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Showing 1 to 20 of 45 for “"Sulfonation"”.
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Characterization of polymeric membranes: sulfonated polysulfones
… 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0 degree of sulfonation is described. The degree of sulfonation (D.S.) was maintained during the membrane fabrication process as evidenced by IR analysis. The effect of the degree of sulfonation and the counter ion, namely Na and K, on the properties of the …
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Synthesis and Characterization of Sulfonated Poly(arylene ether sulfone)s for Membrane Separations
… degradation, providing a polymer with controlled sulfonation through controlling hydroquinone content. It also avoided the disadvantages noted previously in polymers with post-sulfonated biphenol units. Initial experiments focused on determining sulfonation conditions to confirm quantitative …
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Synthesis and Characterization of Sulfonated Polyimides as Proton Exchange Membranes for Fuel Cells
… charged into the reaction flask. The levels of sulfonation in the polymer backbones were controlled by varying the mole ratio of sulfonated diamine to unsulfonated diamine. For the six-membered ring polyimides, phenolic solvents, e.g. m-cresol, have been used. In general, …
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Membranen aus [(A)n(B)m]x-Multiblockcopolymeren für den Einsatz in der Direkt-Methanol-Brennstoffzelle (DMFC)
… copolymers of (AB)n-type with various degrees of sulfonation have been prepared for use in direct methanol fuel cells.
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Structure-Property Relationships in the Design of High Performance Membranes for Water Desalination, Specifically Reverse Osmosis, Using Sulfonated Poly(Arylene Ether Sulfone)s
… sulfone) derivatives with differing amounts of sulfonation and with the ions placed at different structural positions. Previously, such materials were tested as potential high performance fuel cell membranes, but they are also of interest as potential high performance water desalination …
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Synthesis and Characterization of Hydrophobic-Hydrophilic Multiblock Copolymers for Proton Exchange Membrane and Segmented Copolymer Precursors for Reverse Osmosis Applications
… to their affordability, high Tg, and the ease of sulfonation. Proton exchange membrane fuels cells (PEMFCs) are one of the primary alternate source of energy. A Proton exchange membrane (PEM) is one of the key component in a PEMFC and it needs to have good proton conductivity under partially …
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Molecular and biochemical characterization of steroid sulfotransferases from Brassica napus and Arabidopsis thaliana
… Brassica napus . Recombinant BNST3 catalyzes the sulfonation of brassinosteroids and of mammalian estrogenic steroids. The enzyme is stereospecific for 24-epibrassinosteroids, with a substrate preference for 24-epicathasterone, a metabolic precursor of 24-epibrassinolide. The bean second internode …
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Synthesis, Characterization and Structure - Property Relationships of Post - sulfonated Poly(arylene ether sulfone) Membranes for Water Desalination
… properties of the membranes. Selective post sulfonation of poly(arylene ether sulfone) in mild conditions was also found to be an effective way to strategically place the sulfonate ions along the backbone of the polymer chain without the need to synthesize a new monomer. Hydroquinone based, …
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Influence of solution ionic strength on aggregation of novel water soluble phosphines and two phase catalysis
… from low yield and uncertainty of the site of sulfonation. Introduction of α-ω diphenylalkyl group into a chelating phosphine via LiP[C₆H₄(CH₂)ₓC₆H₅]₂ results in a new class of chiral chelating phosphines which can be easily sulfonated. This highly efficient, well defined sulfonation method …
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Chemical and Physical Modifications of Semicrystalline Gels to Achieve Controlled Heterogeneity
… is extensively investigated. First, the blocky sulfonation of PEEK was explored to prepare blocky copolymers (SPEEK) with densely sulfonated domains and unfunctionalized, crystallizable domains. Compared to random SPEEK ionomers at similar ion content, blocky SPEEK exhibited enhanced …
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The Effect of Ionomer Architecture on the Morphology in Gel State Functionalized Sulfonated Syndiotactic Polystyrene
… of samples were prepared at comparable levels of sulfonation. Thermal analysis of these two systems proved that the blocky functionalized copolymers provided superior properties with regard to the speed and total amount of the crystalline component of sulfonated syndiotactic polystyrene. Above 3% …
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Studies on the preparation and characterization of novel water-soluble catalysts
… in a supported aqueous phase catalyst. Direct sulfonation of 1,2-bis(diphenylphosphino)ethane (DPPE) has yielded 1,2-(bis[di-m-sodiumsulfonato]phenylphosphino)ethane (DPPETS), a new water soluble ligand that has been characterized and used in the synthesis of several new complexes with …
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From conventional to microphotochemistry: A study of phthalimide and phthalonitrile derivatives
… to water soluble derivatives by selective sulfonation and one such derivative was screened as a potential cell-imaging agent.
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Modification of Biopolymers Using Palladium Oxidative Addition Complexes
… Biaryl Monophosphine Ligands by Regioselective Sulfonation Amphiphilic ligands are valued for their ability to facilitate organometallic reactions in the presence of water. The regioselective sulfonation of a series of commercially available biaryl monophosphines to generate amphiphilic ligands …
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Synthesis and Characterization of Linear and Crosslinked Mono-Sulfonated Poly(arylene ether sulfone)s for Reverse Osmosis Applications
… controlled electrophilic aromatic sulfonation of 4,4'-dichlorodiphenylsulfone (DCDPS). HPLC-UV revealed complete isolation of ms-DCDPS free of by-products after the 1st recrystallization and 1H NMR analysis confirmed the structure. A standard calibration curve was developed to …
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Control of selectivity in palladium-catalysed cross-coupling reactions using a sulfonated phosphine ligand
… chiral molecule due to its desymmetrisation upon sulfonation. Resolution of the two enantiomers was achieved initially by preparative supercritical fluid chromatography in collaboration with AstraZeneca, and later by chemical resolution using a chiral auxiliary, work described in this thesis. The …
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Chemical Sensing of N-Nitrosodimethylamine and Methane
… in inser-tion polymerization was then examined. Sulfonation and nitration of the parent polymer I-AntN were also conducted and the product analyzed. Attempts at copolymerization of AntN with CO were also described.
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Fluorous- Phase Synthesis of Heparan Sulfate Disaccharides & Low-Molecular Weight Additives for Enhancing the Performance of Lithium-Ion Batteries.
… unmasking of hydroxyls or amines for subsequent sulfonation. A practical challenge of this approach is the need to carry highly polar intermediates through multiple synthetic steps. This was addressed by installing a perfluoroalkyl (fluorous) tag on the reducing end of the orthogonally protected …
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The synthesis and fluorescence properties of some substiuted naphthalimides
… containing polar terminal groups and by sulfonation on the naphthalene ring. The sulfonated compounds exhibit quite good watersolubility and the others also show some improvement. Chloroacetyl and maleimido functions have been introduced into naphthalimides as reactive groups for …
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