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Weiguo Shen - One of the best experts on this subject based on the ideXlab platform.
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volumetric studies on aqueous solutions of Dodecyltrimethylammonium Bromide and 1 dodecyl 3 methylimidazolium Bromide
Journal of Solution Chemistry, 2017Co-Authors: Peizhu Zheng, Weiguo Shen, Changfei DuAbstract: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.
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thermodynamic properties of mixed surfactants of Dodecyltrimethylammonium Bromide and 1 dodecyl 3 methylimidazolium Bromide
The Journal of Chemical Thermodynamics, 2017Co-Authors: Peizhu Zheng, Weiguo Shen, Jihua ZhaoAbstract:Abstract The mixed surfactants of Dodecyltrimethylammonium Bromide (DTAB) and 1-dodecyl-3-methylimidazolium Bromide (C 12 mimBr) in aqueous solutions were studied by measurement of electrical conductivity and isothermal titration microcalorimetry (ITC). The critical micelle concentrations (cmc) and the degree of dissociations of counter ions were determined for this system at various surfactant compositions, and the thermodynamic properties of micellization were evaluated. A one-parameter Margules equation was used to fit the cmc values to calculate the mole fraction, the activity coefficients of two surfactant components and the excess properties in mixed micelles.
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measurement of the interaction enthalpy for mixed micelles of Dodecyltrimethylammonium Bromide and 1 dodecyl 3 methylimidazolium Bromide
Journal of Industrial and Engineering Chemistry, 2016Co-Authors: Peizhu Zheng, Weiguo Shen, Jihua ZhaoAbstract:In order to clarify the nature of the inter-micellar interactions, we developed an approach to obtain the intermicellar interaction enthalpy through measuring the mixing heats of Dodecyltrimethylammonium Bromide (DTAB)/1-dodecyl-3-methylimidazolium Bromide (C12mimBr) mixed micelles by using flow-mixing calorimetry. It was found that the inter-micellar interaction enthalpies for this system were negative, representing the attractive enthalpy interactions between the mixed micelle droplets. These results are contradictory to those reported in the literature and interpreted by the predominant attractive dehydration effect of counterion. Static light scattering experiment revealed that the repulsive nature of the interaction characterized by the Gibss free energy should be dominated by the entropy interaction.
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thermodynamic study of mixed surfactants of polyoxyethylene tert octyl phenyl ether and Dodecyltrimethylammonium Bromide
Journal of Chemical & Engineering Data, 2016Co-Authors: Peizhu Zheng, Xianshuo Zhang, Jian Fang, Weiguo ShenAbstract:Mixtures of polyoxyethylene tert-octyl phenyl ether (TX100) and Dodecyltrimethylammonium Bromide (DTAB) were investigated using isothermal titration calorimetry. On the base of the pseudophase separation model and using the two-parameter Margules equation, the compositions of mixed micelles and activity coefficient of each surfactant in mixed micelles were obtained and further used to calculate the thermodynamic parameters of micellization and excess properties of mixed surfactants in the micelles. Through three titration methods, the tendency of surfactants to form mixed micelles and the interactions between TX100 and DTAB in the micelles were investigated.
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interactions between sodium polyacrylate and mixed surfactants of polyoxyethylene tert octyl phenyl ether and Dodecyltrimethylammonium Bromide
RSC Advances, 2015Co-Authors: Peizhu Zheng, Xianshuo Zhang, Weiguo ShenAbstract:The interactions between sodium polyacrylate (PANa) and mixed surfactants of polyoxyethylene tert-octyl phenyl ether (TX100) and Dodecyltrimethylammonium Bromide (DTAB) in 40 mM NaBr aqueous solutions were studied using isothermal titration calorimetry (ITC). It was found that whether DTAB was titrated into PANa/TX100 or TX100/DTAB was titrated into PANa, three endothermic peaks were detected; representing three processes: (1) binding of DTAB monomers to PANa chains through electrostatic interactions, (2) polymer-induced micellization, and (3) cross-linking of polymer chains. The interaction mechanism was interpreted using a thermodynamic model, and it was found that when the molar ratio of bound DTAB to the carboxylate group of the polymer (CpolyDTAB/Cpoly) reached about 0.5, the polymer-induced micellization occurred; while when CpolyDTAB/Cpoly reached about 1, indicating complete neutralization of the electrostatic charges on the polymer chains, the cross-linking of the polymer chains started and precipitation was observed; finally, as CpolyDTAB/Cpoly reached 1.3, the precipitate was redissolved slowly due to reversion of the charge ratio of the polymer chains.
