Mixed micelles of hexadecylpyridinium bromide + tetradecyltrimethylammonium bromide in aqueous glycol oligomers

Conductances of hexadecylpyridinium bromide (HPyBr) + tetradecyltrimethylammonium bromide (TTAB) mixtures over the entire mole fraction range of HPyBr (α_HPyBr) were measured in pure water as well as in the presence of various aqueous ethylene glycol oligomers containing 10 and 30 wt% of each additive in their respective binary mixtures at 30°C. Each conductivity curve shows two breaks corresponding to two critical micelle concentrations (cmc; C₁ and C₂ over the whole mole fraction range of HPyBr + TTAB mixtures except in the presence of pure HPyBr and TTAB, where a single break was observed. From the conductivity data, various micellar paramelers in the absence and presence of glycol additives were computed. A variation in the micellar parameters in the presence of additive showed that additive introduction mainly influence the medium properties and therefore the micellar properties. However, no significant micelle-glycol interactions were observed even with an increase in the number of repeating units from ethylene glycol to polyethylene glycol 600. The mixing behavior of HPyBr + TTAB is close to nonideal and is identical in pure water and in the presence of various glycols. This has been attributed to the presence of synergistic interactions between unlike monomers at C₁ that are not influenced even by the presence of additives. The appearance of the second cmc is mainly attributed to structural transitions of the mixed micelles at C₁ with a further increase in surfactant concentration.     

Polymer-Induced incompatibility in the mixed micelle formation of cationic surfactants with bulky polar head groups

The conductances of tetradecyltrimethylammonium bromide (TTAB)+tetradecyl triphenylphosphonium bromide (TTPB) mixtures over the entire mole fraction range were measured in aqueous poly(vinyl pyrrolidone) (PVP) containing 1 to 10 wt% of PVP at 30°C. Each conductivity (κ) curve showed a single break corresponding to the mixed micelle formation in the presence of PVP over the whole mole fraction range. From the conductivity data, various micellar parameters in the presence of PVP were computed and discussed in terms of micelle-polymer interactions. The mixing behavior of TTAB+TTPB in pure water was close to ideal, whereas in the presence of PVP a significant degree of nonideality was sobserved that was evaluated by computing the mole fraction of TTAB in the mixed micelle state (x ₁) and the interanction parameter (β) by using the regular solution approach. The former is less than the value in the ideal state, and the latter is much greater, indicating the enhancement in the antagonistic mixing behavior of TTAB+TTPB in the presence of PVP. The results have been explained on the basis of an increase in the incompatibility between the monomers of TTAB and TTPB in the mixed state due to the steric hindrances created by the PVP upon adsorption at the micelle-solution interface. The results have also been further supported by comparing with those of structurally similar cationic binary combinations in the presence of PVP.     

Hydrophobic hydration of cationic mixed micelles by alkoxyethanols in aqueous media

The conductances of hexadecylpyridinium chloride (HPyCl) + tetradecyltrimethylammonium bromide (TTAB) mixtures over the entire mole fraction range of HPyCl (α_HPyCl) were measured in aqueous binary mixtures of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether containing 10 to 30 wt% additive in their respective binary mixtures at 30°C. Each conductivity curve showed a single break over the whole mole fraction range of HPyCl + TTAB mixtures. From the break in the conductivity curve, various micellar parameters were calculated and the results were discussed on the basis of alkoxyethanol's hydrophobic hydration of the mixed micelle. The micellar parameters of HPyCl, TTAB, and of their mixtures showed a strong dependence both on the amount and on the number of repeating units of ethylene and diethylene glycol derivatives. The hydrophobic hydration was considerably higher in the case of diethylene glycol derivatives owing to the presence of an extra ether oxygen. An evaluation of the non-ideality in the HPyCl + TTAB mixtures in the presence of additives revealed that alkoxyethanols reduce the unlike surfactant monomer interactions in order to form the mixed micelles in comparison to those in pure water. It has also been observed that such interactions systematically decrease with an increase in the number of repeating units from monomethyl ether to monobutyl ether, both in the case of ethylene and diethylene glycol derivatives.     

