic ^? , compared with [C₁₂Pyr]Br which has the same alkyl chain and counter-ion.     

Aggregation behaviour and thermodynamics of mixed micellization of 1-hexadecylpyridinium bromide and ionic liquid in ethylene glycol/water binary mixtures

Micellar behavior of binary combinations of ionic liquid, 1-tetradecyl-3-methylimidazolium bromide, with conventional cationic surfactant 1-hexadecylpyridinium bromide was investigated by means of conductometry to study the effect of cosolvent and water content and temperature. The critical micelle concentration and the degree of counterion association were calculated from the conductometry data. Thermodynamic parameters were obtained from the temperature dependence of the critical micelle concentration. The standard Gibbs energy of micellization increased with the increasing percentage of cosolvent as well as the mole fraction of C₁₄mimBr. The standard enthalpy and standard entropy of micelle formation were both decreased with the increasing temperature and the concentration of cosolvent. The entropy contribution was larger than the enthalpic one in pure water, whereas in the ethylene glycol/H₂O mixture the enthalpy contribution was predominant     

Using Calixarenes To Model Polyelectrolyte Surfactant Nucleation Sites

The formation of mixed micelles composed of dodecyltrimethylammonium bromide (C₁₂TAB) and a hexamethylated p‐sulfonatocalix[6]arene (SC6HM) was studied by several techniques. It was found that above the critical aggregation concentration the concentrations of free and micellized surfactant are strongly related to that of SC6HM. When there is free SC6HM in solution, the addition of C₁₂TAB mainly results in an increase in the concentration of micellized surfactant, but when all SC6HM has been aggregated, the addition of C₁₂TAB results in a substantial increase in the concentration of free surfactant in solution. When the concentration of free surfactant is equal to the critical micelle concentration of the pure system, a second independent aggregation process is observed. This aggregation behavior has many features that are similar to those of more complex systems that involve surfactants in the presence of oppositely charged polyelectrolytes. In this way, calixarenes can serve as simple models to mimic polyelectrolytes and to gain insight into the complex behavior displayed by these macromolecules.     

Synthesis,surface activity,and corrosion inhibition of dentritic quaternary ammonium salt-type tetrameric surfactants

The dentritic quaternary ammonium salt-type tetrameric surfactant (4C₁₂tetraQ) was synthesized, and the molecular structure was confirmed by ¹H NMR and FTIR. The surface activity of 4C₁₂tetraQ was investigated by surface tension, and surface chemical parameters, such as critical micelle concentration (cmc), efficiency (pC₂₀), effectiveness (π_cmc), the surface tension value at cmc (γ_cmc), minimum surface area (A_min), maximum surface excess (Γ_max), and cmc/C₂₀ were obtained from the measurement results. The results show that the 4C₁₂tetraQ surfactant has higher surface activity than the traditional monomeric surfactants (dodecyl trimethyl ammonium bromide, DTAB). The Krafft points were taken as <0°C, indicating that the synthesized tetrameric surfactants had good water solubility. Free energies of micellization and adsorption show that 4C₁₂tetraQ display greater propensity to absorb at the interface than form micelle in the bulk of the aqueous solution, and that the two processes are spontaneous. The measurement results show that 4C₁₂tetraQ has good emulsification power and foam performance. The corrosion efficiency was evaluated with the loss weight method in 1?mol/L HCl solution, and the results show that the 4C₁₂tetraQ surfactant has good corrosion inhibition, and can be considered as a corrosion inhibitor.     

Hemiesters and hemiamides of maleic and succinic acid: synthesis and application of surfactants in emulsion polymerization with styrene and butyl acrylate

Hemiesters and hemiamides of maleic acid with different chain lengths of the hydrophobic alkyl group (R = C₈H₁₇, C₁₀H₂₁, C₁₂H₂₅, C₁₆H₃₃) have been synthesized and used as surfactants in the emulsion polymerization of styrene and butyl acrylate. The same polymerization experiments were also carried out using nonreactive surfactants with an analogous succinic structure. The chemical structure of the surfactants was confirmed by 1H nuclear magnetic resonance. The melting point and critical micelle concentration of the reactive surfactants described herein were measured. All of the surfactants studied provided good stability of styrene/butyl acrylate latexes, when compared with a reference latex of a styrene/butyl acrylate copolymer prepared with a surfactant sodium dodecyl sulfate. The amount of surfactant grafted onto the particles of the final latex was estimated by conductimetric titration. Between 33 and 68% of surfactant used in emulsion polymerization was found on the surface of latex particles. Electrolyte addition at high concentration and freeze/thaw cycle cause flocculation of latexes. Copyright © 1999 John Wiley & Sons, Ltd.