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Title: Phase behavior and microstructures of the Gemini(12-3-12,2Br-)-SDS-H20 ternary

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COLLABORATION - East china U. of Science andTechnology/China
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Journal Article
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Journal Name: Colloids and Surfaces A; Journal Volume: 294; Related Information: Journal Publication Date: 2007
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United States

Citation Formats

Shang, Yazhuo, Liu, Honglai, Hu, Ying, and Prausnitz, John M. Phase behavior and microstructures of the Gemini(12-3-12,2Br-)-SDS-H20 ternary. United States: N. p., 2005. Web.
Shang, Yazhuo, Liu, Honglai, Hu, Ying, & Prausnitz, John M. Phase behavior and microstructures of the Gemini(12-3-12,2Br-)-SDS-H20 ternary. United States.
Shang, Yazhuo, Liu, Honglai, Hu, Ying, and Prausnitz, John M. Fri . "Phase behavior and microstructures of the Gemini(12-3-12,2Br-)-SDS-H20 ternary". United States. doi:.
title = {Phase behavior and microstructures of the Gemini(12-3-12,2Br-)-SDS-H20 ternary},
author = {Shang, Yazhuo and Liu, Honglai and Hu, Ying and Prausnitz, John M.},
abstractNote = {},
doi = {},
journal = {Colloids and Surfaces A},
number = ,
volume = 294,
place = {United States},
year = {Fri Dec 02 00:00:00 EST 2005},
month = {Fri Dec 02 00:00:00 EST 2005}
  • Phase behavior and microstructures have been investigated for aqueous mixtures of cationic Gemini surfactant (12-3-12,2Br{sup -}) and anionic surfactant sodium dodecyl sulfate (SDS) using freeze-etching and negative-staining and with transmission electron microscopy (TEM). The phase diagram shows different regions characterized by different microstructures. Most of the regions are occupied by multi-lamellar phases in which vesicles coexist with micelles when the solutions are dilute. The multi-lamellar vesicles have higher stability because of their special structures. The ratio of vesicles to micelles varies with concentration and composition of the mixed-surfactant solutions. At higher surfactant concentrations, we observe other phases: the lamellar phase,more » anisotropic phase, aqueous two-phase system (ATPS), rod-like micelle phase, as well as other unique microstructures such as cylindrical micelles formed by short rod-like micelles, and porous morphology. Observations are reported for the transformation among different phases, especially from rod-like to spherical micelles.« less
  • Two phases coexist in an aqueous system that contains the two surfactants cationic gemini 12-3-12,2Br- and anionic SDS. An aqueous two-phase system (ATPS) is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic-anionic surfactant systems. In that region, the molar ratio of gemini to SDS varies with the total concentration of surfactants. ATPS not only has higher stability but also has longer phase separation time for the new systems than that of the traditional system. Furthermore, the optical properties of ATPS are different at different total concentrations. All of these experimental observationsmore » can be attributed to the unique properties of gemini surfactant and the synergy between the cationic gemini surfactant and the anionic surfactant SDS.« less
  • Investigations on phase relationships and crystal structures have been conducted on several ternary rare-earth titanium antimonide systems. The isothermal cross-sections of the ternary RE-Ti-Sb systems containing a representative early (RE=La) and late rare-earth element (RE=Er) have been constructed at 800 deg. C. In the La-Ti-Sb system, the previously known compound La{sub 3}TiSb{sub 5} was confirmed and the new compound La{sub 2}Ti{sub 7}Sb{sub 12} (own type, Cmmm, Z=2, a=10.5446(10) A, b=20.768(2) A, and c=4.4344(4) A) was discovered. In the Er-Ti-Sb system, no ternary compounds were found. The structure of La{sub 2}Ti{sub 7}Sb{sub 12} consists of a complex arrangement of TiSb{sub 6}more » octahedra and disordered fragments of homoatomic Sb assemblies, generating a three-dimensional framework in which La atoms reside. Other early rare-earth elements (RE=Ce, Pr, Nd) can be substituted in this structure type. Attempts to prepare crystals in these systems through use of a tin flux resulted in the discovery of a new Sn-containing pseudoternary phase RETi{sub 3}(Sn{sub x}Sb{sub 1-x}){sub 4} for RE=Nd, Sm (own type, Fmmm, Z=8; a=5.7806(4) A, b=10.0846(7) A, and c=24.2260(16) A for NdTi{sub 3}(Sn{sub 0.1}Sb{sub 0.9}){sub 4}; a=5.7590(4) A, b=10.0686(6) A, and c=24.1167(14) A for SmTi{sub 3}(Sn{sub 0.1}Sb{sub 0.9}){sub 4}). Its structure consists of double-layer slabs of Ti-centred octahedra stacked alternately with nets of the RE atoms; the Ti atoms are arranged in kagome nets. - Graphical abstract: La{sub 2}Ti{sub 7}Sb{sub 12} contains sectioned layers consisting of Ti-centred octahedra linked by corner- and face-sharing.« less