Interaction of tetradecyltrimethylammonium bromide with bovine serum albumin in different compositions: Effect of temperatures and electrolytes/urea

Herein, the interaction of a protein, bovine serum albumin (BSA), with tetradecyltrimethylammonium bromide (TTAB, a cationic surfactant), has been investigated using the conductivity measurement technique in pure water and some sodium salts (NaCl, Na₂SO₄, Na₂CO₃, and Na₃PO₄) solutions at temperature range of 295.15-320.15 K. Results reveal that, in the plot of specific conductivity versus the concentration of TTAB, only a single critical micelle concentration (cmc) was found for the TTAB + BSA mixed system in all solvents media studied. The addition of BSA in aqueous TTAB solution, the value of cmc undergoes a change from its pure form, which indicates the presence of strong interaction operating between the BSA and TTAB molecules. In aqueous system, the cmc values of the TTAB + BSA mixtures are obtained higher compared to the values found for single TTAB surfactant. However, the addition of salt decreases the cmc value of mixed TTAB + BSA system. The values of cmc of the BSA + TTAB mixed system at 310.15 K and 1.00 mmol·kg^-1 ionic strength of salt followed the order: cmc_Na2CO3 > cmc_Na3PO4 > cmc_NaCl > cmc_Na2SO4. The cmc values of TTAB + BSA mixture were found to be lowered in urea solution within the concentrations studied. The values of degree of dissociation (α) and fraction of counter ion binding (β) were found to be dependent on additives and temperature. The free energy of micellization (△G_m^o) is negative for all the systems, which manifests that the micellization phenomenon is energetically spontaneous. The enhancement of the negative value of △G_m^o in aqueous salt solutions reveals an increase of spontaneity of the TTAB + BSA micellization process. The values of △G_m^o also reveal that the spontaneity of micelle formation is enhanced at higher temperatures in all media studied. The values of free energy of transfer (△G_{m, t}^o) were also determined for numerous solvent media used in the present study and described with appropriate reasoning.     

Aggregated assemblies of hexadecyltrimethylammonium bromide and phospholipids at the interface and in the bulk solution

Interactions between hexadecyltrimethylammonium bromide (HTAB) and l-α-phosphatidylcholine (PC), 1,2-didecanoyl-sn-glycero-3-phosphocholine (DPC), and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (PPC) at the air/water interface and in the bulk solution were evaluated using interfacial tension, fluorescence, and conductivity measurements to study the aggregation processes of HTAB in fixed concentrations of aqueous lipid solutions containing 7–36 μM of each lipid. The interfacial and fluorescence measurements showed the occurrence of two kinds of aggregation processes in HTAB-PC and HTAB-DPC systems, which were identified by the three breaks at low lipid concentrations, i.e., 7–14μM. The first aggregation process, C ₁, involved the incorporation of HTAB monomers into the lipid vesicles and the subsequent disruption of the vesicular structure leading to the formation of mixed micelles. The second aggregation process, C ₂, which started at the second break, indicated the completion of the mixed micelles and the initiation of independent micelle formation process which was completed at the third break. At higher PC or DPC concentration, i.e., 14–22 μM, the first break, which indicated the initiation of the first aggregation process, was not observed; only the second and third breaks were visible. This is ascribed to the presence of comparatively large vesicles, which were able to accommodate HTAB monomers initially without any drastic change in their architecture. In the presence of PPC, the aggregation process of HTAB was similar to that in pure water as studied from the interfacial tension measurements, whereas the bulk behavior indicated the presence of strong structure transitions upon incorporation of HTAB monomers in the PPC vesicles. A difference between the aggregation behaviors of HTAB with PPC was explained on the basis of the stronger hydrophobicity of PPC over PC and DPC.     

