Tetradecyltrimethylammonium Chloride Research Articles

Analysis of TOF-SIMS spectra using quaternary ammonium ions for mass scale calibration

A novel method with quaternary ammonium salts as internal additives has been applied to the mass scale calibration of time-of-flight secondary ion mass spectrometry (TOF-SIMS). Five kinds of quaternary ammonium salts, octyltrimethylammonium bromide (C8TMA), tetradecyltrimethylammonium chloride (C14TMA), octadecytrimethylammonium chloride (C18TMA), cetylpyridinium chloride (CPC) and benzyldimethyltetradecylammonium chloride (Bzl) were diluted with distilled water and conc-NH3 and were mixed in equal quantities. The solution was added to Tinuvin 770 coated on a Si wafer. Then, the sample was measured by TOF-SIMS. The relation between the relative mass accuracy of molecular ions of Tinuvin 770 and the combinations of ions selected for the mass scale calibration was investigated. To improve the mass accuracy of the molecular ion of Tinuvin 770, ions should be selected for the mass scale calibration in the following two ways: one way is for ions to consist only of molecular ions of C8TMA, C14TMA and C18TMA, and the other way is for ions to include the molecular ion of C18TMA, along with the CXHY fragment ions. These results support the proposition of ISO 13084. The novel method with internal additives is effective to improve the mass accuracy of high-mass ions. Quaternary ammonium salts are potential candidates of internal additives.

Flotation and adsorption of quaternary ammonium salts collectors on kaolinite of different particle size

The flotation behaviors of decyltrimethylammonium (103C), dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC) and cetyltrimethylammonium chloride (CTAC) on kaolinite of different particle size fraction were studied. The adsorbed amount and adsorption isotherms of collectors on kaolinite were determined for painstaking investigation into the adsorption of quaternary amines at kaolinite–water interface by ultraviolet spectrophotometer methods. The flotation results show that the flotation recovery of kaolinite of different particle fraction increases with an increase in pH when 103C, DTAC, TTAC and CTAC are used as collectors. As the concentration of collectors increases, the flotation recovery increases. Particle size of kaolinite has a strong effect on flotation. The flotation recovery of fine kaolinite decreases with the carbon chain of quaternary ammonium salts collectors increasing, while coarse kaolinite is on the contrary. The adsorbed amount tests and adsorption isotherms show that adsorbed amount increases when the particle size of kaolinite increases or when the carbon chain length of quaternary ammonium salts increases. Within the range of flotation collector concentration, the longer the hydrocarbon chain, the more probable to be absolutely adsorbed by fine kaolinite particles and then the lower the collector concentration in the bulk, which leds to lower flotation recovery.

Influence of the alkyl chain length, temperature, and added salt on the thermodynamics of micellization: Alkyltrimethylammonium chlorides in NaCl aqueous solutions

The thermodynamics of micelle formation of the cationic surfactants decyltrimethylammonium chloride (DeTAC) and tetradecyltrimethylammonium chloride (TTAC) in water and aqueous NaCl solutions have been investigated. Isothermal titration calorimetry (ITC) was used to study the effect of added salt on the critical micelle concentration, cmc, and enthalpy of micellization, Δ mic H ∘ , between the temperatures (278.15 and 328.15) K. From the temperature dependence of Δ mic H ∘ , the heat capacities of micellization, Δ mic c p ∘ , were determined. The results obtained are compared with reported data for dodecyltrimethylammonium chloride (DTAC). The values of Δ mic c p ∘ are negative for all surfactants in all solvents relating to the removal of water accessible non-polar surfaces also in the presence of excess counterions. The temperature dependence of Δ mic c p ∘ is evident at DeTAC, leading to the assumption that, especially at high temperatures, the non-polar parts of surfactant molecules are still in perceivable contact with water.

Separation of complex mixtures of fluorobenzoic acids by capillary electrophoresis

Fluorobenzoic acids are important intermediates in the synthesis of antibacterial drugs. Conditions for the separation of mixtures of twenty-five acids by CE have been optimized. A set of conditions with phosphate buffer (pH 3.1), successive multiple ionic-polymer layer (SMIL) coating capillary, and negative separation voltage provided a short time separation based on the difference in the acidic dissociation constant (pK(a)) of the sample acids. Addition of ACN to the separation solution improved the selectivity resulting in a broader distribution of migration times of the samples. The addition of tetradecyltrimethylammonium chloride below the CMC was also effective in changing the migration pattern of fluorobenzoic acids. Furthermore, practical utility was demonstrated through quantitative studies on the optimized condition including the durability of the SMIL coating.

