- Micelle-to-vesicle transition induced by organic additives in catanionic surfactant systems
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A micelle-to-vesicle transition (MVT) induced by the addition of a series of apolar hydrocarbons (n-butylbenzene, n-hexane, n-octane, and n-dodecane) to the catanionic surfactant system n-dodecyltriethylammonium bromide/sodium n-dodecylsulfate (DTEAB/SDS) has been investigated for the first time by means of rheology and turbidity measurements, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Interestingly, a MVT can take place within certain micellar regions, which are dependent on the structure and chain length of the hydrocarbon. However, these hydrocarbons are unable to induce a MVT in another catanionic surfactant system, namely, n-dodecyltriethylammonium bromide/sodium n-dodecylsulfonate (DTEAB/SDSO3), in which the molecular interactions are weaker than in the DTEAB/SDS system. On the other hand, polar additives, such as n-octanol and n-octylamine, exhibit much higher efficiency and activity in inducing MVT than hydrocarbons in both DETAB/SDS and DTEAB/SDSO3. Moreover, DLS, TEM, and time-resolved fluorescence quenching (TRFQ) results demonstrate that the ratio of vesicles to micelles in the system can be actively controlled by addition of polar additives. Possible mechanisms for the above phenomena are presented, and the potential application of controllable micelle/vesicle systems in the synthesis of tailored bimodal mesoporous materials is discussed.
- Yin, Haiqing,Lei, Sheng,Zhu, Shengbao,Huang, Jianbin,Ye, Jianpin
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- Heating-induced micelle to vesicle transition in the cationic-anionic surfactant systems: Comprehensive study and understanding
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Heating-induced micelle to vesicle transition (MVT), which has been rarely reported in surfactant systems, was systemically studied in a number of mixed cationic-anionic surfactant systems. According to the turbidity measurements, the investigated systems can be divided into two classes: Class A and B. Heating-induced MVT was observed in Class A at certain total surfactant concentrations and mixed surfactant ratios, while no such transition was found in Class B. Further investigations revealed that the heating-induced MVT is more likely to take place in the cationic-anionic surfactant systems with relatively stronger molecule interaction and larger micelle aggregation number. The effects of several physicochemical factors, such as the variation of mixed surfactant ratios and the addition of n-decanol on the heating-induced MVT, were also studied. ? 2005 American Chemical Society.
- Yin, Haiqing,Huang, Jianbin,Lin, Yiyang,Zhang, Yongyi,Qiu, Shunchen,Ye, Jianping
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- Highly ordered supermicroporous aluminosilicates with cubic Pm3n symmetry fabricated in weakly acidic solution
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Highly ordered supermicroporous aluminosilicates with cubic Pm3n symmetry were prepared for the first time in weakly acidic solutions of succinic acid and malonic acid using dodecyltriethylammonium bromide as a template. The polycarboxylic acids acted as auxiliaries for fabricating the cubic Pm3n structure as well as weak acids. Thermally stable aluminosilicates with a high utilization ratio of Al could be obtained in the presence of succinic acid by either facilely adding aluminum source into the initial synthesis gel or by grinding the as-made silica-surfactant composite with aluminum nitrate. In contrast, thermally stable aluminosilicates could only be prepared via a post-synthesis approach in the presence of malonic acid, probably because of the powerful coordination tendency between malonic acid and Al cations. The thermal stability of the aluminosilicates was enhanced because of the incorporation of Al into the framework or grafting of Al onto the pore walls. Aluminosilicates prepared via the post-synthesis approach preserved the cubic Pm3n structure better than the directly-synthesized ones. In spite of the kind of polycarboxylic acids or the preparation methods, Al was predominantly tetrahedrally coordinated. The aluminosilicates showed a high specific area and pore volume, especially for the post-synthesized ones. The pore size was in the supermicroporous range evidenced by N2 physisorption, though that of the aluminosilicates prepared via the post-synthesis approach was larger. TEM images verified the Pm3n symmetry of the materials herein. The cubic Pm3n aluminosilicates prepared in our research exhibited equal reactivity but a much pronounced deactivation resistance property in the acetalization of cyclohexanone with pentaerythritol.