An important factor affecting synergism on coprocessing of Taiheiyo coal with Athabasca oil sand bitumen

A series of mixtures of Japanese subbituminous Taiheiyo coal and Athabasca oil sand bitumen (AOB) with various coal concentrations (0–100 wt%) was coprocessed in a 70 ml autoclave at 420°C for 1 h in the presence of H₂ (50 kg/cm² at room temperature) and sulfided Ni---Mo/Al₂O₂ catalyst. The mixture containing 2 wt% coal produced the largest amount of hexane soluble fraction (HS) and the smallest amount of benzene insoluble fraction (BI). Thus, a synergistic liquid production occurred for this mixture with 2 wt% coal by suppressing the retrogressive reactions which proceeded for pure AOB. The HS obtained from mixtures with 2–30 wt% showed higher H/C ratios and lower heteroatom contents than those obtained from pure AOB and the mixtures with more than 30 wt% coal. The amounts of transferable hydrogen contained in the mixtures were estimated using anthracene as a hydrogen acceptor. The mixtures with 2–10 wt% coal contained higher amounts of donor hydrogen than pure AOB. The HS yield from the various mixtures was correlated with the amount of donor hydrogens contained in the mixtures, except for the mixture with 10 wt% coal. Thus, the important factor which results in synergism is suggested to be the amount of donor hydrogens contained in the feed mixtures.     

Mixed Micellar and Interfacial Interactions of a Triblock Polymer (EO37PO56EO37) with a Series of Monomeric and Dimeric Surfactants

The mixed micellar and interfacial properties of mixtures of triblock polymer (TBP) with a series of monomeric (dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and cetyltrimethylammonium bromide, and dimeric (dimethylene bis[alkyldimethylammonium bromide], m-2-m, where m = 10, 12, and 14) cationic surfactants were investigated using surface tension and viscosity measurements in aqueous solutions at different temperatures. Various physicochemical properties such as critical micelle concentration, mixed micellar mole fraction, interaction parameter, interfacial, and thermodynamic parameters were evaluated. All the binary mixtures exhibit synergistic interactions which increase with temperature and pass through a minimum with the increase in hydrophobic chain length of the cationic surfactants. The contribution of TBP in mixed micelle formation also increases with the hydrophobic chain length of the surfactants. The interfacial and thermodynamic parameters reveal that the adsorption of the surfactant mixtures at the air–solution interface is more favorable than that of micelle formation and the unfavorable enthalpy changes are overwhelmed by favorable entropy changes. Further, the mixtures of TBP with smaller chain length surfactants show a sharp rise in relative viscosity at higher mole fractions of these surfactants.     

INTERACTIONS BETWEEN POLYVINYLPYRROLIDONE AND CATIONIC GEMINI/CONVENTIONAL SURFACTANTS

The interactions of two gemini surfactants (16-s-16, s = 5, 6) and their conventional counterpart cetyltrimethylammonium bromide (CTAB) with polyvinylpyrrolidones (PVP K15 and PVP K90) were investigated using conductivity, steady-state fluorescence, and viscosity techniques. The results indicate that there is no PVP/CTAB complex formation if molecular weight of PVP < 15,000. Both PVP K15 and PVP K90 interact with gemini surfactants. The critical aggregation concentration (cac) and critical micelle concentration (cmc) increase with polymer concentration and do not depend on the polymer molecular weight. Fluorescence study shows that the addition of PVP results in a decrease of the aggregation number in all the systems investigated due to the adsorption of the PVP chain in the micelle palisade layer and the ensuing increase of micelle ionization. The viscosity results suggest that the interactions between the surfactants and the polymer affect both inter-polymer-polymer association and chain expansion.

[Supplementary materials are available for this article. Go to the publisher's online edition of Chemical Engineering Communications for the following free supplemental resources: additional data tables and figures.]     

