Mixtures Of Dodecyltrimethylammonium Bromide Research Articles

Influence of n-alcohols on aqueous DTAB micelles studied by ultrasonic analysis

Abstract The influence of chain length of n-alcohols such as 1-butanol, 1-pentanol, 1-hexanol and 1-heptanol on cationic dodecyl trimethyl ammonium bromide (DTAB) micelles has been investigated. The effect of concentration was determined at alcohol concentrations of (10, 20, 30, 40 and 50) mM and at temperatures of 298.15 K, 303.15 K, 308.15 K and 313.15 K using ultrasonic velocity, density, viscosity and conductivity measurements. To study molecular interactions in micelles of various mixtures of DTAB and n-alcohols by using acoustical parameters, such as adiabatic compres-sibility (β ad), intermicellar free length (L f ), acoustic impedance (Z), molar volume (V M ) have been calculated by using ultrasonic velocity (U) and density (ρ). With the help of the trends observed when varying these parameters, the molecular interactions and thus the micellar growth of mixed systems of DTAB and n–alcohol were discussed. Viscosity data such as absolute viscosity, viscous relaxation time, oil solubilization, foam stability and conductance data complemented the observed ultrasonic data.

Interaction of crystal violet dye with dodecyltrimethylammonium bromide in aqueous and electrolyte medium at different temperatures

Dyeing is one of the most important processes in the textile industries which require optimum binding of dye with the fabrics. In the binding phenomenon of dye with the fabrics, surfactants play a significant role. The presence of different auxiliaries modifies the dye-surfactant interaction which can influence the binding of dye with the fabrics. Herein, we studied the interaction of crystal violet (CV) dye with a cationic surfactant, dodecyltrimethylammonium bromide (DTAB) conductometrically in absence and presence of electrolytes (NaBr, Na2SO4, and Na3PO4). The critical micelle concentration (cmc) of DTAB was found to dwindle with the boost of concentration of CV. The cmc of CV + DTAB mixtures were monotonically increased with the increase of temperature. The presence of electrolytes facilitates the micellization of CV + DTAB mixture. The values of counterion binding were found to be augmented with the augmentation of temperature in aqueous and NaBr media while the opposite trend was observed in Na2SO4 and Na3PO4 media. The Gibbs free energy of micellization (ΔGm0) were found to be negative in all cases. The enthalpy (ΔHm0) and entropy (ΔSm0) of micellization were negative and positive in aqueous, NaBr, and Na2SO4 media while both values were positive in Na3PO4 medium. The enthalpy–entropy compensation parameters suggest that the most stable micelle of CV + DTAB is formed in Na2SO4 medium.

Photocatalytic activity of solution combustion synthesized ZnO powders by using a mixture of DTAB and citric acid fuels

Zinc oxide (ZnO) powders were synthesized by solution combustion route using various amounts of dodecyltrimethylammonium bromide (DTAB)-citric acid mixed fuel. The structural, microstructural, optical and photocatalytic properties of ZnO powders were analyzed by modern characterization methods. Single phase ZnO powders with wurtzite structure were crystallized at all fuel contents. The ZnO powders had a foamy microstructure with the high specific surface area of 371 m2/g at higher fuel contents. The increase of band gap energy from 3.11 to 3.18 eV with the increase of fuel contents was attributed to the reduction of particle size. The adsorption capacity and photodegradation of methylene blue (MB) dye increased from 5 to 40% and 95–100%, respectively, with fuel contents.