Peizhu Zheng - One of the best experts on this subject based on the ideXlab platform.
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volumetric studies on aqueous solutions of Dodecyltrimethylammonium Bromide and 1 dodecyl 3 methylimidazolium Bromide
Journal of Solution Chemistry, 2017Co-Authors: Peizhu Zheng, Weiguo Shen, Changfei DuAbstract: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.
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thermodynamic properties of mixed surfactants of Dodecyltrimethylammonium Bromide and 1 dodecyl 3 methylimidazolium Bromide
The Journal of Chemical Thermodynamics, 2017Co-Authors: Peizhu Zheng, Weiguo Shen, Jihua ZhaoAbstract:Abstract The mixed surfactants of Dodecyltrimethylammonium Bromide (DTAB) and 1-dodecyl-3-methylimidazolium Bromide (C 12 mimBr) in aqueous solutions were studied by measurement of electrical conductivity and isothermal titration microcalorimetry (ITC). The critical micelle concentrations (cmc) and the degree of dissociations of counter ions were determined for this system at various surfactant compositions, and the thermodynamic properties of micellization were evaluated. A one-parameter Margules equation was used to fit the cmc values to calculate the mole fraction, the activity coefficients of two surfactant components and the excess properties in mixed micelles.
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measurement of the interaction enthalpy for mixed micelles of Dodecyltrimethylammonium Bromide and 1 dodecyl 3 methylimidazolium Bromide
Journal of Industrial and Engineering Chemistry, 2016Co-Authors: Peizhu Zheng, Weiguo Shen, Jihua ZhaoAbstract:In order to clarify the nature of the inter-micellar interactions, we developed an approach to obtain the intermicellar interaction enthalpy through measuring the mixing heats of Dodecyltrimethylammonium Bromide (DTAB)/1-dodecyl-3-methylimidazolium Bromide (C12mimBr) mixed micelles by using flow-mixing calorimetry. It was found that the inter-micellar interaction enthalpies for this system were negative, representing the attractive enthalpy interactions between the mixed micelle droplets. These results are contradictory to those reported in the literature and interpreted by the predominant attractive dehydration effect of counterion. Static light scattering experiment revealed that the repulsive nature of the interaction characterized by the Gibss free energy should be dominated by the entropy interaction.
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thermodynamic study of mixed surfactants of polyoxyethylene tert octyl phenyl ether and Dodecyltrimethylammonium Bromide
Journal of Chemical & Engineering Data, 2016Co-Authors: Peizhu Zheng, Xianshuo Zhang, Jian Fang, Weiguo ShenAbstract:Mixtures of polyoxyethylene tert-octyl phenyl ether (TX100) and Dodecyltrimethylammonium Bromide (DTAB) were investigated using isothermal titration calorimetry. On the base of the pseudophase separation model and using the two-parameter Margules equation, the compositions of mixed micelles and activity coefficient of each surfactant in mixed micelles were obtained and further used to calculate the thermodynamic parameters of micellization and excess properties of mixed surfactants in the micelles. Through three titration methods, the tendency of surfactants to form mixed micelles and the interactions between TX100 and DTAB in the micelles were investigated.
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interactions between sodium polyacrylate and mixed surfactants of polyoxyethylene tert octyl phenyl ether and Dodecyltrimethylammonium Bromide
RSC Advances, 2015Co-Authors: Peizhu Zheng, Xianshuo Zhang, Weiguo ShenAbstract:The interactions between sodium polyacrylate (PANa) and mixed surfactants of polyoxyethylene tert-octyl phenyl ether (TX100) and Dodecyltrimethylammonium Bromide (DTAB) in 40 mM NaBr aqueous solutions were studied using isothermal titration calorimetry (ITC). It was found that whether DTAB was titrated into PANa/TX100 or TX100/DTAB was titrated into PANa, three endothermic peaks were detected; representing three processes: (1) binding of DTAB monomers to PANa chains through electrostatic interactions, (2) polymer-induced micellization, and (3) cross-linking of polymer chains. The interaction mechanism was interpreted using a thermodynamic model, and it was found that when the molar ratio of bound DTAB to the carboxylate group of the polymer (CpolyDTAB/Cpoly) reached about 0.5, the polymer-induced micellization occurred; while when CpolyDTAB/Cpoly reached about 1, indicating complete neutralization of the electrostatic charges on the polymer chains, the cross-linking of the polymer chains started and precipitation was observed; finally, as CpolyDTAB/Cpoly reached 1.3, the precipitate was redissolved slowly due to reversion of the charge ratio of the polymer chains.