The Effect of Ethanol on Nanostructures of Mixed Cationic and Anionic Surfactants

Micellization of tetradecyl trimethyl ammonium bromide (TTAB) and sodium dodecyl sulfate (SDS) in water–ethanol (ET) micellar solutions, with the weight percent of ET changing within the range 0–30, was studied by means of surface tension and conductivity measurements. Surface tension measurements also provided information about the dependence of the surface excess concentration, the minimum area per surfactant molecule, and the standard Gibbs energy of adsorption on the added weight percent of the organic solvent. Information about the degree of counterion dissociation and phase transition was obtained through conductivity measurements. Cyclic voltammetry (CV) and dynamic light scattering (DLS) was also employed to investigate the mixed micellar behavior of the binary mixtures. It was shown that an excess of cationic surfactant and ET resulted in a phase transition of vesicles and large micelles to mixed micelles. The regular solution theory approximation was used to determine various micellar parameters of ideal systems. The regular solution interaction parameter (β) suggests that the formation of mixed micelles is due to the synergistic interactions in the case of TTAB/SDS systems and becomes affected by the water/ET ratio.     

Some Surface Properties of Polysorbates and Cetyl Trimethyl Ammonium Bromine Mixed Systems

Mixed surfactant solutions consisting of cationic/nonionic surfactants were prepared in different compositions of the components in aqueous solution in order to determine the surface properties. The critical micelle concentration (CMC) of aqueous solutions of the individual surfactants cetyl trimethyl ammonium bromide (CTAB) and polysorbate nonionics, and their mixtures are determined at different proportions. The results show that there is synergistic behavior in mixtures at higher mole fraction of nonionic surfactant. The effect of the alkyl chain on the CMC is also determined.     

1-氨丙基-3-甲基咪唑溴盐水溶液的汽液相平衡

1-氨丙基-3-甲基咪唑溴盐([APMIm][Br])是一种对CO₂有良好吸收性能的功能型离子液体,在工业中可采用水溶液来实现高效能的吸收和解吸循环过程,因此对其水溶液特性的研究至关重要。对[APMIm][Br]水溶液在中低温度下的汽液相平衡进行了测量,获得可靠的实验数据,从而揭示其水溶液特性。实验温度范围为278.15～348.15 K,[APMIm][Br]在水溶液中质量分数分别为10.0%、20.3%、29.5%、40.0%、57.5%、75.3%、84.0%、88.9%、90.9%。考虑了低温下离子液体分子在水溶液中的强缔合特性,采用带缔合惰化因子的离子液体水溶液活度模型对实验数据进行了拟合,实验值与计算结果符合很好,平均相对误差为2.15%。     

A didodecyldimethylammonium bromide ternary system: Characterization of three-phase stable emulsions by optical microscopy

A preliminary characterization of the didodecyldimethyl ammonium bromide (DDAB)/water (W)/per fluorooctane (PFO) ternary system at 25°C is presented. The gradual addition of water, followed by mixing, to DDAB/PFO mixtures produces very stable emulsions for water contents greater than 20 wt%. On the basis of macroscopic observation, at least four different types of emulsions form up to a water content of around 97 wt%. On the basis of high conductivity values, a water-continuous domain is suggested at all compositions. A second phase diagram, considerably different in phase boundaries, is obtained by adding the PFO oil to DDAB/W samples. This allowed us to ascertain the swelling properties of Lα₁ and Lα₂ lamellar phases. Optical microscopy in the presence and in the absence of polarized light revealed the formation of lamellar liquid crystals either as randomly localized islands or as rings surrounding the oil droplets. Vesicles are identified at high water content. The contemporaneous presence of both Lα₁ and Lα₂ lamellar phases causes a synergistic effect in the PFO stabilization.     