Redox-triggered mixing and demixing of surfactants within assemblies formed in solution and at surfaces

We report experiments that test the hypothesis that redox-triggered changes in the architectures of surfactants permit control of mixing of surfactants within assemblies. Specifically, we describe surface tension, light scattering, atomic force microscopy, and quartz crystal microbalance measurements that characterize the redox-dependent behaviors of cationic surfactants with a ferrocene group located either at the surfactant terminus (11-ferrocenylundecyl-trimethylammonium bromide; FTMA) or head (N,N-dimethylferrocenylmethyldecylammonium bromide; DMFA). In bulk solution, we find that reduced and oxidized FTMA do not mix within micellar assemblies but that reduced and oxidized DMFA do form mixed micelles. Because oxidized FTMA has the architecture of a bolaform surfactant whereas oxidized DMFA has a conventional surfactant architecture with a divalent head group, these results suggest that redox-triggered changes in molecular architecture permit control of the extent of mixing of surfactants in micellar assemblies in bulk solution. This conclusion receives further support from measurements performed with mixtures of dodecyltrimethylammonium bromide and FTMA, with FTMA in either reduced or oxidized states, and was found to extend to hemimicellar assemblies formed at hydrophobic solid surfaces but not to mixed monolayers formed at the surface of water. The latter is attributed to differences in the conformations of surfactants within monolayers and micellar assemblies. Overall, these results provide insight into the design of surfactant assemblies within which mixing can be controlled reversibly using redox processes.

Micellization behavior of mixed surfactants in pure water and methanol-water mixed solvent media by density methods

The properties of anionic-rich and cationic-rich mixtures of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylsulfate (SDS) in pure water and methanol-water mixed solvent media were studied using density measurements at room temperature. The results showed that density increases with increasing concentration of surfactant mixture over the entire concentration range investigated in pure water and in the given mixed solvent media and which are found to decrease with an increase in the volume fraction of methanol in the solvent composition. The critical micelle concentration increases with the increase in volume fraction of methanol for both the anionic-rich (SDS-DTAB) and cationic-rich (DTAB-SDS) systems.BIBECHANA 13 (2016) 114-120

Effect of Hofmeister anions on the existence of the biaxial nematic phase in lyotropic mixtures of dodecyltrimethylammonium bromide/sodium salt/1-dodecanol/water

Lyotropic mixtures including different sodium salts of Hofmeister anions were studied in order to investigate the effect of these anions on the existence of biaxial nematic phase and on the uniaxial to biaxial phase transitions. For this purpose, these sodium salts were added singly into different mixtures of dodecyltrimethylammonium bromide (DDTMABr)/1-dodecanol/water, keeping the relative molar concentration of all the constituents constant. The uniaxial to biaxial phase transitions were determined from the temperature dependence of the birefringences by laser conoscopy. Micellar shape anisometry and average micellar volume were evaluated from small-angle X-ray scattering measurements. The results indicated that the Hofmeister anions were bounded to the head groups of DDTMABr molecules at the micelles’ surfaces, which significantly affect the different orientational fluctuations responsible for the formation of different nematic phases, biaxial phase domains and uniaxial to biaxial phase transition temperatures.

Effects of Ionic Strength on the Surface Tension and Nonequilibrium Interfacial Characteristics of Poly(sodium styrenesulfonate)/Dodecyltrimethylammonium Bromide Mixtures

We rationalize the surface tension behavior and nonequilibrium interfacial characteristics of high molecular weight poly(sodium styrenesulfonate)/dodecyltrimethylammonium bromide (NaPSS/DTAB) mixtures with respect to the ionic strength. Excellent agreement is achieved between experimental data and our recent empirical model [Langmuir 2013, 29, 11554], which is based on the lack of colloidal stability of bulk aggregates in the phase separation region and has no free fitting parameters. We show that the size of a surface tension peak positioned at the edge of the phase separation region can be suppressed by the addition of inert electrolyte, which lowers the critical micelle concentration in relation to the phase separation region. Such manipulation of the peak is possible for the 100 ppm NaPSS/DTAB system because there is a high free surfactant concentration in the phase separation region. The close agreement of our model with the experimental data of samples in the phase separation region with respect to the ionic strength indicates that the surface tension behavior can be rationalized in terms of comprehensive precipitation regardless of whether there is a peak or not. The time scale of precipitation for the investigated system is on the order of one month, which emphasizes the need to understand the dynamic changes in the state of bulk aggregation in order to rationalize the surface properties of strongly interacting mixtures; steady state surface properties measured in the interim period will represent samples far from equilibrium. We show also that the surface properties of samples of low ionic strength outside the equilibrium phase separation region can be extreme opposites depending on the sample history, which is attributed to the generation of trapped nonequilibrium states. This work highlights the need to validate the underlying nature of oppositely charged polyelectrolyte/surfactant systems prior to the interpretation of experimental data within an equilibrium framework.

