Electrocatalytic Oxidation of Formic Acid by Polyaniline-Poly （ Propylene Oxide）

Formic acid is a liquid fuel for the direct formicacid fuel cell (DFAFC), which has a high theoretical open circuit potential and is an attractive alternativefor portable power devices. In the past, the research of the electrochemical behavior of formic acid was limited to Pt, Pt/Pd or Pt/Ru. Many studies have shown that the electrocatalytic oxidation rate of formic acid on a pure Pt electrode is insufficient for DFAFC.     

Preparation of PdCo Bimetallic Hollow Nanospheres and its Electrocatalytic Activity for Oxidation of Formic Acid

The performance of the direct formic acid fuel cell (DFAFC) is considerably higher than the direct methanol fuel cell (DMFC) because of some characteristics of formic acid1. For example, formic acid is non-toxic. Formic acid has two orders of magnitude smaller crossover flux through a Nafion membrane than methanol2. In DFAFC, the concentration of formic acid can be as high as 20 mol/L, while the best concentration of methanol in DMFC is only about 2 mol/L3. Thus, the power density of …     

Electrocatalytic Activity of Platinum Particles Electrodeposited onto Poly（vinylpyridine）Films

The electrocatalytic prpertics of platinum microparticles incorporated into poly-(vinylpyridine)(PVP) films ,a conducting polymer with good conductivity and stability,were investigated for hydrogen evolution and formic acid electrooxidation in acidic media,It was found that the catalytic effects depend mainly on the size and amounts of the platinum microparticles dispersed in the polymer layer.     

Preparation, Electrochemical Behavior and Electrocatalytic Activity of a Copper Hexacyanoferrate Modified Ceramic Carbon Electrode

A copper hexacyanoferrate modified ceramic carbon electrode （CuHCF/CCE） had been prepared by two-step sol-gel technique and characterized using electrochemical methods. The resulting modified electrode showed a pair of well-defined surface waves in the potential range of 0.40 to 1.0 V with the formal potential of 0.682 V （vs. SCE） in 0.050 mol·dm^-3 HOAc-NaOAc buffer containing 0.30 mol·dm^-3 KCl. The charge transfer coefficient （a） and charge transfer rate constant （ks） for the modified electrode were calculated. The electrocatalytic activity of this modified electrode to hydrazine was also investigated, and chronoamperometry was exploited to conveniently determine the diffusion coefficient （D） of hydrazine in solution and the catalytic rate constant （kcat）. Finally, hydrazine was determined with amperometry using the resulting modified electrode. The calibration plot for hydrazine determination was linear in 3.0 × 10^-6--7.5 × 10^-4 mol·dm^-3 with the detection limit of 8.0 × 10^-7 molodm^-3. This modified electrode had some advantages over the modified film electrodes constructed by the conventional methods, such as renewable surface, good long-term stability, excellent catalytic activity and short response time to hydrazine.     

聚苯胺和聚吡咯膜电极对Fe（Ⅱ）和Sb（Ⅲ）电催化作用

Ｆｅ（Ⅱ）和Ｓｂ（Ⅲ）的氧化还原峰电流在聚苯胺（ＰＡｎ）和聚吡啶（ＰＰｙ）膜电极上比在铂丝电极上高出一倍至数倍。在膜电极上氧化峰电位与还原峰电位之差值（△Ｅｐ）也比在铂丝电极上显著减小．说明两种膜电极对Ｆｅ（Ⅱ）和Ｓｂ（Ⅲ）离子的电极反应有较好的电催化活性。在电位扫描速度较低时，两种离子在聚合物膜电极上的氧化和还原反应的催化活性相近。     

Synthesis, Crystal Structure, Fluorescence Property and Antibacterial Activity of Two Unprecedented One-dimensional Chain Metal organic Coordination Polymers： Zn（H-SSA）（Phen）（H20）2 and Cu（H-SSA） （Phen） （H20）2

