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Recently, silver nanoparticles(NPs)-based photocatalysts have attracted more attention due to their enhanced visible light photocatalytic activity. In this work, a new Ag@Ag3PO4photocatalyst have been prepared by precipitation replacement and reduction methods. The products were characterized by XRD and SEM. The photocatalytic activities was evaluated using 2-naphthol and methyl orange degradations under visible light irradiation (λ > 400 nm). The degradation rates of 2-naphthol and methyl orange with initial concentration of 15 mg•L-1reached 80% and 99% respectively by using 0.6 g•L-1Ag@Ag3PO4. The photocatalytic mechanism was discussed.

The graphene/poly(vinyl alcohol) nancomposites with enhanced filler-matrix interfacial interaction were fabricated via water-blending partially reduced graphene oxide (PRGO) and poly(vinyl alcohol)(PVA). The nanocomposites were characterized by X-ray Diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), Scanning Electron Microscopy(SEM), thermogravimetry(TG). The results showed that the graphene nanosheets were homogeniously dispersed in the PVA matrix and enhanced interfacial adhesion was greatly enhanced due to new covalent linkage and hydrogen-bonding between graphene and PVA backbone. The mechanical and thermal properties of the nanocomposites were significantly improved at low graphene loadings. An 116% increase in tensile strength and a 19°C improvement of onset thermal degradation temperature were achieved by the addition of only 0.8 wt% graphene.

The molecular design for inherently flame-retardant poly(lactic acid) (IFR-PLA) was outlined and achieved by chemically incorporating an effective organophophorus-type flame retardant (FR) into the PLA backbone via the chain extension of the dihydroxyl-terminated prepolymer with 1, 6-hexamethylene diisocyanate (HDI). The structure of IFR-PLA was characterized by 1 H- and 31 P-nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. IFR-PLA was further blended with the commercial PLA to prepare flame retardant PLA blends (PLA-FR blend). The relevant properties of IFR-PLA and PLA-FR blends were evaluated by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), limiting oxygen index (LOI) measurements and UL-94 tests. The thermal analysis revealed that the char yield of IFR-PLA and PLA-FR blend above 400 °C was greatly enhanced compared to that of pure PLA. The LOI value was significantly improved from 19 for pure PLA to 29 when 1 wt% of phosphorus content was introduced and all IFR-PLA samples achieved V-0 rating in the UL-94 tests. PLA-FR blends had an LOI value of 25–26 and UL-94 V-2 rating at 20 wt% of IFR-PLA content. The tensile strength of all the FR PLA systems was ca. 60 MPa. The method used in this study provided a novel route to permanently flame retard PLA.

Graphene has attracted much interest in recent years due to its unique and outstanding properties. Dif- ferent routes to prepare graphene have been developed and achieved. Preparation methods of graphene used in re- cent years are intensively introduced, including micromechanical cleavage, chemical vapor deposition, liquid/gas- phase-based exfoliation of graphite, epitaxial growth on an insulator, chemical reduction of exfoliated graphene oxide, etc. And their advantages and shortcomings are further discussed in detail. The preparations of graphene are also prospected.

Micron-size functional crosslinked poly(methyl methacrylate) (PMMA) particles with narrow size distribution in the range of 1∼5 µm were prepared by dispersion copolymerization in polar media with poly(N-vinylpyrrolidone)(PVP) as steric stabilizer, 2,2′-azobisisobutyronitrile(AIBN) as initiator and ethylene glycol dimethylacrylate (EGDMA) as crosslinking agent. The effects of functional comonomer acrylic acid (AA) concentration, contents in AIBN, EGDMA and PVP, media polarity as well as reaction temperature on the particle size and size distribution were investigated. Particle size initially increased, and then decreased with increasing AA concentration in the range of 0.7∼3.5 mol l−1, having a maximum of 5.01 µm at the concentration of 2.1 mol l−1, while size distribution became broader. This was regarded as the result of different roles of PAA in the process. Particle size increased with decreasing media polarity and stabilizer concentration, and with increasing initiator concentration and reaction temperature. The resulting particle shapes were observed by transmission electron microscopy and the presence of carboxyl groups on the surface of the particles was confirmed by Fourier-transform infrared spectroscopy. Copyright © 2003 Society of Chemical Industry