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Showing 1 to 20 of 20 for “"29Si-NMR"”.
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The sol-gel polymerization of octamethoxysilsesquioxane
… the polymerization was followed by 29Si NMR spectroscopy, which indicated that the cubic structure of [SigOi2](OCH3)g was retained under initial polymerization conditions. Polymerization under acidic conditions was much slower than under basic or neutral conditions. The 29Si NMR …
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Síntese e caracterização de um novo agente sililante - imobilização na sílica gel em meio aquoso.
… analysis of CHNS, infrared spectroscopy, NMR 13C and 29Si, thermogravimetric analysis and surface area. The surface area were 0.43 m2g-1 and 193 for solids AMPTGA and Sil-AMPTGA, respectively, which were lower than that of silica gel precursor 484 m2g-1. The thermogravimetric analysis …
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Contributions to the chemistry of higher-coordinate Silicon : synthesis, structure, and stereodynamics of new Silicon(IV) complexes with SiO2N2C, SiO4C, or SiO6 skeletons
… (C, H, N), crystal structure analyses, 15N and 29Si VACP/MAS solid-state NMR experiments) and in solution (except 10; 1H, 13C, and 29Si NMR experiments)The spirocyclic zwitterionic Lambda5Si-silicates 13, 15, and 16 with an (ammonio)methyl group and two bidentate meso-oxolane-3,4-diolato(2–) …
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Understanding effects of silicon/aluminum ratio and calcium hydroxide on chemical composition, nanostructure and compressive strength for metakaolin geopolymers
… calcium silicate hydrate in XRD patterns. Both 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS-NMR) were used to quantitatively observe the individual silicon and aluminum structures in the different phases in the geopolymer. From 29Si NMR analysis, the composition and amount …
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Chemical vapor deposition of organosilicon and sacrificial polymer thin films
… spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy were utilized to characterize film structure and understand the relationship between the structure and properties of materials. Computational quantum mechanics is a power tool applied to explain observed phenomena such as …
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Lewis Base Activation of Lewis Acids in Asymmetric Aldol Reactions of Silyl Ketene Acetals
… the phosphoramide bound silyl cation complex by 29Si NMR.
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Beiträge zur Chemie des höherkoordinierten Siliciums: Synthese, Struktur und Eigenschaften neuer Silicate mit SiO 3 C 2 -, SiO 4 C -, SiO 5 - und SiO 6 -Gerüst, Beiträge zur Chemie des tetrakoordinierten Siliciiums: Synthese, Struktur und Eigenschaften von Silanen, Silanolen und Siloxanen
… dem bereits bekannten l5Si-Silicat 1 durch 1H-VT-NMR-Experimente die Energiebarriere für die Enantiomerisierung im Sinne einer Berry-Pseudorotation in Lösung bestimmt werden. Durch Hydrolyse von 1 — gefolgt von Kondensationsreaktionen — wurde das neuartige Oktasilsesquioxan 2 dargestellt. Die …
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Hydrophobic, fluorinated silica xerogel for low-k applications.
… was analyzed using high-resolution liquid 29Si NMR. It was found that after several hours, DMDES hydrolyzed and condensed into linear and cyclic species. Films from triethoxyfluorosilane (TEFS) have been shown to be promising interlayer dielectric materials for future integrated circuit …
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Neue Alkin-1-ylsilane und -germane, Sila- und Germacyclopentadiene – Charakterisierung mittels Multikern-NMR-Spektroskopie
… -germane darge-stellt und anhand der Multikern-NMR-Spektroskopie untersucht. Besonders gut lässt sich der Verlauf der Substitution durch 29Si-NMR-Spektroskopie detektieren, selbst in verdünnten Lösungen und komplexen Mischungen. Bei der Darstellung wurden normalerweise Produktmischungen erhalten …
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ORMOCER (inorganic-organic hybrid polymer)-zeolite Nanocomposites: Advanced Membrane Materials for Gas Separation
… were analysed using FT-IR, liquid-state 29Si NMR, TG, DSC, SEM, N2 sorption and single-gas permeation measurements. The permeation performance of the membranes was examined using H2, He, CO2, O2 and N2 as a test gases at room temperature, the upstream pressure was varied between 1.3 to …
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Complexation of Block Copolysiloxanes with Cobalt Nanoparticles
… well with experimental values determined by 1H NMR, 29Si NMR, and GPC. Morphologies were investigated by DSC to analyze glass transition temperatures. Only one Tg was observed for each PDMS-b-PMVS block copolymer suggesting that the blocks were miscible in bulk. Tg's ranged from approximately …
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Inorganic-Organic Sol-Gel Derived Hybrid Materials as Abrasion Resistant Coatings
… (3-APS) primer. FT-IR, GPC, 1H and 13C NMR, XPS experiments were conducted to support this mechanism. The f-DETA/TMOS system is essentially a binary system of an alkyltriethoxysilane (T) and a tetraalkoxysilane (Q). At pH 0-2 and pH 4-5, the relative condensation reactivities of the T …
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Hyperbranched polyalkoxysiloxanes, synthesis, characterization and applications
… are liquids and soluble in organic solvents. NMR and MALDI-ToF-MS analysis showed that the polymers obtained by the silanol route have a hyperbranched structure with some cycle formation. Rather similar polymers could be synthesized by the acetoxyroute, which is technologically much more …
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The preparation and characterisation of highly selective adsorbents for fission product removal from acid solutions
… pore size distribution, SEM, TEM, ATR-IR, 29Si NMR and TGA techniques. The cation uptake performance of the materials were evaluated for single ion and mixed ions against various nitric acid conditions. The study was further extended to rate of uptake in the best performing AMPPAN …
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The Use of Functionalized Zirconocenes as Precursors to Silica-Supported Zirconocene Olefin Polymerization Catalysts
… dibromide. Combinations of solution 1H NMR, solid state CPMAS 13C NMR, and solid state CPMAS 29Si NMR spectroscopy suggested a stereoregular structure in which the metallocene units have local Cs (meso) symmetry. Although only sparingly soluble, the oligomeric substance showed activity …
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Structure-property correlations in fluoroaryl functionalized inorganic-organic hybrid polymers for telecom applications
… chiefly with solution and solid state 29Si-NMR spectroscopy, respectively. Particularly for polycondensates incorporating species based on more than one precursor silane, the spectra showed a high degree of complexity. An additional challenge arouse from the partial loss of fluoroaryl …
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Catalytic hydrofunctionalization and small molecule reactivity at a low-valent cobalt center supported by a bis(carbene) CCC pincer ligand
… linkage to the coordinated metal. Multinuclear NMR spectroscopies, cyclic voltammetry, X-ray crystallography, and EPR spectroscopies have established the successful isolation of Co(I), Co(II), and Co(III) derivatives with this ligand platform. The diamagnetic natures of the Co(I) and Co(III) …
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Siloxane modified hybrid materials by the sol-gel process
… composition and the initial reaction conditions. 29Si NMR studies were conducted to investigate the incorporation process which led to the conclusion that the PDMS chains were being degraded by the TIP. This problem led to the synthesis of TIP endcapped PDMS which was then used as the oligomeric …
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Solid-state NMR (¹³C, ²⁷Al and ²⁹Si) study of the reaction between AlMe₃ and the silica gel surface
… surface after an excess-H2O workup. Solid-state NMR (13C, 27 Al and 29Si) have been used to elucidate the structures of moieties generated on the silica gel surface at each of the stages listed above. Solid-state 13C NMR showed that Al(Me)n is the major type of moieties generated on the surface …