No abstract

Porous silica nanofibers containing catalytic silver nanoparticles have been synthesized by a new method that combines sol−gel chemistry and electrospinning technique. Tetraethyl orthosilicate (TEOS), poly[3-(trimethoxysily)propyl methacrylate] (PMCM), and silver nitrate (AgNO3) were used as precursors for the production of silica−PMCM hybrid fibers containing AgNO3. Calcination of the hybrid fibers at high temperatures results in porous silica fibers because of thermal decomposition of PMCM polymer and in conversion of AgNO3 to silver nanoparticles. The color of the fiber mats changed from white to dark golden yellow due to the surface plasma resonance of the silver nanoparticles embedded in the fibers. The size and density of the silver particles in the silica fibers could be tuned by varying the size of the fibers, amount of AgNO3 introduced, and the thermal treatment conditions. The silica fibers containing silver particles were characterized with environmental scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV−vis spectroscopy, and thermogravimetric analysis. The catalytic activity of the silver containing fiber mats was assessed by a reduction reaction of methylene blue dye.

Fe 3 O 4 microsphere is a good candidate as support for catalyst because of its unique magnetic property and large surface area. Coating Fe 3 O 4 microspheres with other materials can protect them from being dissolved in acid solution or add functional groups on their surface to adsorb catalyst. In this paper, a carbon layer was coated onto Fe 3 O 4 microspheres by hydrothermal treatment using polyethylene glycol as the connecting agents between glucose and Fe 3 O 4 spheres. Through tuning the added amounts of reactants, the thickness of the carbon layer could be well-controlled. Because of the abundant reductive groups on the surface of carbon layer, noble metal ions could be easily adsorbed and in situ reduced to nanoparticles (6-12 nm). The prepared catalyst not only had unique antiacid and magnetic properties, but also exhibited a higher catalytic activity toward the reduction of methyl orange than commercially used Pd/C catalyst.

New bisphenol monomers, (3‐methyl)phenylhydroquinone and (3‐trifluoromethyl)phenylhydroquinone, were prepared in a two‐step synthesis. A series of poly(aryl ether ketone)s were derived from these bisphenols via a nucleophilic aromatic substitution polycondensation with various bisfluoro compounds. The polycondensation proceeded quantitatively in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the polymers with inherent viscosities of 0.63–0.91 dL/g. The fluorinated polymers showed lower glass‐transition temperatures and higher thermal‐decomposition temperatures than the corresponding nonfluorinated polymers. The solubility of the polymers was improved by the introduction of bulky pendant groups. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 86.4–102.0 MPa, Young's moduli of 2.28–3.03 GPa, and elongations at break of 14–42%. All the polymers had low dielectric constants of 2.70–2.83 at 1 MHz. Compared with the methylated polymers, the trifluoromethylated polymers exhibited lower water sorption, which was attributed to the stronger hydrophobicity of the fluorine‐containing groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3392–3398, 2002