Composite poly(ethylene carbonate) electrolytes with electrospun silica nanofibers

We prepared a ternary composite polymer electrolyte from poly(ethylene carbonate) (PEC), lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and non‐calcined silica nanofibers (SNFs) having 3 average diameters (300, 700, and 1000 nm). The SNF composite electrolytes were obtained as homogeneous, self‐standing membranes. The ionic conductivity of PEC/LiTFSI 100 mol% was increased by the addition of SNFs, and the thinner SNFs with average diameter 300 nm were most effective in improving the conductivity. The conductivity was of the order of 10⁻⁴ S/cm at 60°C. The lithium transference number of the SNF₃₀₀ composite was greater than 0.7. Stress‐strain curves of the composites indicated significant increases in Young's modulus and maximum stress for the PEC electrolytes. The 5% weight‐loss temperature of the composites also improved with the addition of SNF.     

Kinetics and mechanistic aspects on electron‐transfer process for permanganate oxidation of poly(ethylene glycol) in aqueous acidic solutions in the presence and absence of Ru(III) catalyst

The kinetics and mechanism of oxidation of poly(ethylene glycol) (PEG) by the permanganate ion as a multiequivalent oxidant in aqueous perchlorate solutions at an ionic strength of 2.0 mol dm⁻³ has been investigated spectrophotometrically. The reaction kinetics was found to be of complex in nature. The pseudo–first‐order plots showed curves of inverted S‐shape, consisting of two distinct stages throughout the entire course of reaction. The first stage was relatively slow, followed by a fast reaction rate at longer time periods. The first‐order dependence in [MnO₄⁻], fractional first‐order dependence in [H⁺], and fractional first‐order kinetics in the PEG concentration for the first stage have been revealed in the absence of the Ru(III) catalyst. The influence of the Ru(III) catalyst on the oxidation kinetics has been examined. The oxidation was found to be catalyzed by the added Ru(III) catalyst. The First‐order dependence on the catalyst and zero order with respect to the oxidant concentrations have been observed. The kinetic parameters have been evaluated, and a tentative reaction mechanism consistent with the kinetic results is suggested and discussed.     

Biocompatibility evaluation of self‐assembled micelles prepared from poly(lactide‐co‐glycolide)‐poly(ethylene glycol) diblock copolymers

In this work, a series of PLGA‐PEG diblock copolymers were synthesized by ring‐opening polymerization of L‐lactide and glycolide using mPEG as macroinitiator and stannous octoate as catalyst. Spherical micelles were obtained from the various copolymers by using co‐solvent evaporation method. The biocompatibility of micelles was evaluated with the aim of assessing their potential in the development of drug delivery systems. Various aspects of biocompatibility were considered, including MTT assay, agar diffusion test, release of cytokines, hemolytic test, dynamic clotting time, protein adsorption in vitro, and zebrafish embryonic compatibility in vivo. The combined results revealed that the micelles present good cytocompatibility and hemocompatibility in vitro. Moreover, the cumulative effects of micelles throughout embryos developing stages have no toxicity in vivo. It is thus concluded that micelles prepared from PLGA‐PEG copolymers present good biocompatibility as potential drug carrier.     

简单方法制备与表征新颖复合凝胶及表面微结构——由科研成果转化的化学综合实验

材料表面的微结构会赋予材料独特的性能,水凝胶在生物医学领域有广泛的应用前景。采用紫外光刻蚀法创新性地实现了复合凝胶的制备和凝胶表面图案化微结构的构筑一步完成;通过原子力显微镜和光学显微镜的表征,复合凝胶聚N-异丙基丙烯酰胺/聚乙二醇二丙烯酸酯兼具了温敏性能与图案化微结构的新颖性能结构特征。本实验有助于培养学生的创新意识,激发学生的学习兴趣以及未来从事科研的兴趣。     

