Reactive Polymers最新文献

A series of polyamides containing aromatic or heteroaromatic and aliphatic fragments in their repeat unit were synthesized and used as supports to immobilize a catalyst based on a [RhCl(CO)₂]₂ precursor. The polymeric materials were characterized by differential scanning spectroscopy (DSC), wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), specific surface area and porosity measurements. The catalytic properties of polyamide-supported Rh(I) catalysts were studied in hydrosilylation of vinyl-type olefins. The selectivity of this reaction towards formation of the linear adducts over the branched ones was found to be greatly influenced by the matrix supramolecular structure when compared with that in the homogeneous phase. Based on SAXS measurements, the high selectivity of the polymer-immobilized rhodium catalysts was attributed to the matrix microporous structure displaying a narrow distribution of pores mostly in the range from r = 1.0 to 3.0 nm.

Selective hydroformylation of styrene to iso-aldehyde, 2-phenylpropionaldehyde in higher than 90% yield has been achieved catalyzed by silica-supported poly-γ-aminopropylsiloxane-ruthenium-cobalt bimetallic complex catalysts (SiNH₂RuCo) in the presence of acetic acid. The $\text{Ru}\text{Co}$ mole ratio, the amount of acetic acid and total pressure greatly influenced the reaction. The catalyst was stable and could be used repeatedly without any remarkable changes in activity and selectivity.

The modification of the electrodynamic transport properties of conducting polypyrrole membranes by the use of dodecylsulfate anions during polymerization has been demonstrated. The use of small amounts of the surfactant counterion in combination with paratoluene sulfonate as the predominant anion during polymerization allows the production of conductive, mechanically stable materials with differing chemical properties. This, in turn, influences the transport characteristics and has been found to induce asymmetric transport character in the membrane.

A wide variety of chelating organic ion exchange resins and inorganic ion exchangers were tested for the removal of nickel and zinc from waste effluents from metal plating plants. Best performances were found to be exhibited by three chelating resins, sodium titanate and an active carbon impregnated with oxine. For most of these exchangers, the batch separation percentages were 99.9% or higher at pH above 5. Column experiments showed that the most effective exchanger for nickel was an inorganic ion exchanger, sodium titanate, and for zinc an aminophosphonate resin, Duolite ES 467.

Gelatin spherical microparticles were prepared by suspending a 20 wt% aqueous solution of gelatin in a 10 wt% aqueous solution of polyvinylpyrrolidone. Gelatin was used either without modification, or it was extracted with water or ammonium hydroxide. Suspending was carried out at 60°C. The particle size decreased considerably when the extracted gelatin was used, or when ammonium hydroxide was added to the suspension medium. Increasing the stirring intensity decreased the particle size and also the stability of the particles. The particles were stabilized by cooling and crosslinking with formaldehyde and separated from the suspension medium by washing with methanol. The resulting particles were dried of ethyl acetate. Five samples of the gelatin microparticles were prepared, the diameters of which varied from 0.5 to 15 μm in dry state.

Chelating resin loaded with 5-sulfosalicylic acid, Poly[N-chloranil N,N,N′,N′-tetramethylethylenediammonium di-sulfosalicylate], was obtained by an ion-exchange reaction with N,N,N′,N′-tetramethylethylenediamine-chloranil copolymer as matrix. A useful chromatographic packing is prepared by immobilizing this chelating resin on silica gel. A detail analytical characterization of this silica-immobilized sorbent was carried out and optimum and selective sorption conditions for some heavy metals under static and dynamic conditions were established. The maximum absorption capacity was found to be 3.95 μmol of metal ions per gram of the sorbent at their respective optimum pH (optimum pH values for selective metal ions are: Cd²⁺, 3.2; Cu²⁺, 4.5; Fe³⁺, 5.0; Co²⁺, 6.9). The typical flow rates of 5 ml/min for Cu²⁺, Co²⁺ and Fe³⁺, and 3 ml/min for Cd²⁺ were found suitable for selective and quantitative separations of these metals from the multicomponent mixtures of heavy metals present in the water samples. After separation of traces of metals on the sorbent and subsequent desorption with 1 M nitric acid, the metal ions were determined in the eluent by employing differential pulse anodic stripping voltammetry.