The reaction of 5-sulfosalicylic acid(H3-SSA) with o-phenanthroline(Phen),NaOH,and Mcl2(M=Zn,Cu) affords Zn(H-SSA)(Phen)(H2O)2(1) and Cu(H-SSA)(Phen)(H2O)2 (2),respectively ,compounds 1 and 2 are characterized by elemental analysis,IR,fluorescence spectra and single crystal Xray diffraction analysis.The X-ray diffraction analyses reveal that compounds 1 and 2 are isostructure.The 5-sulfosalicylic acid ligand loses two protons at the sulfo-group and carboxylic group during the reaction.The Zn(II) and Cu(II)ions are sixcoordinated and adopt distorted octahedral geometry,which are surrounded by two N atoms from Phen,two O atoms from two water molecules,one O atom from-SO3 group and one oxygen from carboxylic group of the other H-SSA.Compounds 1 and 2 have unprecedented one-dimensional linear chain formed by a repeating mononuclear structureal unit.which is bridged by H-SSA.The fluorescence intensity of 1 and 2 is stronger than that of Phen and H3-SSA at 400nm.The lowest excited single states of these complexes are assigned as mainly Phen localized 1(π π),The antibacterial activity test shows that compounds 1 and 2 strongly inhibit the growth of Streptococcus haemolyticus,Straphylococcus aureus and Escherichia coli.     

Synthesis and Characterization of Poly（ether amide）s Containing Bisphthalazinone and Ether Linkages

A novel aromatic diacid, 4, 4′-bis[2-(4-carboxyphenyl)phthalazin- 1-one-4-yl]-bisphenyl ether III, containing bisphthalazinone and ether linkages was prepared from nucleophilic substitution of p-chlorobenzonitrile with the bisphenol-like monomer I, followed by alkaline hydrolysis of the intermediate dinitrile II. A series of poly(ether amide)s containing bisphthalazinone and ether linkages derived from diacid III and aromatic diamines were synthesized by one-step solution condensation polymerization using triphenyl phosphite and pyridine as condensing agents. Moreover, the properties of poly(ether amide)s including thermal stability,solubility and crystallinity were also studied.     

Synthesis of （S）-2-Ethoxy-3-Phenylpropanoic Acid Derivatives and Their Insulin-Sensitizing Activity

A series of （S）-2-ethoxy-3-phenylpropanoic acid derivatives were synthesized and their insulin-sensitizing activities were evaluated in 3T3-L1 cells. Compounds 1b, 1d, 1e and 1f exhibited more potent insulin-sensitizing activity than rosiglitazone.     

Design and Synthesis of Transparent Poly （acrylonitrile-butadiene-styrene） and Relationship Between Its Phase Construction and Transparency

IntroductionABS resins have been widely applied to the field ofengineering materials because of their excellent me-chanical,electrical,physical,and chemical proper-ties.Typically,ABS resins comprise a rigid copolymermatrix-phase dispersed in a graft copol…     

环氧丙烷聚醚三元醇/左旋聚乳酸三枝链嵌段共聚物的结晶行为

采用DSC对环氧丙烷聚醚三元醇/左旋聚乳酸三枝链嵌段共聚物(PPO-b-PLLA)的熔体结晶行为进行了研究. 在388～407 K范围内, 分别采用Avrami方程和Arrhenius方程进行了结晶动力学计算. Avrami指数n值约为2.2, 表明共聚物以二维生长方式进行晶体生长. 基于LH结晶理论, 对三枝链嵌段共聚物的结晶机理进行了探讨. 实验发现该体系共聚物的Regime II和Regime III转变温度随着n(PO)∶n(LA)的增大而变化, Kg (III)/Kg (II)＝2.0～2.2, 与LH理论预期值吻合. 实验结果表明三枝链的PPO链段对PLLA链段的结晶有很大影响, 使其成核较均聚物困难. 链折叠自由能σe和链折叠功q均高于PLLA的值.     