Memory effect on semi-clathrate hydrate formation: A case study of tetragonal tetra-n-butyl ammonium bromide hydrate

Recrystallization in a tetragonal tetra-n-butyl ammonium bromide (hereafter, TBAB) semi-clathrate hydrate system has been investigated in TBAB aqueous solutions of two different concentrations (stoichiometric mole fraction for tetragonal TBAB hydrate formation and lower mole fraction than stoichiometric one) by use of optical microscopy. The recrystallization of TBAB hydrate has been observed under milder condition than that of the initial crystallization in both concentrations. In particular, solution of the lower concentration is easily recrystallized. This is the first observation of memory effect in a semi-clathrate hydrate system. In addition, the recrystallization occurs in the vicinity of the place where the last piece of initial crystal was dissociated. This implies that a small amount of residual structures remain in the dissociated water, but unfortunately they cannot be confirmed with Raman micro-spectroscopy.     

Properties of aqueous solutions for two binary mixed systems between two kinds of bile salts and nonionic surfactants

The micellar properties of aqueous binary mixed solutions for two systems consisting of sodium cholate (NaC)-octaoxyethylene glycol mono n-decyl ether (C₁₀E₈) and sodium glycocholate (NaGC)-C₁₀E₈ have been studied on the basis of surface tensions, polarity of the micelle interior and the mean aggregation number. Application of two theoretical treatments, based on regular solution and excess thermodynamic quantities for critical micellar concentration (CMC) data from surface tension curves of two mixed systems showed that the mole fraction of each bile salt in the mixed micelles near the CMC is lower than that of the corresponding prepared mole fraction in the mixed solution. The polarity of the interior suggested that the hydrophobicity of intramicelles increased with the increase of the mole fraction of bile salt in the mixed solution and that the mixed micelles become dramatically more hydrophobic at a mole fraction of 0.68 for NaGC−C₁₀E₈ system and 0.75 for NaC−C₁₀E₈ system, respectively. This implies that the micelles become richer in the bile salt molecules and the tendency appears strongly for NaGC−C₁₀E₈ system due to the strong cohesion between the conjugated glycines in the NaGC molecules. The decrease of aggregation number with the increase of the mole fraction of bile salts shows that the micelles approach those of the single system of each bile salt. This supports the previously mentioned facts.     

The influence of PVP on the synthesis and electromagnetic properties of PANI/PVP/CIP composites

Polyaniline/carbonyl iron powder (PANI/CIP) composites with core‐shell structure were synthesized via in situ polymerization in aqueous solution of polyvinylpyrrolidon (PVP). The micromorphology, structure, and microwave absorbing property of the PANI/PVP/CIP composites were characterized by scanning electron microscopy, fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and vector network analysis. And, the modified mechanism of PVP on polymerization was discussed. The research showed that the presence of PVP was conducive to not only dispersion of CIP but also the formation coated well with PANI. PANI/CIP composites that were decorated by PVP have obviously improved on wave absorbing property compared with the composites which were synthesized without PVP. With the concentrations of 10 wt% PVP, the PANI/PVP/CIP composites show best microwave absorption, which the minimum reflection loss (RL) was −26.4 dB at 38.1 GHz and the corresponding thickness was 0.9 mm; for a thickness of 1.1 mm, an RL exceeding −10 dB was obtained in the frequency range of 27.6–39.0 GHz. POLYM. COMPOS., 36:1799–1806, 2015. © 2014 Society of Plastics Engineers     