碳酸乙烯酯选择加氢合成甲醇与乙二醇高效稳定Cu/SiO2催化剂研究

CO2作为重要的碳氧资源, 具有来源丰富、价格低廉、安全等突出优点. 近年来, 由于蕴含的巨大利用潜力,CO2间接利用制备基础化学品、能源燃料对于可持续制备大宗化工品中具有重要研究意义, 日益受到研究者和工业界的广泛重视.甲醇与乙二醇是化学工业中的两种重要大宗原料. 甲醇不仅是重要的有机化工原料、清洁环保的液体燃料, 同时也是氢气和能量储存的良好载体. 乙二醇作为一种重要的有机化工原料, 在聚酯等领域具有广泛应用.CO2经碳酸乙烯酯氢解制备甲醇/乙二醇是典型的原子经济反应, 对资源、能源和环境的可持续发展具有重要意义. 需要指出的是,CO2与环氧乙烷环加成制备碳酸乙烯酯已具备成熟的工业化技术. 因此, 该路线研究重点在于发展碳酸乙烯酯选择加氢联产甲醇和乙二醇高效稳定的催化体系. 近年来, 铜基多相催化剂催化碳酸乙烯酯加氢联产甲醇乙二醇得到了广泛重视. 由于铜基催化剂存在活性较低、高温易失活等问题, 开发高效且具有良好稳定性的铜基催化剂是目前碳酸乙烯酯加氢研究重点.本文针对碳酸乙烯酯选择氢解合成甲醇乙二醇新型铜基催化体系构建和构效关系研究, 采用硅溶胶蒸氨法制备高分散 Cu/SiO2过程中引入多羟基β-环糊精修饰催化剂前驱体的合成策略, 并通过惰性气体中煅烧后的积碳有效抑制活性铜物种的团聚, 获得了β-环糊精改性的 Cu/SiO2催化剂. 通过 N2吸脱附、XRD、N2O 滴定、H2-TPR、TEM 和 XPS 等系统表征,发现β-环糊精可有效调控催化剂结构和表面不同价态活性铜物种分布. 碳酸乙烯酯加氢性能评价结果表明引入适量β-环糊精的 5β-25%Cu/SiO2具有较优催化活性, 乙二醇选择性 98.8% 和甲醇选择性 71.6%, 且相应的催化活性可达 1178 mgEC gcat-1h-1. 高活性的原因很可能归因于不同价态 Cu0与 Cu+物种协同催化作用及适宜的 Cu+/(Cu0+Cu+) 比例. 结合密度泛函理论模拟计算, 我们提出了 Cu0促进氢气解离、Cu+吸附活化碳酸乙烯酯分子中酯羰基的反应机理. 催化剂重复使用和表征结果表明, 5β-25%Cu/SiO2具有良好的稳定性, 使用前后铜粒子大小和铜物种分布几乎未发生明显变化. 本文为解决铜基催化剂高温易烧结等难题提供了简单有效的活性铜物种稳定化方法, 并为CO2经碳酸乙烯酯绿色合成甲醇、乙二醇高效稳定铜基催化新体系的构筑提供了有益借鉴.     

Preparation,characterization, DFT calculations and ethylene oligomerization studies of iron(II) complexes bearing 2-(1H-benzimidazol-2-yl)-phenol derivatives

Five 2-(1H-benzimidazol-2-yl)-phenol derivatives including 1H (HL₁), 5-chloro-(HL₂), 5-methyl-(HL₃), 5,6-dichloro-(HL₄), and 5,6-dimethyl-(HL₅) were synthesized by the reaction of their corresponding benzene-1,2-diamine precursors and 2-hydroxybenzaldehyde which subsequently was employed in complexation with Fe(II) to prepare complexes C1–C5, respectively. Indeed, in all complexes, the ligands were coordinated as bidentate, via the C=N nitrogen and hydroxy oxygen atom of benzimidazole moiety and phenol ring, respectively. The compounds were characterized by FTIR, UV–vis, ¹H- and ¹³C-NMR spectropscopy, ICP, and elemental analysis (C, H, and N). The purity of these compounds was determined by melting point (m.p )and TLC. The synthesized ligands and complexes were geometrically optimized by Gaussian09 software at B3LYP/TZVP level of theory and satisfactory theoretical–experimental agreement was achieved for analysis of IR data of the compounds. Catalytic behavior of the iron(II) complexes was investigated for ethylene reactivity. On activation with diethylaluminum chloride (Et₂AlCl), iron(II) complex (C4) showed the highest activity (1686 kg oligomers.mol^?1(Fe).h^?1) for ethylene oligomerization when it contains chlorine substituents and exhibits good selectivity for linear 1-butene. The steric and electronic effects of ligands were investigated in detail on the influence of their catalytic activities.     