Interpretation of Conductivity Results from 5 to 45 °C on Three Micellar Systems below and above the CMC

Electrical conductivity has been used at different temperatures to study three micellar systems: tetradecyltrimethylammonium chloride (TTACl), dodecyltrimethylammonium chloride (DTACl), and decyltrimethylammonium chloride (DeTACl). A phenomenon of premicellization is observed for DeTACl and DTACl below the critical micellar concentration (CMC). Association constants are introduced in the MSA-transport theory to correctly reproduce experimental conductivity and also calculate the effective charge of the micelles and their degree of dissociation. Various mechanisms are considered to explain premicellization. The formation of a neutral pair followed by an association involving two monomers and a counterion appears to be the most probable first step in the premicellization process.

Modulation of Photo-oxidative DNA Damage by Cationic Surfactant Complexation

The natural packaging of DNA in the cell by histones provides a particular environment affecting its sensitivity to oxidative damage. In this work, we used the complexation of DNA by cationic surfactants to modulate the conformation, the dynamics, and the environment of the double helix. Photo-oxidative damage initiated by benzophenone as the photosensitizer on a plasmid DNA complexed by dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC), cetyltrimethyammonium chloride (CTAC) and bromide (CTAB) was detected by agarose gel electrophoresis. By fluorescent titration in the presence of ethidium bromide (EB) and agarose gel electrophoresis, we experimentally confirmed the complexation diagrams with a critical aggregation concentration on DNA matrix (CAC DNA) delimiting two regions of complexation, according to the DNA-phosphate concentration. The study of the photo-oxidative damage shows, for the first time, a direct correlation between the DNA complexation by these surfactants and the efficiency of DNA cleavage, with a maximum corresponding to the CAC DNA for DTAC and CTAC, and to DNA neutralization for CTAC and CTAB. The localization of a photosensitizer having low water solubility, such as benzophenone, inside the hydrophobic domains formed by the surfactant aggregated on DNA, locally increases the photoinduced cleavage by the free radical oxygen species generated. The inefficiency of a water-soluble quencher of hydroxyl radicals, such as mannitol, confirmed this phenomenon. The detection of photo-oxidative damage constitutes a new tool for investigating DNA complexation by cationic surfactants. Moreover, highlighting the drastically increased sensitivity of a complexed DNA to photo-oxidative damage is of crucial importance for the biological use of surfactants as nonviral gene delivery systems.

Micellar behavior of aqueous solutions of dodecyldimethylethylammonium bromide, dodecyltrimethylammonium chloride and tetradecyltrimethylammonium chloride in the presence of α-, β-, HP β- and γ-cyclodextrins

Conductivity, static fluorescence and 1H NMR measurements have been carried out to study the micellar behavior of aqueous solutions of dodecyldimethylethylammonium bromide (DDAB), dodecyltrimethylammonium chloride (DTAC) and tetradecyltrimethylammonium chloride (TDAC) in absence and presence of α-cyclodextrin ( α-CD), β-cyclodextrin ( β-CD), hydroxypropyl- β-cyclodextrin (HP β-CD) and γ-cyclodextrin ( γ-CD). The conductivity measurements were carried out at 298.15 K. The influence of cyclodextrins on the micellar parameters, such as cmc ∗ (apparent critical micellar concentration), β (degree of ionization) have been analyzed. Thermodynamics of the systems was discussed in terms of the change in standard free energy of micellization, Δ G m 0 . Micellization was found to be less spontaneous in presence of cyclodextrins. The fluorescence intensity of the surfactant solutions is enhanced by the addition of cyclodextrins. The association constants obtained from conductivity and fluorescence data suggest the binding of γ-CD with the surfactants to be strongest among all the cyclodextrins used. 1H NMR chemical shift changes provide powerful means for probing the cyclodextrin–micellar interactions and inclusion of surfactant is shown by the change in the chemical shift of some of the guest and host protons in comparison with the chemical shifts of the same protons in the free compounds.