Association Behaviors of Dodecyltrimethylammonium Bromide with Double Hydrophilic Block Co-polymer Poly(ethylene glycol)-block-Poly(glutamate sodium)

The association behaviors of single-chain surfactant dodecyltrimethylammonium bromide (DTAB) with double hydrophilic block co-polymers poly(ethylene glycol)-b-poly(sodium glutamate) (PEG(113)-PGlu(50) or PEG(113)-PGlu(100)) were investigated using isothermal titration microcalorimetry, cryogenic transmission electron microscopy, circular dichroism, ζ potential, and particle size measurements. The electrostatic interaction between DTAB and the oppositely charged carboxylate groups of PEG-PGlu induces the formation of super-amphiphiles, which further self-assemble into ordered aggregates. Dependent upon the charge ratios between DTAB and the glutamic acid residue of the co-polymer, the mixture solutions can change from transparent to opalescent without precipitation. Dependent upon the chain length of the PGlu block, the mixture of DTAB and PEG-PGlu diblocks can form two different aggregates at their corresponding electroneutral point. Spherical and rod-like aggregates are formed in the PEG(113)-PGlu(50)/DTAB mixture, while the vesicular aggregates are observed in the PEG(113)-PGlu(100)/DTAB mixture solution. Because the PEG(113)-PGlu(100)/DTAB super-amphiphile has more hydrophobic components than that of the PEG(113)-PGlu(50)/DTAB super-amphiphile, the former prefers forming the ordered aggregates with higher curvature, such as spherical and rod aggregates, but the latter prefers forming vesicular aggregates with lower curvature.

Application of the Ferguson principle to the antibacterial activity of mono- and multi-component solutions of quaternary ammonium surface-active agents.

Abstract Critical micelle concentrations (cmc) have been measured by the surface tension method for binary mixtures of dodecyltrimethyl-ammonium bromide with tetradecyltrimethylammonium bromide, binary mixtures of C14/C16 homologues, a ternary mixture of the C12/C14/C16 compounds and additionally for each component individually. The antibacterial activities of the systems against Escherichia coli were determined by a British Standard Method (B.S. 3286: 1960). Thermodynamic activities of the solutions at two survivor levels, calculated from the physical and biological measurements, were sufficiently constant to sustain the Ferguson principle for these micelle-forming antibacterial agents. A theoretical treatment of micelle formation for multi-component solutions of surfactants gave cmc’s by calculation in close agreement with the experimentally determined values. The purity and composition of the surfactants was determined by gas liquid chromatography.

Hybrid Silica-Silicone Nanocapsules Obtained in Catanionic Vesicles. Cryo-TEM Studies

An effective way to obtain hollow hybrid silica-silicone nanocapsules of controlled diameter is presented. For that purpose a new precursor of silica-silicone material, tetra(triethoxysilylethyl) tetramethylcyclotetrasiloxane, was synthesized by hydrosilylation of vinyltriethoxysilane with tetramethylcyclotetrasiloxane. Mixture of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylbenzenesulfonate (SDBS) in the cationic (the DTAB/SDBS system) rich region of the phase diagram was used to form the vesicular templates. The hybrid silica-silicone nanocapsules was obtained in base-catalyzed polymerization/polycondensation processes of the precursor inside of vesicle membrane. The shape and morphology of the silica-silicone nanocapsules was evaluated using transmission cryo-electron microscopy (cryo-TEM). Cryo-TEM reveals formation of discrete hollow shells of diameter consisted with the sizes of equilibrium vesicles used for templating.