Adsorption behavior of surfactant-polyacrylamide mixtures with kaolin

The adsorption behavior of three surfactants—hexadecylpyridinium bromide (HPyBr), sodium dodecylbenzene sulfonate (SDBS), and Triton X-100 (TX-100)—on kaolin from aqueous solution is monitored as a function of pH. The nature and shape of the adsorption isotherms are typical and highly dependent on the surfactant structure. All three surfactants adsorb on kaolin beyond the limits of monolayer coverage. Isotherms for HPyBr fit the Langmuir equation well. SDBS isotherms are typical of a two-stage process, and TX-100 adsorption isotherms are S-shaped. The pH-sensitive adsorption of each surfactant and the models used to represent the isotherms are considered together in explaining the mechanism of adsorption in each case. The complex mixture adsorption behavior from polyacrylamide-surfactant mixtures is also determined in acidic and basic pH media. Three polyacrylamides, catam1, anam1 and nonam1, are chosen to represent cationic, anionic, and nonionic polymers, respectively. Both competitive and synergistic effects are noted in the mixture adsorption depending upon the polymer-surfactant pair and the mode of introduction of a second component in the presence of another. The results are explained by considering various factors such as changes in the nature of solvent power of the media, interaction between the polymer and surfactant in the bulk solution as well as at the kaolin surface, blocking of surface sites by a preadsorbed component, and the change in the conformation state of polymer chains     

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

Abstract

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.     

Interaction of Azo Dye with Cationic Surfactant Under Different pH Conditions

The aggregation induced by Alizarin Yellow R (AYR) in the cationic surfactant, cetyltrimethylammonium bromide (CTAB), was investigated by measuring their UV–visible absorption spectra. Conductance measurements as a function of surfactant concentration below and above the critical micelle concentration (CMC) were studied. CTAB aggregation takes place at the concentration far below its normal CMC in the presence of AYR. Both hydrophobic and electrostatic interactions affect the aggregation process in aqueous solution. The dye effect on the CMC of CTAB was noted by a specific conductivity method as well. AYR–CTAB binding constant (K_s) and water–micelle partition co-efficient (K_x) were quantified with the help of mathematical models employed to determine the partitioning of organic additives in the micellar phase. The number of dye molecules per micelle was estimated at particular CTAB concentrations above CMC, during this study.     

Effect of tartrazine dye on micellisation of cationic surfactants: conductometric,spectrophotometric, and tensiometric studies

The interactions between anionic dye (tartrazine) and cationic surfactants (dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide) have been studied by conductometric, spectrophotometric, and tensiometric techniques. The conductance and surface tension of dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide in pure water as well as in aqueous tartrazine when plotted with surfactant concentration gave values of the critical micelle concentration at different temperatures. As well as increasing the length of the carbon chain of surfactants, the presence of tartrazine reduces the critical micelle concentration. From specific conductivity data, the counterion dissociation constant, standard free energy, enthalpy, entropy of micellisation, surface excess concentration, surface tension at critical micelle concentration, minimum area per molecule, surface pressure at critical micelle concentration, and Gibbs energy of adsorption were evaluated. Spectroscopic studies reveal that the binding of dye to micelles brings a bathochromic shift in dye absorption spectra that indicates dye–surfactant interaction.     

Influence of sodium bromide on the thermal decomposition of tetraphenylphosphonium montmorillonite

Tetraphenylphosphonium montmorillonite (TPP-MMT) was prepared from an aqueous solution of tetraphenylphosphonium bromide and a bentonite consisting primarily of sodium rich montmorillonite (Na-MMT) together with minor amounts of cristobalite, quartz and nontronite. The original bentonite, the TPP-MMT and mixtures of TPP-MMT with various amounts of NaBr were investigated by in-situ high-temperature X-ray diffraction and thermogravimetric analysis. The decomposition of TPP-MMT was strongly dependent on the presence of NaBr. NaBr took part in a retro-reaction to Na-MMT + TPP-Br, of which the latter decomposed into gaseous products. The decomposition temperature of pure TPP-MMT was about 100 °C higher than mixtures of TPP-MMT with NaBr. The TPP-ions in pure TPP-MMT decomposed continuously within the MMT interlayer space, so that there was probably nothing left but H⁺. Since NaBr is a by-product of the TPP-MMT synthesis from Na-MMT and since halogen ions strongly influence fire retardant properties of polymer-based composites, this reaction is a critical aspect in the evaluation of such materials. Cristobalite and quartz were inert during the reactions observed up to temperatures of 1000 °C.