Pablo C. Schulz - One of the best experts on this subject based on the ideXlab platform.
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the aqueous catanionic system sodium perfluorooctanoate Dodecyltrimethylammonium Bromide at low concentration
Journal of Colloid and Interface Science, 2007Co-Authors: Jose L Lopezfontan, Pablo C. Schulz, Juan M. Ruso, Gerardo Prieto, Elena Blanco, Félix SarmientoAbstract:Abstract The interaction between sodium perfluorooctanoate (SPFO) and Dodecyltrimethylammonium Bromide (DTAB) was studied by several methods and it was found strongly synergistic. Above a mole fraction of SPFO in the surfactant mixture ( α SPFO ) = 0.38 , the interaction is repulsive and increases with the content of SPFO in both, the overall mixture and micelles, whereas the interaction is attractive if DTAB is in excess. At α SPFO = 0.38 the low miscibility between hydrocarbon and fluorocarbon is counterbalanced by the electrostatic attraction between the opposite charged head groups, and the micelle composition is ideal (i.e., the mole fraction of SPFO in micelles X SPFO = α SPFO = 0.38 ). The solubility of fluorocarbon in hydrocarbon is lower than that of hydrocarbon in fluorocarbon. Micelles of DTAB act as a solvent for SPFO without important structural changes, whilst micelles of SPFO undergo important changes when dissolve DTAB. This asymmetry may be interpreted as caused by the difference in chain length that favors the inclusion of the shorter chain in micelles of the longer surfactant, but disfavors the opposite process. Above X SPFO = 0.5 there is an excess adsorption of Bromide ions on the mixed micelles surface, giving rise to a high ζ potential. Micelles of pure SPFO or pure DTAB show an important energy barrier which prevents micelle flocculation. The inclusion of SPFO in DTAB micelles produces a reduction of the energy barrier, which disappeared when α SPFO = 0.5 . This produces the flocculation of micelles giving rise to the formation of a non-birefringent coacervate, which is probably formed by unordered isometric clusters of micelles.
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The aqueous catanionic system sodium perfluorooctanoate–Dodecyltrimethylammonium Bromide at low concentration
Journal of Colloid and Interface Science, 2007Co-Authors: José L. López-fontán, Pablo C. Schulz, Juan M. Ruso, Gerardo Prieto, Elena Blanco, Félix SarmientoAbstract:Abstract The interaction between sodium perfluorooctanoate (SPFO) and Dodecyltrimethylammonium Bromide (DTAB) was studied by several methods and it was found strongly synergistic. Above a mole fraction of SPFO in the surfactant mixture ( α SPFO ) = 0.38 , the interaction is repulsive and increases with the content of SPFO in both, the overall mixture and micelles, whereas the interaction is attractive if DTAB is in excess. At α SPFO = 0.38 the low miscibility between hydrocarbon and fluorocarbon is counterbalanced by the electrostatic attraction between the opposite charged head groups, and the micelle composition is ideal (i.e., the mole fraction of SPFO in micelles X SPFO = α SPFO = 0.38 ). The solubility of fluorocarbon in hydrocarbon is lower than that of hydrocarbon in fluorocarbon. Micelles of DTAB act as a solvent for SPFO without important structural changes, whilst micelles of SPFO undergo important changes when dissolve DTAB. This asymmetry may be interpreted as caused by the difference in chain length that favors the inclusion of the shorter chain in micelles of the longer surfactant, but disfavors the opposite process. Above X SPFO = 0.5 there is an excess adsorption of Bromide ions on the mixed micelles surface, giving rise to a high ζ potential. Micelles of pure SPFO or pure DTAB show an important energy barrier which prevents micelle flocculation. The inclusion of SPFO in DTAB micelles produces a reduction of the energy barrier, which disappeared when α SPFO = 0.5 . This produces the flocculation of micelles giving rise to the formation of a non-birefringent coacervate, which is probably formed by unordered isometric clusters of micelles.