On Plate Resolution of Three-Component Mixture of Cationic Surfactants with Mixed Aqueous-Organic Eluents Containing Formate Ion

The chromatography of three long chain aliphatic quaternary ammonium halides (cationic surfactants) was performed on kieselguhr layers using different solvent systems. The mutual separation of dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), and hexadecyltrimethylammonium chloride (HTAC) was achieved with the solvent system methanol: 10% aqueous sodium formate (30:70, v/v) on kieselguhr layer. The effect of nature of alkane chain length of alcohols on the mobility of DTAB, TTAB, and HTAC and also the effect of formate ion substituted by acetate ion and benzoate ion of sodium acetate and sodium benzoate respectively on the mobility of these surfactants were studied. The effect of the nature of different adsorbents (kieselguhr, silica gel, and alumina) on the mobility of DTAB, TTAB, and HTAC was also studied. The interference of metal cations as impurities on the resolution of mixture of DTAB, TTAB, and HTAC was also examined. The limits of detection of DTAB, TTAB, and HTAC estimated were 3.3, 3.1, and 2.8 µg/zone respectively. The developed method was utilized to separate these surfactants from different spiked water samples.

Aqueous two-phase system of an anionic gemini surfactant and a cationic conventional surfactant mixture

The aqueous two-phase system formed by the mixture of dodecyltrimethylammonium bromide (DTAB) with a gemini surfactant O,O′-bis(sodium 2-lauricate)- p-benzenediol (C 11 pPHCNa) has been studied. Two two-phase regions were observed, one was a wide region in the cationic surfactant-rich side and the other in the vicinity of R = 1:1, where R is the mixing mole ratio of DTAB to C 11 pPHCNa in global solution. Multi-lamellar vesicles are formed in the concentrated upper phase of cationic surfactant-rich systems and spherical aggregates in the concentrated bottom phase at R = 1:1. The microstructure of the solution and the phase behavior of the aqueous two-phase system strongly depended on the total concentration and the composition of the system.

Laterally nanostructured adsorbed layers of surfactant/surfmer mixtures before and after polymerisation

The adsorbed layer structure of mixed films of the polymerisable cationic surfactant dodecyldimethyl(ethylmethacrylate)ammonium bromide (MEDDAB) with the cationic and non-ionic surfactants dodecyltrimethylammonium bromide (DTAB) and polyoxyethylene-23-lauryl ether (C 12E 23) has been investigated by AFM soft-contact imaging before and after solution polymerisation of MEDDAB. MEDDAB alone adsorbs on mica as a planar bilayer, but the adsorbed layer structure can be modified by mixing with DTAB or C 12E 23 to yield an adsorbed mesh or cylinders. The equilibrium adsorbed film structure after solution polymerisation of the methacrylate group on MEDDAB was found to depend on the solubilising ability of the non-polymerisable surfactant. C 12E 23 effectively prevented precipitation of polymerised MEDDAB, retaining the unpolymerised adsorbed layer structure, whereas DTAB mixtures became cloudy above 23 mol% MEDDAB. The resultant structure remained similar to the adsorbed rods formed prior to polymerisation, but had a diameter several times larger.

Adsorption of DNA and Dodecyl Trimethylammonium Bromide Mixtures at the Air/Water Interface: A Neutron Reflectometry Study

The interactions between dodecyl trimethylammonium bromide (C12TAB) and two samples of DNA with widely differing molecular weights have been studied using surface tension and neutron reflectometry. Neutron reflection data show that the surfactant and polymer are adsorbed together in a highly cooperative fashion over a 1000-fold change in surfactant concentration. Furthermore, the shorter DNA fragments adsorb with C12TAB as trilayers at higher surfactant concentrations, with overall layer thicknesses of 65-70 A. The high molecular weight DNA, however, shows only approximate monolayer adsorption with thicknesses varying from 19 to 26 A over the entire range of C12TAB concentrations. The difference in behavior between the different samples is believed to be a result of the rigid double helical structure of DNA which makes the formation of bulk phase polymer/micelle aggregates much less favorable for the short fragments. The resulting increase in the critical aggregation concentration (CAC) then leads to the adsorption of additional surfactant/polymer complex to the underside of the initial stable surface active DNA/C12TAB complex. Comparison with previous results obtained for synthetic polyelectrolytes shows that DNA/C12TAB complexes are not capable of reducing the surface tensions to the extent that other mixtures such as the poly(styrene sulfonate)/C12TAB mixtures do. A possible reason for this is the high rigidity of DNA combined with the fact that its hydrophobic moieties are positioned within the double helix so that the external molecule is largely hydrophilic.