  • Electron spin echo modulation (ESEM) of x-doxylstearic acid spin probes (x-DSA, x = 5, 7, 10, 12, and 16) in mixed micellar solutions of ionic and nonionic surfactants has been studied as a function of the doxyl position along the alkyl chain of the stearic acid spin probe and of the mixed micellar composition. The mixed micellar systems investigated were sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DTAC) with hexakis(ethylene glycol) monododecyl ether (C[sub 12]E[sub 6]), selectively deuterated along the poly(ethylene glycol) group (C[sub 12]D[sub 6]) or along the alkyl chain ((CD)[sub 12]E[sub 6]) in H[sub 2]O and D[sub 2]O.more » The average probe conformation and probe location in the pure surfactants and in the mixed micelles are reported as a function of the doxyl position, x. Modulation effects due to the interactions of the probe unpaired electron with deuterium in D[sub 2]O give direct evidence that the hydration is maximized for an equimolar mixture of SDS/C[sub 12]E[sub 6] mixed micelles. It is also found that the polar head groups of SDS and DTAC surfactants are located in the ethylene oxide region of the C[sub 12]E[sub 6] surfactant. A comparative analysis of the deuterium modulation depth, arising from deuteriums located in the alkyl chain or in the ethylene oxide groups of the nonionic surfactant, shows that SDS polar head groups are located at the surface of the mixed micelle, close to the second ethylene oxide group of C[sub 12]E[sub 6], while DTAC polar head groups are located deeper inside the mixed micelle, at the 5th-6th ethylene oxide group of the nonionic surfactant. These results provide an explanation at the molecular level of the different thermodynamical behavior found for mixed micelles of anionic-nonanionic and cationic-nonionic surfactants. 44 refs., 8 figs.« less
  • Al{sub 2−2x}(ZrMg){sub x}W{sub 3}O{sub 12} for 0≤x≤1.0 are synthesized to reduce the phase transition temperature of Al{sub 2}W{sub 3}O{sub 12}. It is found that the incorporation of (ZrMg){sup 6+} into the lattice of Al{sub 2}W{sub 3}O{sub 12} not only reduces its orthorhombic-to-monoclinic phase transition temperature but also elevates its softening temperature, broadening its applicable temperature range considerably. Al{sub 2−2x}(ZrMg){sub x}W{sub 3}O{sub 12} with x<0.5 exhibit low coefficients of thermal expansion (CTEs) and non-hygroscopicity, while those for x≥0.7 are obviously hygroscopic and the CETs decrease with increasing the content of (ZrMg){sup 6+} so that Al{sub 0.2}(ZrMg){sub 0.9}W{sub 3}O{sub 12} and ZrMgW{submore » 3}O{sub 12} exhibit negative thermal expansion. Temperature-dependent Raman spectroscopic study shows the hardening of W–O bonds above 373 K which is attributed to the release of crystal water. The effect of crystal water on the thermal expansion property is discussed based on the hydrogen bond between H in crystal water and electronegative O in Al(ZrMg)–O–W linkages. - Graphical abstract: (a and b) Temperature dependent Raman spectra of Al{sub 2−x}(ZrMg){sub x}W{sub 3}O{sub 12} (x=0.1, 0.2), (c and d) Building block of a unit cell of Al{sub 2−x}(ZrMg){sub x}W{sub 3}O{sub 12}·n(H{sub 2}O) and schematic showing the effect of crystal water on Al(Zr, Mg)–O–W linkages. - Highlights: • (ZrMg){sup 6+} reduces orthorhombic-to-monoclinic phase transition of Al{sub 2}W{sub 3}O{sub 12}. • The incorporation of (ZrMg){sup 6+} elevates the softening temperature of Al{sub 2}W{sub 3}O{sub 12}. • Al{sub 2−2x}(ZrMg){sub x}W{sub 3}O{sub 12} (x<0.5) exhibit low CTEs and non-hygroscopicity. • Al{sub 0.2}(ZrMg){sub 0.9}W{sub 3}O{sub 12}·0.8H{sub 2}O and ZrMgW{sub 3}O{sub 12}·2H{sub 2}O present NTE. • Hydrogen bond between H in H{sub 2}O and O in Al(ZrMg)–O–W affects thermal expansion.« less