Properties of the Nanoscale Hydrophilic Cationic Pigment Based on Quaternary Surfactant

Dispersions of four nanoscale hydrophilic cationic pigments were prepared by micro jet milling process, in which the dodecyl trimethyl ammonium chloride (DTAC), tetradecyl trimethyl ammonium chloride (TDAC), hexadecyl trimethyl ammonium chloride (CTAC), and octadecyl trimethyl ammonium chloride (STAC) were used as the dispersers respectively. Zeta potential, particle size, viscosity and dispersion stability were tested. The effect of the hydrophobic chain of cationic quaternary surfactant on pigment dispersion's properties was discussed. The results showed that good dispersion effects were obtained when the hydrophobic chain were 14 or 16.

Thermodynamics of micelle formation of alkyltrimethylammonium chlorides from high performance electric conductivity measurements

Understanding micelle formation requires its complete thermodynamic characterization. In this work micellization of the model ionic surfactants decyltrimethylammonium chloride (DETAC), dodecyltrimethylammonium chloride (DTAC) and tetradecyltrimethylammonium chloride (TTAC) was investigated by high performance conductivity measurements, using instrumentation developed in our laboratory. The temperature dependence of the critical micelle concentration exhibits a minimum characterized by Δ mic H 0 = 0 (endothermic to exothermic process) and the degree of micelle ionization increases slightly with increasing temperature. The temperature change of Δ mic S 0 indicates that the process of micellization is entropically driven. Δ mic G 0 is always negative and slightly temperature dependent. The temperature dependence of the thermodynamic parameters is discussed in terms of the alkyl chain length and nature of the counterion. The micellization process is more favourable for surfactants with longer alkyl chain length and larger (less hydrated) counterions.

Adsorption and micelle formation of alkylammonium chloride–alkyltrimethylammonium chloride mixtures

The surface tension of the aqueous solutions of binary cationic surfactant mixtures of (1) dodecylammnonium chloride (DAC)–tetradecyltrimethylammonium chloride (TTAC), (2) decylammonium chloride (DeAC)–dodecyltrimethylammonium chloride (DTAC), and (3) DAC–DTAC was measured as a function of the total molality and composition of surfactants at 298.15 K. The compositions of surfactants in the adsorbed film and micelle were evaluated and the phase diagram of adsorption and that of micelle formation were constructed. Furthermore the excess Gibbs energies of adsorption and micelle formation were calculated to estimate the deviation from the corresponding ideal mixing. It was found that the surface and micelle are enriched in trimethylammonium salts in (1) and (2), while in ammonium salt in (3) compared to the bulk solution. On the other hand, the micelle is enriched in trimethylammonium salts compared to the surface at the critical micelle concentration (CMC) in all the systems. The miscibility of the surfactants was clarified from the standpoints of the structure of the head group and of the matching between the size of polar head group of surfactants and the difference in hydrocarbon chain length.

Effects of Alkyl Chain Length on Synergetic Adsorption and Micelle Formation in Homologous Cationic Surfactant Mixtures

The surface tensions (gamma) of the aqueous solutions of tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DTAB) were measured as a function of the total molality of surfactants (m) and the relative proportion (composition) of DTAB (X(2)) at 298.15 +/- 0.05 K under atmospheric pressure. The effect of the difference in the hydrophobic chain length between hexadecyltrimethylammonium bromide (HTAB) and DTAB on the synergism was examined. This synergism was observed in the miscibility at the surface of a mixture of these two compounds. The excess Gibbs energy of adsorption of the TTAB-DTAB system was positive in contrast to the HTAB-DTAB system. This indicates that there are certain restrictions on the difference in the hydrophobic chain length for the synergism to be brought about in homologous cationic surfactant mixtures. This mechanism was explained by the theory of a staggered structure formation at the air/water interface. A similar argument successfully applied to the hexadecyltrimethylammonium chloride (HTAC)-dodecyltrimethylammonium chloride (DTAC) and tetradecyltrimethylammonium chloride (TTAC)-DTAC mixtures also.