Structure of mixed DTAB/DDAB adsorbed layers on quartz: A neutron reflectometry and atomic force microscopy study

The structure and composition of adsorbed layers formed by mixtures of dodecyltrimethylammonium bromide (DTAB) and didodecyldimethylammonium bromide (DDAB) on quartz have been determined using a combination of atomic force microscopy and neutron reflectometry. The mixed adsorbed layer was found to be substantially enriched in DDAB, stabilising the formation of a laterally unstructured bilayer even when there is only as little as 1 mol% present in the bulk mixed solute. At even higher DTAB content the adsorbed film morphology gradually transforms to globules over a very narrow composition range. DDAB was found to be significantly excluded from the mixed adsorbed film only after it was completely transformed into globular aggregates, the equilibrium adsorbed layer morphology of DTAB.

Silicone Nanocapsules Templated Inside the Membranes of Catanionic Vesicles

A simple and effective way to synthesize hollow silicone resin particles of controlled diameter is presented. The synthesis utilizes catanionic vesicles as templates for the polycondensation/polymerization processes of 1,3,5,7-tetramethylcyclotetrasiloxane (D4H) within their membranes. Two different surfactant systems were used to form the vesicular templates: mixtures of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylbenzenesulfonate (SDBS) in the cationic (the DTAB/SDBS system) or anionic (the SDBS/DTAB system) rich region of the phase diagram. The templates obtained from these surfactant mixtures form spontaneously unilamellar vesicles in aqueous solution. The vesicular templates swell upon addition of D4H, thus increasing their size. The silicone resin was obtained in acid- or base-catalyzed polycondensation and ring-opening polymerization processes of D4H. In the case of the DTAB/SDBS system the formation of a densely cross-linked silicone material with SiO3/2 units allowed the nanocapsules to retain the vesicular shape after removal of the template, whereas in the SDBS/DTAB system, the polymer produces capsules which are too smooth to support surfactant lysis. The morphology of the silicone nanocapsules was analyzed using transmission electron microscopy (TEM) and, in some cases, atomic force microscopy (AFM). TEM and AFM reveal discrete hollow particles with a small amount of linked or aggregated hollow silica shells.

The nature of the coacervate formed in the aqueous dodecyltrimethylammonium bromide–sodium 10-undecenoate mixtures

The formation of a coacervate in mixtures of dodecyltrimethylammonium bromide (DTAB)–sodium 10-undecenoate (SUD) aqueous mixtures was studied by light scattering, ζ potential measurements, and electronic microscopy. The coacervate appears when the ζ potential goes to zero, and the energy barrier against agglomeration disappears, promoting the agglomeration of micelles. Rod-like micelles agglomerate in bundles in the DTAB-rich side of the phase diagram, while spherical or globular micelles agglomerate in clusters in the SUD-rich side. This difference explains the differences in the transition micelles–coacervate in the opposite sides of the two-phase region.

Interaction of oppositely charged polyelectrolyte-ionic surfactant mixtures: adsorption of sodium poly(acrylic acid)-dodecyl trimethyl ammonium bromide mixtures at the air-water interface.

