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91.
The conductances of sodium dodecylsulphate (SDS) + sodium decylsulfate (SDeS) and decyltrimethylammonium bromide (DeTAB) + tetradecyltrimethylammonium bromide (TTAB) over the entire mole fraction range of SDS (SDS) or DeTAB (DeTAB) were measured in water, 18-crown-6 ether + water (CR + W) and -cyclodextrin + water (CYC + W) mixtures at fixed 4 mM and 8 mM of CR or CYC in their respective binary mixtures at 30 °C. The conductivity plots for SDS + SDeS mixtures show a single break whereas two breaks are observed at most of the DeTAB for DeTAB + TTAB mixtures. From the break in the conductivity data, the mixed critical micellar concentration (cmc) and degree of counter-ion association () were computed. The first break corresponds to the classical cmc of TTAB is termed as the first cmc (C1) and the second break which is observed at concentrations about 4 times the first one, corresponding to the classical cmc of DeTAB and is considered to be the second cmc (C2). The non-ideality in SDS + SDeS mixtures has been evaluated by using the regular solution theory and it has been observed that the mixture is close to ideal in the absence and presence of additives. The variation in C1, C2 and 1, 2 for DeTAB + TTAB has been discussed in terms of the mixed micelle formation which are predominantly rich in the TTAB and DeTAB monomers respectively. 相似文献
92.
This paper presents the results of morphological and ac electrical investigations on low density polyethylene (LDPE) composites with octavinyl polyhedral oligomeric silsesquioxane (POSS). It has been shown that at low loadings, the frequency dependence of dielectric constant and dielectric loss for the LDPE/POSS composites showed unusual behaviors when compared with conventional (micro-sized particulates) composites. The ac breakdown strength was measured and statistical analysis was applied to the results to determine the effects of POSS loadings on the dielectric strength of LDPE. The morphological characterization showed that the presence of POSS additives apparently altered the supermolecular structure of LDPE and resulted in more homogeneous morphology when compared with the neat LDPE. The structure-property relationship was discussed and it was concluded that the final dielectric properties of the composites were determined not only by the incorporation of POSS additives but also by the supermolecular structure of LDPE. Rheological analyses of LDPE/POSS composite were also performed and the results showed that the octavinyl-POSS had good compatibility with LDPE. 相似文献
93.
94.
The reaction of 1,8-diamino-3,6-diazaoctane and diethyl malonate in dry methanol yielded a 13-membered macrocycle. Complexes
of the type [Ln(tatd)Cl2 (H2O)3]Cl [LnIII=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy; tatd=1, 5, 8, 11-tetra-azacyclotridecane-2,4-dione] have been synthesized by template condensation.
The complex [La(tatd)Cl2 (H2O)3]Cl in methanol was reacted with lanthanide chlorides to yield the trinuclear complexes of type [2{La(tatd)Cl2(H2O)3}LnCl3]Cl2 [LnIII=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy]. The chemical compositions of mono and trinuclear complexes have been established on the
basis of analytical, molar conductance, electrospray (ES) and fast atom bombardment (FAB) mass data. In mononuclear complexes
the Ln3+ ion is encapsulated by four ring nitrogens and in trimetallic complexes the exo-carbonyl oxygens of two mononuclear units
coordinate to the Ln3+ ions resulting in a polyhedron around the lanthanide ions. Thus the macrocycle is bonded in a tetradentate fashion in the
former complexes and hexadentate in the latter. The coordination number nine around the encapsulated Ln3+ and seven around the exo-oxygen bonded Ln3+ ions are established. The symmetry of the ligand field around the metal ions is indicated from the emission spectra. 相似文献
95.
96.
Guang‐Ri Xu Xin‐hua Qi Fengxia Yang Jae‐Joon Lee Ming‐Lu Xu Yu‐Ping Zhang Sunghyun Kim 《Electroanalysis》2009,21(22):2486-2490
A glassy carbon electrode having two polymer layers has been applied to selectively detect epinephrine. The inner layer formed by electropolymerization of macrocyclic nickel complex functioned as an electrocatalyst for epinephrine oxidation and the outer layer composed of hydrolyzed polyurethane γ‐benzyl L ‐glutamate as a screening layer. Differential pulse voltammetry showed almost 100% recovery of epinephrine even in 100‐fold excess of interferents. When applied to a dual glassy carbon electrode as an amperometric detector in flow injection analysis, a linear response over 0.1 μM and 10 μM was obtained. Recovery tested for 5‐fold diluted human urine samples was 97.5%. 相似文献
97.