Orientation and Dynamics of Benzyl Alcohol and Benzyl Alkyl Ethers Dissolved in Nematic Lyotropic Liquid Crystals. 2H NMR and Molecular Dynamics Simulations

Most drugs have to cross cell membranes to reach their final target. A better understanding of the distribution, interactions, and dynamics of biologically active molecules in model bilayers is of fundamental importance in understanding drug functioning and design. 2H NMR quadrupole splittings (delta nu(Q)) and longitudinal relaxation times (T1) from the aromatic ring of benzyl alcohol-d5 (C0), a commonly used anesthetic, and a series of linear alkyl benzyl-d5 ethers with chain lengths from 1 to 12 carbon atoms (C1-C12), were measured. The molecules were dissolved in a nematic discotic lyotropic liquid crystal solution made of tetradecyltrimethylammonium chloride (TTAC)/decanol (DeOH)/NaCl/H2O. Values of delta nu(Q) and T1 from 1,1-dideuteriodecanol (15% enriched) and DHO (H2O with 0.2% D2O) were also measured. Delta nu(Q) of DeOH and DHO remained constant throughout the series. The value of delta nu(Q) of the para position of the ring (delta nu(p)) in C1 is 30% smaller than the delta nu(p) of C0. This is attributed to the existence of an H-bond between the alcohol hydroxyl proton and the solvent, which influences the average orientation of the ring. The relaxation data show that T1o,m is always longer than T1p and both decrease with the increase in alkyl chain length. Molecular dynamics simulations of the experimentally studied systems were performed. The aggregate was represented as a bilayer. The distribution, average orientation, and order parameters of the aromatic ring of the guest molecules in the bilayer were examined. Rotational correlation functions of all the C-D bonds and the OH bond from H2O were evaluated, allowing an estimate of the correlation times and T1. According to these results all spins relax in extreme narrowing conditions, except DeOH. Experimental and calculated T1 values differ at most by a factor of 3. However, the order of magnitude and the observed trends are well reproduced by the calculations. The aromatic ring of C0 possesses a unique average orientation in the bilayer. For the ether series, the orientation is modified and the C2 symmetry axis of the aromatic ring is exchanging between two orientations averaging the quadrupole splittings from the ortho and meta positions. The simulation supports the existence of an H-bond between C0 and the solvent not found in the ethers, which should be responsible for the observed differences.

Mixtures of Mucin and Oppositely Charged Surfactant Aggregates with Varying Charge Density. Phase Behavior, Association, and Dynamics

The nonionic surfactant Tween80 is a commonly used excipient in drug formulations containing an active substance with low aqueous solubility. Model drug vehicles with varying charge density were obtained by mixing Tween80 (PS-80) with the cationic surfactant Tetradecyltrimethylammonium chloride (TTAC), thus forming mixed micelles. The micelles were mixed with the negatively charged polyelectrolyte mucin, which is a component in the protective mucus layer covering epithelial cell linings. Depending on the composition of the mixture, complex-formation could be followed by precipitation. Using X-ray diffraction, it was found that the precipitate contained a lamellar phase with properties sensitive to the proportion of PS-80. Higher amounts of PS-80 were found to oppose phase separation. Further analysis in the one-phase region, or alternatively of the supernatant of two-phase samples, by (1)H NMR, HPLC, and diffusion measurements with PGSE-NMR led to the conclusions that at low proportion of PS-80 aggregates composed of mixed (PS-80 and TTAC) micelles and mucin were formed, whereas increased concentrations of PS-80 favored the dissolution of the precipitate and limited the interactions between mixed micelles and the polymer.

Micellar Counterion Binding Probed by Fluorescence Quenching of 6-methoxy-N-(3-sulfopropyl)quinolinium