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computational study of the structure and behavior of aqueous mixed system sodium unsaturated carboxylate Dodecyltrimethylammonium Bromide
Journal of Physical Chemistry B, 2006Co-Authors: Maria Lujan Ferreira, María Belén Sierra, Marcela A. Morini, Pablo C. SchulzAbstract:The mixed surfactant system sodium 10-undecenoate (SUD)−Dodecyltrimethylammonium Bromide (DTAB) was studied by computational simulation to determine the composition and structure of the mixed microstructures. Results were contrasted with experimental data obtained from literature and our own laboratory. The modelization predicts spherical or cylindrical micelles with a preferential composition of SUD-DTAB of about 1:2, while the system predicts a lamellar structure with a proportion of 1:1 when SUD is replaced by the saturated soap sodium undecanoate. The model also predicts the deep inclusion of Bromide ions in the micelle Stern layer. All predictions were in agreement with previous experimental results.
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aggregation in Dodecyltrimethylammonium Bromide didodecyldimethylammonium Bromide aqueous mixtures
Anales De La Asociacion Quimica Argentina, 2006Co-Authors: Pablo C. Schulz, Bahia BlancaAbstract:The characteristics of the aggregation of the aqueous mixed system Dodecyltrimethylammonium Bromide - didodecyldimethylammonium Bromide were studied by several techniques. The mixed systems show a coexistence of small spherical micelles, and a polydisperse mixture of vesicles and aggregates of micelles. The charge and size of aggregates were studied as a function of the mixture composition.
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The nature of the coacervate formed in the aqueous Dodecyltrimethylammonium Bromide–sodium 10-undecenoate mixtures
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006Co-Authors: María Belén Sierra, Marcela A. Morini, Pablo C. Schulz, Paula V. Messina, Juan M. Ruso, Gerardo Prieto, Félix SarmientoAbstract:Abstract 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.
Félix Sarmiento - One of the best experts on this subject based on the ideXlab platform.
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the aqueous catanionic system sodium perfluorooctanoate Dodecyltrimethylammonium Bromide at low concentration
Journal of Colloid and Interface Science, 2007Co-Authors: Jose L Lopezfontan, Pablo C. Schulz, Juan M. Ruso, Gerardo Prieto, Elena Blanco, Félix SarmientoAbstract:Abstract The interaction between sodium perfluorooctanoate (SPFO) and Dodecyltrimethylammonium Bromide (DTAB) was studied by several methods and it was found strongly synergistic. Above a mole fraction of SPFO in the surfactant mixture ( α SPFO ) = 0.38 , the interaction is repulsive and increases with the content of SPFO in both, the overall mixture and micelles, whereas the interaction is attractive if DTAB is in excess. At α SPFO = 0.38 the low miscibility between hydrocarbon and fluorocarbon is counterbalanced by the electrostatic attraction between the opposite charged head groups, and the micelle composition is ideal (i.e., the mole fraction of SPFO in micelles X SPFO = α SPFO = 0.38 ). The solubility of fluorocarbon in hydrocarbon is lower than that of hydrocarbon in fluorocarbon. Micelles of DTAB act as a solvent for SPFO without important structural changes, whilst micelles of SPFO undergo important changes when dissolve DTAB. This asymmetry may be interpreted as caused by the difference in chain length that favors the inclusion of the shorter chain in micelles of the longer surfactant, but disfavors the opposite process. Above X SPFO = 0.5 there is an excess adsorption of Bromide ions on the mixed micelles surface, giving rise to a high ζ potential. Micelles of pure SPFO or pure DTAB show an important energy barrier which prevents micelle flocculation. The inclusion of SPFO in DTAB micelles produces a reduction of the energy barrier, which disappeared when α SPFO = 0.5 . This produces the flocculation of micelles giving rise to the formation of a non-birefringent coacervate, which is probably formed by unordered isometric clusters of micelles.
