Ytterbium triflate hydrate catalyzed Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds

Catalyzed by ytterbium(Ⅲ) triflate hydrate [Yb(OTf)3.xH2O], the Michael addition and cycloeondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran derivatives, respectively were studied.     

Toughening effect of ethylene‐vinyl acetate rubber on nylon 1010 compatibilized by maleated ethylene‐vinyl acetate copolymers

The toughening effect of ethylene‐vinyl acetate rubbers (EVM) with maleated ethylene‐vinyl acetate copolymers (EVA‐g‐MAH) on the nylon 1010 was investigated. The addition of 5 phr (per hundred nylon 1010) EVM increased the elongation at break of nylon 1010 to a great extent. The notched Izod impact strength of nylon/EVM blends increased with increasing EVM content. Scanning electron microscope showed that the EVM particle size was around 0.5 μm when the EVM content was 5 phr and increased with increasing EVM content. After the addition of EVA‐g‐MAH to nylon/EVM (100/20) blend, the average diameter of EVM particles decreased from more than 1 μm to 0.5–0.6 μm. EVA‐g‐MAH could improve the adhesion between nylon 1010 and EVM. A sharp brittle‐ductile transition (BDT) was observed when the interparticle distance was about 0.2 μm, independent of the addition of EVA‐g‐MAH. The notched Izod impact strength of nylon/EVM blends at low temperatures was measured and the BDT shifted toward low temperatures with increasing EVM or EVA‐g‐MAH content. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 434–444, 2009     

Synthesis and optoelectronic properties of alternating benzofuran/terfluorene copolymer with stable blue emission

The solution processable alternating benzofuran/terfluorene copolymer bearing side oxadiazole groups ( PBF‐OXD ) was synthesized and its optoelectronic properties and color stability were investigated. Electron‐deficient and stereohindered oxadiazole units were used as pendent groups to compensate for the poor electron‐transporting ability of a p‐type polymer backbone, to depress the intermolecular π‐stacking, and to improve solubility while retaining polymer blue emission. PBF‐OXD showed a glass transition at 135 °C and an onset decomposition temperature of ～345 °C. A simple EL device, with the configuration of ITO/PEDOT:PSS/ PBF‐OXD /Ba/Al, displayed a stable blue emission (λ_max = 434 nm), good color purity (full width half‐maximum = 59 nm), maximum brightness of 1400 cd/m², and a maximum luminance efficiency of 0.95 cd/A. The PL and EL spectra changed slightly on annealing and on increasing the applied voltage. These results show that the as‐synthesized copolymer PBF‐OXD had integrated respective functions of its different building blocks and exhibited good thermal and color stability with improved EL performance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5488–5497, 2009     

Stokes问题各向异性网格Q2-P1混合元超收敛分析

讨论Stokes问题在各向异性冈格下的Q2-P1混合有限元方法，利用积分恒等式技巧得到了与传统方法相同的超逼近性质，同时基于插值后处理的技巧，构造了速度和压力的一对插值后处理算子，并且前者具有备向异性特征，从而导出了整体超收敛结果．     

Sur quelques propriétés de la représentation conforme des domaines multiplement connexes,en relation avec le théorème des fentes parallèles

Sans résumé