The halide sensitive fluorescence probe, 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ), provides a direct approach for measurement of halide concentrations dissociated from the surfactant monomer and micelle. The gel filtration method confirms that the water-soluble SPQ probe will tend to partition in aqueous bulk phase without trapping in cationic micelles. The fluorescence of SPQ is quenched by free halide ions with a linear Stern-Volmer relation below the CMC of cationic surfactants. The Stern-Volmer plot gave a distinct break at CMC owing to the counterion binding to micelles. The CMC and degree of micellar counterion binding (β) are generally in agreement with those obtained by conductivity method. The SPQ fluorescence quenching had high sensitivities with Stern-Volmer constants of 125 M-1 (chloride) and 223 M-1 (bromide), while it was insensitive to nitrate ion. The selective quenching behavior shows that the nitrate ions bind to micelles displacing bromide for tetradecyltrimethylammonium micelles. The increase in counterion binding to micellar surface lower the CMC of surfactants, TTAOAc (tetradecyltrimethylammonium acetate) > TTAC (tetradecyltrimethylammonium chloride) > TTAB (tetradecyltrimethylammonium bromide) > TTAN (tetradecyltrimethylammonium nitrate).

Tautomerization of 2-acetylcyclohexanone in assemblies of cationic surfactants

The kinetic study of the keto-enol interconversion of 2-acetylcyclohexanone (ACHE) has been performed in organic solvents such as dimethylsulfoxide, 1-propanol, 2-propanol, methanol, dioxane, tetrahydrofuran and acetonitrile, as well as in aqueous micellar solutions of the cationic surfactants tetradecyltrimethylammonium chloride and tetradecyltrimethylammonium bromide at 25 °C. Either the solvent-assisted or H+-catalyzed reaction rates of tautomerization are reduced in both organic solvents and in micellar medium. In 70% v/v solvent–water or at fixed concentration of any cationic surfactant, the observed rate constant moderately increases with [H+]. The nitrosation of the enol has also been studied in micellar solutions of both cationic and anionic surfactants. Under experimental conditions of first-order dependence on [H+], [nitrite], and [X−] (X = Cl or Br), the presence of cationic micelles reduces strongly the rate of nitrosation, whereas in the presence of anionic micelles, the first-order rate constant, ko, goes through a maximum on increasing the surfactant concentration.

Studies on dodecyl betainate in combination with its degradation products or with phosphatidyl choline-phase behavior and hemolytic activity.

Surface active betaine esters contain a hydrolysable bond and give naturally occurring products (fatty alcohol and the amino acid betaine) on degradation. They are therefore interesting candidates for use as cationic surfactants in pharmaceutical applications. In this work the phase behavior of two systems of relevance for the utilization of dodecyl betainate as a pharmaceutical excipient is studied, namely dodecyl betainate/dodecanol/betaine hydrochloride/D2O and dodecyl betainate/phosphatidyl choline (PC)/ethanol/D2O. The techniques used for phase characterisation were 2H NMR measured on the solvent, small angle X-ray spectroscopy and optical microscopy. Dilute dodecyl betainate/PC dispersions were characterized using laser diffraction. It is shown that introduction of relatively small amounts of the hydrolysis products of dodecyl betainate, i.e., dodecanol and betaine (used in the form of betaine hydrochloride), has a strong effect on the phase behavior of the binary dodecyl betainate/D2O system. The degradation products change the average curvature of the surfactant film so that, instead of a hexagonal phase at concentrations above the micellar phase, a probably defective, lamellar phase seems to form. The dodecyl betainate/PC/ethanol/D2O system shows a large region of a highly swelling lamellar phase. Dispersions of dodecyl betainate/PC/ethanol in water can be prepared with low energy input; i.e., the preconcentrate can be regarded as a self-dispersing solution. Introduction of dodecyl betainate and its degradation products does not impair the ability of PC to form vesicles. Experiments for evaluating the toxicity of surface active betaine esters to erythrocytes were also performed. There are indications that the hemolytic activity of dodecyl betainate is lower than that of the stable surfactant tetradecyltrimethylammonium chloride, which has similar critical micelle concentration. A combination of dodecyl betainate and PC gives very low hemolytic activity.