Ying‐Ling Liu Min‐Chi Tseng Meng‐Han Fangchiang 《Journal of polymer science. Part A, Polymer chemistry》2008,46(15):5157-5166
Thermally induced polymerization of multifunctional methylmethacrylate POSS (MMA‐POSS) was studied in this work for preparation of polymer/POSS nanocomposites. The polymerization of MMA‐POSS could be promoted with benzoyl peroxide (BPO). Self‐assembly of POSS into a layer‐by‐layer structure in the MMA‐POSS polymer (TP‐MMA‐POSS) is observed with a transmission electron microscopy. An ultra‐low‐k value of about 1.85 is measured with TP‐MMA‐POSS. In addition, polyimide‐POSS nanocomposites are also prepared. These nanocomposites demonstrate good homogeneity and enhanced mechanical properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5157–5166, 2008 相似文献
98.
Akira Matsumoto Hiroyuki Hamamoto Yuta Miwa Hiroyuki Aota Satoshi Inoue Katsutoshi Yokoyama Yasuo Matoba Michirou Shibano 《Journal of polymer science. Part A, Polymer chemistry》2009,47(11):2871-2881
No difference in the actual gel points was substantially observed among three isomeric diallyl phthalates such as diallyl phthalate (DAP), diallyl isophthalate, and diallyl terephthalate (DAT); this interesting gelation behavior was discussed further in terms of the correlation between gelation and the difference in cyclization modes, and also, the difference in reactivity between the uncyclized and cyclized radicals for cross‐linking. In the present work, we tried to extend the preceding discussion to the polymerization of triallyl trimellitate (TAT) because the molecular structure of TAT is presumed to essentially involve the characteristics of three isomeric diallyl phthalates and, therefore, the enhanced gelation was expected in TAT polymerization. However, no enhancement of gelation was observed. For a full understanding of the gelation in multiallyl cross‐linking polymerization, we explored further the polymerizations of DAP, DAT, and TAT, especially focusing on the characterization of resultant network polymer precursors (NPPs) using SEC‐MALLS‐viscometry providing the correlation of [η] versus Mw of fractionated samples. Notably, the structure of NPP consisting of oligomeric primary polymer chains generated from specific allyl polymerization would become core‐shell type dendritic with the progress of polymerization. The correlation between delayed gelation and decreased reactivity of dendritic NPP for intermolecular cross‐linking is discussed. Conclusively, the reactivity for intermolecular cross‐linking between NPPs decreased with the progress of polymerization leading to a delayed gelation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2871–2881, 2009 相似文献
99.
100.
Toxic metal complexes of macrocyclic cyclen molecule – synthesis,structure and complexing properties
M. Litecká R. Gyepes M. Vilková M. Almáši M. Walko 《Journal of Coordination Chemistry》2017,70(10):1698-1712
Toxic metal (Cd2+, Hg2+, Pb2+, and Ag+) complexes with the tetradentate macrocyclic ligand - cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN4, L) were prepared and studied in the solid state by IR, X-ray diffraction, elemental and thermal analysis. Diffraction results have yielded three molecular structures, [Cd([12]ane-κ4N1,4,7,10)(NO3)2)] (1), [Hg([12]ane-κ4N1,4,7,10)(NO3-κ2O,O`)]NO3 (2), [Pb2([12]ane-κ4N1,4,7,10)2][Pb(NO3)6] (3) and one polymeric structure {[Ag2([12]ane-κ3N1,4,7)(μ2-[12]aneN10)](NO3)2?2H2O)}n (4) featuring a unique coordination mode not observed before with cyclen as a ligand. The monodentate (1) and chelate (with small bite angle 50.3(3)°, (2) coordination modes of nitrate ligands were confirmed. Stereochemically active 6s2 lone pair was suggested in 3 and DFT results confirmed no significant metal–metal covalent bond. The stability constants of the complexes with Cd2+ and Pb2+ ions were determined by potentiometric methods in aqueous solutions. Additionally, the structures of complexes in solution were observed by 1H NMR. Both methods confirm similar cyclen complexing properties toward Zn2+ biometal and Cd2+, Pb2+ toxic metals. 相似文献