- Fu, Wen Hua,Wang, Yi Meng,He, Ming Yuan
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- Effect of the surfactant head-group size dependence of the dye-surfactant interactions on the lyotropic uniaxial to biaxial nematic phase transitions
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In the present study, the interactions of the anionic azo dye Sunset Yellow with dodecylalkylammonium bromide (DAABr) surfactants in lyotropic mixtures have been investigated for the stabilization of the different lyotropic nematic phases. Sunset Yellow doped mixtures of DAABr surfactants, with different head-group size, were studied by polarizing optical microscopy, laser conoscopy, and small-angle X-ray scattering. It was found that the extent of the interaction of Sunset Yellow with DAABr surfactant head groups on micelle surfaces affects the stabilization of different nematic phases, by causing the change in the micellar structural parameters. The results also indicated that the micelle surface curvature should be different in the three nematic phases.
- Akpinar, Erol,Uygur, Nazli,Ordu, Oznur Demir,Reis, Dennys,Neto, Ant?nio Martins Figueiredo
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- New chemical family of [n-CxH(2X+1)Net3][BeT3Me] showing ionic plastic-crystal (x = 4, 5), rotator-crystal (x = 6, 7) and liquid-crystal phases (X = 816)
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New ionic liquid crystals of [n-CxH(2x+1)NEt3][BEt3Me] (abbreviated to [CxNEt3][BEt3Me]) were detected for species with even numbers of 8 ˉ x ˉ 16. In contrast, plastic- and rota
- Yamada, Yudai,Kashimoto, Erina,Honda, Hisashi
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p. 1289 - 1298
(2019/09/18)
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- Improving Cellulose Dissolution in Ionic Liquids by Tuning the Size of the Ions: Impact of the Length of the Alkyl Chains in Tetraalkylammonium Carboxylate
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Twenty ionic liquids based on tetraalkylammonium cations and carboxylate anions have been synthesized, characterized, and tested for cellulose dissolution. The amount of cellulose dissolved in these ionic liquids depends strongly on the size of the ions:
- Meng, Xiangqian,Devemy, Julien,Verney, Vincent,Gautier, Arnaud,Husson, Pascale,Andanson, Jean-Michel
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p. 1749 - 1760
(2017/04/27)
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- Investigation of cationic surfactants and sulfonamides and their nanoparticles as biocides against sulfur reducing bacteria in the petroleum industry
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A series of cationic ammonium surfactants (1-3) and sulfonamides (4-5) were synthesized and characterized using elemental analysis and FT-IR spectroscopy. The nanostructures of the synthesized surfactants and sulfonamides as silver and zinc nanoparticles
- Morsy, Salwa M. I.,Ibrahim, Mohamed M.
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p. 530 - 536
(2014/01/06)
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- Surface properties and aggregates in the mixed systems of bolaamphiphiles and their oppositely charged conventional surfactants
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Two transition points were observed in the surface tension curves of the mixed systems of cationic bolaamphiphile BPHTAB (biphenyl-4,4′- bis(oxyhexamethylenetrimethylammonium bromide)) and its oppositely charged conventional surfactants. Transmission electron microscopy, dynamic light scattering, and isothermal titration microcalorimetric experiments demonstrated that spherical vesicles or elongated aggregates formed at the lower surfactant concentration than the corresponding critical micelle concentration (cmc), which led to the existence of two transition points in surface tension curves. Addition of 10% formamide into the mixed system broke the vesicles and elongated aggregates and made the first breaking point disappear. The biphenyl group in the BPHTAB molecule and the appropriate attractive interaction between the cationic and anionic headgroups of the surfactants had a great influence on the ability of vesicle formation and determined whether the two transition points would exist in the surface tension curve.
