Complex aggregates of spherical colloids via modified micromolding in capillaries

This paper describes a simple approach to fabricate aggregates composed of monodispersed silica microspheres by modified micromolding in capillaries (MIMIC). Two different kinds of contact modes, namely, conformal contact and non-conformal contact, between the poly(dimethylsiloxane) (PDMS) mold and the underlying prepatterned substrate, can be controlled during the micromolding, which result in the formation of different aggregates under the influence of template confinement and capillary forces. These aggregates, including woodpile structure, discoid, conoid and rectangular clusters, possess well-controlled sizes and orientation. The possible mechanisms for the formation of different aggregates are discussed in detail.

Synthesis, structure and reactive mechanism of intermetallic W3Mg

Assisted by mechanical alloying and high-pressure technique, a new W3Mg intermetallic was formed. W3Mg amorphous mixture was obtained by mechanically alloying the pure metal powder mixtures at designated composition for 20 h. A new compound was found after the Subsequent high pressure and high temperature treatment. W3Mg intermetallic was identified as a tetragonal structure and the lattice parameter was a = 0.7880 nm, c = 0.7070 nm. The synthesis mechanism is also discussed in this paper.

几种CPP树脂的pVT特性

利用 PVT- 100分析仪对几种不同牌号的流延聚丙烯 (CPP)进行了 p VT特性测量 ,得到了比容随温度和压力变化的关系。通过公式法计算出热膨胀系数 α和等温压缩系数 β与温度和压力的依赖关系 ,并与由 Tait方程计算出的 α和 β结果进行了比较。另外从比容随温度和压力变化的关系图得到了各种牌号 CPP熔融温度 Tm 与压力的关系。最后通过高温凝胶渗透色谱 GPC法测量实验前后样品的分子量表明 CPP在 p VT特性测试过程中有部分降解

UV-VUV excited luminescence of SrBPO5 : Sm phosphor prepared in air

The high-resolution luminescent spectrum of divalent samarium excited by 355 nm UV light at 77 K, the VUV excitation spectra, the VUV excited emission spectra and EXAFS at Sm-L-3 edge were reported for samarium doped strontium borophosphate, SrBPO5:Sm prepared by solid state reaction in air at high temperature. The high-resolution luminescent spectrum showed that the divalent samarium ions occupied the C-2upsilon lattice sites. The VUV excitation spectra indicated that the sample exhibited absorption bands with the maxima at 129 and 148 nm, respectively. The performance of EXAFS at Sm-L3 absorption edge suggested that the samarium ions were nine-coordinated and the mean distances of bond Sm-O were 2.38 Angstrom.

Hydrothermal synthesis and crystal structure of a novel compound: [Ni(phen)(3)](2)[(SiMo10V2O40)-O-IV((VO)-O-IV)2]center dot 2H(2)O

A novel compound [Ni(phen)(3)](2)[(SiMo10V1/2O40)-O-V((VO)-O-IV)(2)] . 2H(2)O has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the triclinic, system, space group P-1, a = 12.378(4) Angstrom, b = 14.148(5) Angstrom, c = 14.316(2) Angstrom, alpha = 105.91(2)degrees, beta = 95.31(2)degrees, gamma = 96.89(3)degrees, V = 2373.0(12) Angstrom(3), Z = 1, (lambdaMo(Kalpha)) = 0.71073 Angstrom, R1 (wR2) = 0.0869(0.2174). Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range of 1.51 < theta < 22.50degrees using the omega-scan technique. Empirical absorption correction (psi scan) was applied. The structure was solved by the direct method and refined by the Full-matrix least-squares on F-2 using the SHELXL-97 software. X-ray crystallographic study showed that the title compound contained a bi-capped alpha-Kegin-type [(SiMo10V2O40)-O-IV((VO)-O-IV)(2)](4-) polyoxoanion.

Study on the transesterification of poly(beta-hydroxybutyrate) and poly(epsilon-caprolactone)

The transesterification of poly(beta-hydroxybutyrate) (PHB) and poly(epsilon-caprolactone) (PCL) was carried out by using stannous octoate as catalyzer in liquid phase. The effects of reaction conditions on the transesterification, including reaction temperature, reaction time and catalyzer content, were investigated. The sequence distribution, crystallization behavior and thermal stability of PHB-co-PCL copolyesters were studied by C-13-NMR, FTIR, DSC, WAXD and TGA. The results showed that the transesterification of PHB with PCL was confirmed to produce a block copolymer, and enhancing reaction temperature and increasing reaction time were advantageous to the transesterification. With the increase in PCL content in the block copolymer, the crystallization behavior of PHB-co-PCL copolyesters changed evidently. On the other hand, the introduction of PCL segment into PHB chains did not change its crystalline structure; moreover, thermal stability of PHB-co-PCL copolyesters was a little improved in air, comparing with that of pure PHB.