Self-aggregation and phase behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers in aqueous solution

The phase behavior and aggregation properties of block copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronics, poloxamers) in aqueous solution have recently attracted much attention. Both experimental and theoretical studies are reviewed, not comprehensively, but with the focus on studies, partly cooperative, partly independent, performed by groups in Uppsala (light scattering and fluorescence), Roskilde (rheology and calorimetry), Risø (SANS), Graz (x-ray and speed of sound), and Lund (theoretical model calculations).The phase behavior of these copolymers is similar in many respects to that of conventional nonionic surfactants, with the appearance of hexagonal, cubic, and lamellar liquid crystalline phases at high concentrations. In the isotropic solution phase the critical concentration for micelle formation is strongly temperature dependent, and at a given concentration the monomer to micelle transition occurs gradually over a broad temperature range, partly due to the broad size polydispersity of both the PO- and EO-blocks. For some Pluronic copolymers a transition from globular to long rod-like micelles occurs above a transition temperature, resulting in a strong and sudden increase of viscosity and viscoelasticity of the solution.Size and aggregation numbers have been determined for the globular micelles in some cases, and also the rod-like micelles have been characterized. NMR and fluorescence measurements have provided further information on the properties of the micellar core and mantle. In combination, results from different measurements on the same Pluronics material indicate that the aggregation number of the micelles increases with the temperature, whereas the hydrodynmic radius varies much less. The PEO-mantle of the micelles seems to contract with increasing temperature. The core appears to contain appreciable amounts of PEO in addition to PPO (and also some water). The segregation between core and mantle is not as distinct as in normal micelles, a conclusion which is in line with the predictions from the model calculations.     

氯化聚丙撑碳酸酯增容聚丙撑碳酸酯/秸秆粉复合材料的制备及性能

聚丙撑碳酸酯(PPC)是一种新型热塑性生物降解材料,但其热性能及力学性能较差,应用受到限制。以秸秆粉这种农作物副产品作为增强体改性PPC,既可以提高PPC的力学性能同时又可开发利用秸秆资源。氯化聚丙撑碳酸酯(CPPC)是聚丙撑碳酸酯(PPC)经过氯化得到的,对天然纤维表面具有良好的浸润性和粘结性。本文以CPPC为增容剂,通过熔融共混法制备了PPC/秸秆粉复合材料。采用扫描电子显微镜(SEM)、拉伸实验、动态力学性能测试(DMA)及转矩流变仪对复合材料的结构及性能进行了表征,重点考察了CPPC的添加量对复合材料力学和流变性能的影响。结果表明,当CPPC质量分数为1.8%时,可使添加质量分数为30%秸秆粉的PPC复合材料拉伸强度提高38%,模量提高30%。同时,CPPC的引入使复合材料的粘度下降,改善了PPC/秸秆粉复合材料的加工性能。因此,作为增容剂的CPPC为制备高性能PPC/天然纤维复合材料提供了新的解决办法。     

苯胺和环氧丙烷共聚物电催化氧化甲酸

 采用循环伏安法制备了苯胺和环氧丙烷导电高分子共聚物(PAN-PPO)电极,研究了其对甲酸氧化的电催化性能. 结果表明,PAN-PPO对甲酸氧化具有较高的催化活性,其催化性能稳定. 研究了PAN-PPO电催化甲酸氧化的动力学特征. 结果表明,甲酸在PAN-PPO上可能直接经电催化氧化生成CO2,此反应受液相扩散控制,扩散系数为1.32×10-7 cm2/s,反应级数为1.     