磷酸氢二钾催化多组分一锅法反应合成1,4-二氢吡喃并[2,3-c]吡唑衍生物

绿色、简便、高效的催化四组分反应合成吡喃并[2,3-c]吡唑类杂环化合物是当今有机化学领域的研究热点。 本文发展了在水与聚乙二醇(PEG-200)的混合液中,廉价易得的磷酸氢二钾(K₂HPO₄·3H₂O)催化乙酰乙酸乙酯、水合肼、芳香醛和丙二腈的多组分“一锅法”反应,合成一系列1,4-二氢吡喃并[2,3-c]吡唑-5-腈衍生物,产率为88%~98%。 该方法避免了使用复杂昂贵的催化剂和繁琐的纯化过程。     

注射用生物可降解胰岛素纳米微球的制备

共聚物;药剂释放体系;注射用生物可降解胰岛素纳米微球的制备     

Effect of the comonomer content on the mechanical parameters and microhardness values in poly(ethylene‐co‐1‐octadecene) synthesized by a metallocene catalyst

Stress–strain and microhardness measurements were carried out on a series of copolymers of ethylene and 1‐octadecene with different comonomer contents in the corresponding homopolymer of ethylene, synthesized with a metallocene catalyst. The different mechanical properties, deduced from the stress–strain curves (Young's modulus, yield stress, deformation at break, and energy to break) are interpreted in terms of the crystallinity and molecular weight of the samples because these two characteristics show considerable variations with the comonomer content. The microhardness values are explained in terms of these properties, and they are also correlated with Young's moduli and yield stresses deduced from the stress–strain curves. Linear relations are found between microhardness and yield stress and between the logarithm of the microhardness and the logarithm of the elastic modulus. The properties deduced from these lines are compared with literature values. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 277–285, 2001     

Synthesis of an amphiphilic styrenic block copolymer: Polycondensation of dichloromethane and low molecular weight poly(ethylene glycol) in the presence of hydroxypropylated polystyrene‐block‐polybutadiene

An amphiphilic styrenic block copolymer, polystyrene‐block‐polybutadiene‐block‐poly[oxymethylene‐alt‐oligo(oxyethylene)] (PS‐b‐PB‐b‐POME), was synthesized through a polycondensation reaction of low molecular weight poly(ethylene glycol) and dichloromethane in the presence of hydroxypropylated polystyrene‐block‐polybutadiene (PS‐b‐PB‐OH) used as a monofunctional chain‐capping reagent. PS‐b‐PB‐OH was in turn prepared via an anionic synthesis of PS‐b‐PB followed by oxetane capping and methanol quenching. Although PS‐b‐PB‐OH has insignificant hydrophilicity, PS‐b‐PB‐b‐POME containing both the hydrophobic PS‐b‐PB segment and the hydrophilic POME segment had an improved emulsifying capability and effectively decreased the interfacial tension between water and toluene. The hydrophile–lipophile balance value of this amphiphilic PS‐b‐PB‐b‐POME copolymer, consisting of 86 wt % of the POME segment and 14 wt % of the PS‐b‐PB segment, was 17.2. The molecular weight of the copolymer molecule was determined by gel permeation chromatography–multi‐angle laser light scattering, and the microstructure was analyzed using ¹H NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2625–2632, 2001