The adsorption of the polyelectrolyte-cationic surfactant mixture of sodium poly(acrylic acid), NaPAA, and dodecyl trimethyl ammonium bromide, CTAB, at the air-water interface has been studied using neutron reflectivity and surface tension. The results provide direct evidence of the relative roles of the electrostatic and hydrophobic interactions between the polyelectrolyte and surfactant on the adsorption behaviour. At both pH 4.2 and 9.2 the addition of NaPAA results in a strong reduction in the surface tension at low CTAB concentrations, consistent with the adsorption of polymer-surfactant complexes at the interface. This is confirmed and quantified by neutron reflectivity measurements. At pH 4.2 a mixed polymer-surfactant monolayer (∼20 Å thick) is adsorbed at the interface over the entire surfactant concentration range measured. Whereas at pH 9.2, where the polyelectrolyte is more highly charged, the adsorption pattern is similar at low surfactant concentrations to that measured at low pH. However, at higher surfactant concentrations there is a transition from monolayer adsorption to the formation of a 'layered' structure at the interface. This is indicative of a stronger polymer-surfactant interaction at the surface, and has some similarity with that observed in other polyelectrolyte-ionic surfactant mixtures. At high pH, the results imply that at the lower surfactant concentrations the adsorption is dominated by the hydrophobic interaction, whereas at higher surfactant concentrations it is dominated by the electrostatic interaction. At low pH the dominant interaction would appear to be hydrophobic in nature.

On the adsorption and condensed film formation of binary mixtures of dodecyl-, tetradecyl-, hexadecyl-, and octadecyl-trimethylammonium bromides at the mercury–electrolyte interface

The adsorption and condensed film formation on mercury at the negative potential region for binary mixtures of dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), octadecyltrimethylammonium bromide (OTAB) is studied in KBr at various temperatures from 5 to 45 °C. The formation of the CTAB condensed film is hindered with the addition of DTAB and TTAB. There are interactions between unlike hydrophobic chains. The strong interactions between the CTAB molecules do not take place when DTAB or TTAB is present above a certain concentration. This hindering is more pronounced in the case of TTAB compared to the same DTAB concentration, i.e. the increase of the chain length hinders the film formation. The initially adsorbed molecules play a templating role in the kinetics of the film formation and in the self-assembling of the molecules. The initial induction time strongly depends on the temperature. The less surface active CTAB can hinder the OTAB film formation in binary mixtures. Also, increased interaction between OTAB and CTAB can be observed, indicating synergy effects in the film formation in some cases. The temperature range that the film is formed can be changed using mixtures of surfactants. Thus, the development of the film can become impossible, more difficult or even easier. Hysteresis phenomena are observed. The capacity versus time curves in the case that condensed film is formed are treated with the Avrami plot formulation, giving values between 1.5 and 2 indicating a progressive one dimensional nucleation with constant growth rate or a decrease of the nucleation rate during the overall film formation. There is generally a marked effect of the chain length of the alkyl chain on the film formation.

Effects of interactions on the formation of mixed micelles of 1,2-diheptanoyl- sn-glycero-3-phosphocholine with sodium dodecyl sulfate and dodecyltrimethylammonium bromide

Mixed micelles of the phospholipid 1,2-diheptanoyl- sn-glycero-3-phosphocholine (DHPC) with sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium bromide (DTAB) in aqueous solutions and the effects of interactions between the components were studied by fluorescence and NMR measurements. The regular solution theory (RST) was applied to analyze the experimental critical micelle concentration values determined from the fluorescence spectra of pyrene in the mixed micelles. Negative values for the interaction parameter ( β 12 ) were obtained for both DHPC + SDS and DHPC + DTAB mixtures, with the value being more negative in the former case. The negative β 12 values for the two systems imply that the interaction between the phospholipid and the two ionic surfactants is attractive in nature, being more intense in the case of DHPC + SDS. The interaction parameter, β 12 , varies with composition of the mixtures indicating changes in packing. The proton NMR shifts are quite different for the two systems and also vary with composition. An interpretation of these experimentally determined chemical shifts in terms of the degree of compactness attributed to electrostatic and steric interactions in the mixed micelle supports the conclusions derived from the fluorescence cmc experiments.