Structure and Aggregation Number of a Lyotropic Liquid Crystal: A Fluorescence Quenching and Molecular Dynamics Study

The structure and aggregation number of a discotic lyotropic liquid crystal, prepared from tetradecyltrimethylammonium chloride (TDTMACl)/decanol (DeOH)/NaCl/H2O, have been examined using fluorescence quenching of pyrene by hexadecylpyridinium chloride and molecular dynamics (MD). The fluorescence method gives an aggregation number of 258 +/- 25 units (DeOH + TDTMACl). From the MD simulation, a lower limit for the aggregate dimension of 130 units of DeOH + TDTMACl is predicted. A stable oblate aggregate of 240 units was studied in detail. A strong polarization between the ammonium headgroups and chloride ions is observed from the calculated trajectory. DeOH headgroups are located, on average, 0.3 nm more to the interior of the aggregate than the TDTMACl headgroup and contribute to widening the interface by forming H-bonds with water. The radial distribution function of the ammonium headgroup shows that there are 16 water molecules in the first solvation sphere. The diagonal elements of the order parameter tensor of the tail atoms of both surfactants indicate that the interior of the micelle preserves about the same degree of order as at the interface, up to the last three atoms of the aliphatic chain, where the order starts to decrease.

Determination of Isotherms for Binding of Surfactants to Vesicles Using a Surfactant-Selective Electrode

Mixtures of the nonionic lipid glycerol monooleate with four cationic surfactants have been investigated. The surfactants were cetyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, and dodecyltrimethylammonium chloride, and one with a partially fluorinated chain, N-(1,1,2,2-tetrahydroperfluorodecanyl)pyridinium chloride. With a low addition of the cationic surfactant, GMO easily forms vesicles. Using a surfactant selective electrode, binding isotherms of the surfactants to a suspension of preformed vesicles were determined. The mole fractions of surfactant at which the micelle−vesicle coexistence region and the micelle region were reached, as obtained from the binding isotherms, were compared to the location of the corresponding phase borders in the phase diagrams of the respective mixtures. The different stages of the solubilization process were directly followed using cryo-TEM. Instead of a micelle−vesicle coexistence region, perforated vesicles were observed during the solubilization w...

Effect of carrier type on coupled transport kinetics of thiocyanate ions through liquid membranes

Coupled transport of thiocyanate ions through a liquid membrane containing quaternary ammonium chloride salts in chloroform was examined. The influences of the carrier type in the membrane phase on the coupled transport of thiocyanate ions were investigated. The kinetics of the coupled transport were analyzed in the formalism of two consecutive irreversible first-order reactions and the kinetic parameters ( k 1 d , k 2 m , k 2 a , R m max, t max, J d max, J a max) were also calculated. For the coupled transport of thiocyanate ions, quaternary ammonium chloride salts having different carbon atom numbers ( C n ) used as carriers were found to increase thiocyanate ions transport efficiency with increasing carbon atom numbers. Tetradecyl trimethylammonium chloride (TDTMACl), hexadecyl trimethylammonium chloride (HDTMACl), and tetraoctyl ammonium chloride (TOACl) were found to be the most effective carrier types for transport of thiocyanate ions when C n is greater than 16. The activation energies for maximum membrane entrance and exit fluxes were calculated as 32.45 kJ/mol and 34.75 kJ/mol, respectively. The values of the activation energy indicate that the process is controlled by species diffusion.

The Growth of Self-Assembled Titania-Based Films at the Air - Water Interface

The surfactant-assisted assembly of new titania-based films at the air–water interface has been monitored by time-resolved energy-dispersive reflectometry using X-rays and neutrons. Two films are described. The first, prepared from an aqueous alkaline solution containing Ti(OBun)4 and the cationic surfactant tetradecyltrimethylammonium chloride (C14TAC), shows short-range ordering. In moderately alkaline solution (pH ~ 10), triethanolamine (TEA) was required to complex the titanium alkoxide precursor to prevent immediate heterogeneous precipitation of titania. Reflectometry shows that the assembly is partly structured and comprises only a few layers. The film forms within 30 min of mixing the reagents. No further significant structural changes were detected until, after several hours, severe compression buckling prevented further reflectivity measurement. The second film, obtained from aqueous acidic solution containing Ti(OBun)4 and sodium dodecyl sulfate (SDS), contains material that is highly ordered. Strongly acidic conditions (pH < 1) enabled immediate heterogeneous precipitation of titania to be avoided prior to reaction with the dilute aqueous SDS solution. The film prepared by this route displayed a Bragg peak corresponding to a d-spacing of 35 Å. The formation of these films is reconciled in terms of the attraction between the surfactant headgroup and titania above and below the pH of the formal isoelectric point of titania.