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The aqueous catanionic system sodium perfluorooctanoate–Dodecyltrimethylammonium Bromide at low concentration
Journal of Colloid and Interface Science, 2007Co-Authors: José L. López-fontán, Pablo C. Schulz, Juan M. Ruso, Gerardo Prieto, Elena Blanco, Félix SarmientoAbstract:Abstract The interaction between sodium perfluorooctanoate (SPFO) and Dodecyltrimethylammonium Bromide (DTAB) was studied by several methods and it was found strongly synergistic. Above a mole fraction of SPFO in the surfactant mixture ( α SPFO ) = 0.38 , the interaction is repulsive and increases with the content of SPFO in both, the overall mixture and micelles, whereas the interaction is attractive if DTAB is in excess. At α SPFO = 0.38 the low miscibility between hydrocarbon and fluorocarbon is counterbalanced by the electrostatic attraction between the opposite charged head groups, and the micelle composition is ideal (i.e., the mole fraction of SPFO in micelles X SPFO = α SPFO = 0.38 ). The solubility of fluorocarbon in hydrocarbon is lower than that of hydrocarbon in fluorocarbon. Micelles of DTAB act as a solvent for SPFO without important structural changes, whilst micelles of SPFO undergo important changes when dissolve DTAB. This asymmetry may be interpreted as caused by the difference in chain length that favors the inclusion of the shorter chain in micelles of the longer surfactant, but disfavors the opposite process. Above X SPFO = 0.5 there is an excess adsorption of Bromide ions on the mixed micelles surface, giving rise to a high ζ potential. Micelles of pure SPFO or pure DTAB show an important energy barrier which prevents micelle flocculation. The inclusion of SPFO in DTAB micelles produces a reduction of the energy barrier, which disappeared when α SPFO = 0.5 . This produces the flocculation of micelles giving rise to the formation of a non-birefringent coacervate, which is probably formed by unordered isometric clusters of micelles.
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The nature of the coacervate formed in the aqueous Dodecyltrimethylammonium Bromide–sodium 10-undecenoate mixtures
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006Co-Authors: María Belén Sierra, Marcela A. Morini, Pablo C. Schulz, Paula V. Messina, Juan M. Ruso, Gerardo Prieto, Félix SarmientoAbstract:Abstract 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.
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the nature of the coacervate formed in the aqueous Dodecyltrimethylammonium Bromide sodium 10 undecenoate mixtures
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006Co-Authors: María Belén Sierra, Marcela A. Morini, Pablo C. Schulz, Paula V. Messina, Juan M. Ruso, Gerardo Prieto, Félix SarmientoAbstract:Abstract 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.
R Triolo - One of the best experts on this subject based on the ideXlab platform.
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effect of crown ether 1 4 7 10 13 16 hexaoxacyclooctadecane on the structure of sodium dodecyl sulfate and Dodecyltrimethylammonium Bromide aqueous micellar solutions
Langmuir, 1995Co-Authors: Eugenio Caponetti, Michele Floriano, R Triolo, Chillura D Martino, G D WignallAbstract:The effects of the addition of crown ether 1,4,7,10,13,16-hexaoxacyclooctadecane on the structure of aqueous solutions of surfactants sodium dodecyl sulfate and Dodecyltrimethylammonium Bromide have been studied by small angle neutron scattering. By modeling the scattering intensities, it was possible to derive, simultaneously, both structural properties and information on the distribution of crown ether between the micellar and aqueous phases. In the case of sodium dodecyl sulfate, an appreciable amount of crown ether was found to be localized in the micellar phase, though it was not possible to establish whether it was in the core or in the shell ; there was no evidence of crown ether localization in Dodecyltrimethylammonium Bromide micelles. The above observations indicate that although, at least in principle, the crown ether methylene groups could interact hydrophobically in the micellar core with the surfactant alkyl chains, the ability of crown ethers to form metal complexes might also lead, in sodium dodecyl sulfate solutions, to electrostatic interactions in the external palisade between the crown ether-sodium ion complex and the surfactant head groups. The absence of crown ether from Dodecyltrimethylammonium Bromide micelles indicates that the macrocyclic molecules interact with sodium dodecyl sulfate micelles via the formation of a complex between the sodium ion and the crown ether and rules out the possibility of hydrophobic interaction in the micellar core.
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Dodecyltrimethylammonium Bromide in water urea mixtures structure and energetics
The Journal of Physical Chemistry, 1992Co-Authors: Eugenio Caponetti, S. Milioto, R. De Lisi, S Causi, Michele Floriano, R TrioloAbstract:Enthalpies of dilution and osmotic coefficients of Dodecyltrimethylammonium Bromide (DTAB)-water-urea mixtures as functions of urea (m u ) and surfactant (m g ) concentrations were measured at 298 and 310 K. Small-angle neutron scattering (SANS) measurements were also performed on some DTAB-D 2 O-urea mixtures at two surfactant concentrations and different urea concentrations at 298 K. From the thermodynamic data, the apparent (L Φ ) and partial molar relative enthalpies (L 2 )