聚β-羟基丁酸酯和聚ε-己内酯的酯交换反应

以辛酸亚锡为催化剂 ,研究了聚 β 羟基丁酸酯 (PHB)与聚ε 己内酯 (PCL)在液相条件下的酯交换反应 .讨论了反应时间 ,反应温度和催化剂浓度对酯交换反应的影响 .采用1 3C NMR ,FTIR ,DSC ,WAXD和TGA等方法对PHB和PCL共聚酯 (PHB co PCL)的结构进行了表征 ,并对其结晶行为、晶体结构和热稳定性进行了研究 .结果表明 ,通过酯交换反应 ,所得到的共聚酯为嵌段共聚物 .提高反应温度和延长反应时间有利于酯交换反应的发生 .随着酯交换量的增加 ,PHB co PCL的结晶行为发生很大的变化 .但是 ,PHB co PCL晶体结构并没有因为PCL链段的引入而发生变化 ,而且它的热稳定性在空气气氛中略有提高

溶胶对辐射交联高密度聚乙烯的熔融行为及非等温结晶动力学的影响

通过差示扫描热分析对辐射交联高密度聚乙烯的纯溶胶、纯凝胶及溶凝胶混合体系的熔融和非等温结晶动力学行为进行了研究。结果表明，在相同辐射剂量下，含有溶胶的试样的熔点及结晶峰温均高于纯凝胶试样。含有溶胶的试样，其Avrami指数基本上高于相应的纯凝胶的Avrami指数，且前者的数值更接近原始高密度聚乙烯。因此，溶胶的存在与否，对辐射交联高密度聚乙烯的熔融行为及非等温结晶动力学有很大的影响。

有机化合物立体异构体自动解析专家系统的研究—立体中心的确认

提出了一种查找化合物中立体中心的算法 ,通过该算法可以找到和确认化合物中由于不对称碳和碳碳双键等产生的所有的立体中心。

Formation and characterization of heteropolyacid/polycation multilayer films on gold electrode

Ultrathin multilayer films of a polybasic lanthanide heteropoly tungstate-molybdate complex and a cationic polymer of quaternized poly(4-vinylpyridine) partially complexed with osmium bis(2,2'-bipyridine) have been fabricated on a gold electrode precoated with a cysteamine self-assembled monolayer. The multilayer films have been characterized by optical spectroscopy, small-angle X-ray diffraction, and electrochemical methods (cyclic voltammetry and electrochemical impedance). Especially, the electrochemical impedance spectroscopy is developed to monitor the layer deposition processes. It provides important information such as double-layer capacitance and charge-transfer resistance. All obtained results reveal regular film growth with each layer adsorption. (C) 2001 The Electrochemical Society.

Preparation of a composite film electrode containing 12-tungstosilicic acid and its electrocatalytic reduction for nitrite

A novel organic-inorganic composite film was formed by attaching Keegin-type heteropolyanion, SiW12O404- (devoted briefly as SiW12), on a glassy carbon electrode derivatized by 4-aminophenyl group. The composite film has an ionic bonding character between SiW12 and the surface amino group, which greatly improves the Blm stability and exhibits a more reversible electrochemical behavior. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of nitrite. Possible mechanism was provided for the reaction of nitrite with SiW12O404-/aminophenyl composite film.

聚酰胺、聚酯类工程塑料的增韧剂—官能化乙丙橡胶的研制

用2.5-二甲基-2.5-二特丁基过氧基己烷为引发剂,甲基丙烯酸环氧丙酯(GMA)、马来酸酐(MAH)和丙烯酸(AA)为接枝单体,对二元乙丙橡胶(EPR)和三元乙丙橡胶(EPDM)进行熔融接枝,接枝产物用富里叶红外光谱(FTIR)、~(13)C核磁共振波谱(NMR)等,进行了表征并用化学滴定方法对接枝率进行了测定。实验结果表明影响接枝率和凝胶含量的主要因素为乙丙橡胶的化学结构、引发剂和单体的用量、反应时间及温度等。

The crystal structure and drawing-induced polymorphism in poly(aryl ether ketone)s .2. Poly(ether ether ketone ketone), PEEKK

The crystal structure, morphology and polymorphism induced by uniaxial drawing of poly(ether ether ketone ketone) [PEEKK] have been studied by transmission electron microscopy (TEM), electron diffraction (ED) and wide angle X-ray diffraction (WAXD). On the basis of WAXD and ED patterns,the crystal structure of unoriented PEEKK is determined to have two-chain orthorhombic packing with unit cell parameters of a 0.772 nm, b = 0.600 nm, c = 1.004 nm (form I), A stress-induced crystal modification (form II) is identified and found to possess a two-chain orthorhombic lattice with unit cell dimensions of a = 0.461 nm, b = 1.074 nm, c = 1.080 nm. The 7.5% increase in c-axis dimension for form II is attributed to an overextended chain conformation, arising from extensional deformation during uniaxial drawing and fixed ''in-situ'' through strain-induced crystallization. The average ether-ketone bridge bond angles in form II crystal are determined to be 148.9 degrees by using standard bond lengths. The crystal morphology of PEEKK bears a great similarity to that of PEEK. The crystals grow in the form of spherulites and have the b-axis of unit cell radial. The effects of draw rate on strain-induced crystallization and induction of form II structure are also discussed.

A new solid-state electrolyte: Rubbery 'polymer-in-salt' containing LiN(CF3SO2)(2)

A new class of rubbery 'polymer-in-salt' electrolytes for application in solid-state lithium batteries has been explored by differential scanning calorimetry and a.c. impedance analysis. Simple phase diagrams of LiN(CF3SO2)(2)+LiClO4 and LiC(CF3SO2)(3)+LiN(CF3SO2)(2) have been drawn, which are very important to determine polymer-in-salt electrolyte materials. The conductivities obtained by a.c. impedance measurement are smaller for the electrolyte that contains acetate LiOAc salt than for the electrolyte without this salt.

STRUCTURE AND PROPERTIES OF SELF-DOPED POLYANILINE

Sulfonated polyaniline(SPAn) with different sulfonation degree(SD) was prepared, its structure was studied by spectroelectrochemical method, some of its special properties were given.