- Han, Feng,He, Xiao,Huang, Jianbin,Li, Ziehen,Wang, Yilin,Fu, Honglan
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p. 5256 - 5262
(2007/10/03)
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- Synthesis of ω-hydroxy quaternary ammonium bolaform surfactants
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Several members of a novel class of ω-substituted asymmetric bolaform surfactants have been synthesized in order to investigate their surfactant and biological properties. The ω-hydroxy trialkylammonium and pyridinium surfactants have significant antimicrobial and antifungal activity relative to their conventional analogues. For conventional quaternary ammonium alkyl surfactants, increasing the hydrocarbon chain length causes a decrease in the surfactant monomer solubility and a corresponding decrease in the biological activity. No such trend is observed for the ω-hydroxy quaternary ammonium bromide series.
- Davey, Tim W.,Hayman, Alan R.
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p. 581 - 586
(2007/10/03)
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- Aggregation of cationic surfactants in D2O: A proton NMR study on effects of the structure of the headgroup
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Aggregation of the following surfactants in D2O has been studied by 1H NMR spectroscopy at 500.13MHz, 298 K: series I, dodecyltrialkylammonium bromides, alkyl group = methyl, ethyl, n-propyl, and n-butyl; series II, dodecyldimethyl (2-hydroxyethyl)ammonium bromide, dodecylmethyl bis(2-hydroxyethyl)ammonium bromide, and dodecyl tris(2-hydroxyethyl)ammonium bromide. Chemical shifts of the surfactant discrete groups were measured at concentrations below and above the surfactant critical micelle concentration, c.m.c., whose value was determined by conductance measurements in H2O. Plots of observed chemical shifts versus [surfactant] are sigmoidal, and were fitted to a model based on the mass-action law. Excellent fits were obtained for the discrete groups of all surfactants. The parameters determined by these fits were: the equilibrium constant for micelle formation, K, c.m.c., and the chemical shifts of the monomer, δmon and the micelle, δmic. 1H NMR-based c.m.c. values are in excellent agreement with those which we determined by conductance measurements. Values of K increase as a function of increasing the size of the headgroup of series I surfactants, but the incremental contribution to the Gibbs free energy per CH2 group at the interface is small, its value increases from 0.13 kJ (moles of CH2)-1 to 0.29kJ (moles of CH2)-1 in going from the trimethyl- to the tri-n-propyl, and the tri-n-butyl analogue, respectively. Micellization affects the chemical shifts of the groups at, or near to, the interface mainly because of differences in hydration of the surfactant molecule in its monomeric and aggregated forms. This conclusion is supported by comparing (δmic: - δmic) with (δCDCl3 δmic) where δmicCDCl3 is the chemical shift of the surfactant in CDCl3, i.e., in absence of hydration. For series II surfactants, the chemical shifts versus [surfactant] plots are qualitatively similar to those for series I, this shows that substitution of the 2-hydroxyethyl group for the ethyl group in the hydrophilic part of the surfactant does not seem to change the properties of the formed aggregate. WILEY-VCH Verlag GmbH, 1997.
- Bazito, Reinaldo C.,El Seoud, Omar A.,Barlow, Graham K.,Halstead, Tom K.
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p. 1933 - 1941
(2007/10/03)
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- The Effect of Cationic Detergents on the Spectral Properties of Pontachrome Azur blue and its Metal(III)-complexes - Micell Effect or Ternary Complex Formation ?
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The results of studies of the metachromasy effect of pontachrome azur blue and its lakes, preferably with aluminium, and hexadecyl-, tetradecyl-, dodecyl- and decyltriethyl-ammonium-bromide, respectively can be explained on the basis of ternary complex formation.The surfactants can be applied at concentrations far below its critical micelle concentrations thus excluding micelle effects.
- Seidel, A.,Hoyer, E.
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p. 299 - 308
(2007/10/02)
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