High yield synthesis of biodegradable poly(propylene carbonate) from carbon dioxide and propylene oxide

A novel SalenCo^III (2,4‐dinitrophenoxy) (Salen = N,N'‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamino) and 1,10‐phenanthroline monohydrate catalyst system was designed and employed for the copolymerization of CO₂ and propylene oxide (PO). The perfectly alternating copolymerization of CO₂ and PO proceeds effectively under middle temperature and pressure to yield poly(propylene carbonate) with a high yield and a high number average molecular weight of polymer. The structure of polymer was characterized by the IR and NMR measurements. The perfectly alternating copolymer was confirmed. The MALDI‐TOF spectrum insinuates that the copolymerization of CO₂ and PO was initiated by H₂O. Copyright © 2016 John Wiley & Sons, Ltd.     

N‐Heterocyclic Olefins as Organocatalysts for Polymerization: Preparation of Well‐Defined Poly(propylene oxide)

The metal‐free polymerization of propylene oxide (PO) using a special class of alkene—N‐heterocyclic olefins (NHOs)—as catalysts is described. Manipulation of the chemical structure of the NHO organocatalyst allows for the preparation of the poly(propylene oxide) in high yields with high turnover (TON>2000), which renders this the most active metal‐free system for the polymerization of PO reported to date. The resulting polyether displays predictable end groups, molar mass, and a low dispersity (?_M<1.09). NHOs with an unsaturated backbone are essential for polymerization to occur, while substitution at the exocyclic carbon atom has an impact on the reaction pathway and ensures the suppression of side reactions.     

Copolymerization of propylene oxide and CO2 using achiral salophen Co(III) penta-florobenzoate as catalyst and tetrabutyl ammonium bromide as co-catalyst

Copolymerization of racemic propylene oxide with carbon dioxide is investigated in the presence of economically inexpensive and effective achiral salophenCo(III)X [salophen = N,N'-bis(3,5-di-tert-butylsalicylidene)-phenylenediimine, X = pentaflorobenzoate] catalyst and tetrabutyl ammonium bromide as co-catalyst. Effects of different variables like monomer to catalyst ratio, catalyst/co-catalyst ratio, temperature, pressure of CO₂ on molecular weight, yield and selectivity of poly(propylene carbonate) [PPC] have been investigated. The maximum M_w of 25.8 g/mol has been obtained at 15 bar and 50°C. All the samples were found to have excellent polydispersity near to 1.     

环氧丙烷聚醚三元醇/聚乳酸嵌段共聚物的合成与性能

以低不饱和度环氧丙烷聚醚三元醇与L型及DL型丙交酯为原料, 合成了不同单体物质的量比的聚醚与聚乳酸嵌段共聚物. 采用FTIR, 1H NMR, GPC对共聚物的结构进行了表征; 用DSC, DTA对共聚物的玻璃化转变温度、熔点及热分解温度进行了研究. 结果表明, 丙交酯在聚醚多元醇端羟基的引发下发生开环反应, 得到聚环氧丙烷L型乳酸(POLLA)或聚环氧丙烷DL型乳酸(PODLA)二嵌段共聚物. POLLA二嵌段共聚物具有结晶能力, 且随着L型聚乳酸链段的增长而增强. PODLA二嵌段共聚物为非晶态聚合物. 两种共聚物的玻璃化转变温度与共聚物的组成有关, 其值介于聚醚和聚乳酸玻璃化转变温度之间. 与聚醚三元醇相比, 二嵌段共聚物的耐热性得到提高, 其热分解温度提高了30～60 ℃, 约为235～262 ℃. 共聚物的结构和组成对材料的热降解机制有很大影响. PODLA在高温区发生热氧化降解.     

Alternating copolymerization of propylene oxide and carbon dioxide with highly efficient and selective (salen)Co(III) catalysts: Effect of ligand and cocatalyst variation

Synthetic routes to a series of new (salen)CoX (salen = N,N′-bis(salicylidene)-1,2-diaminoalkane; X = Br or pentafluorobenzoate (OBzF₅)) species are described. Several of these complexes are active for the copolymerization of propylene oxide (PO) and CO₂, yielding regioregular poly(propylene carbonate) (PPC) without the generation of propylene carbonate byproduct. Variation of the salen ligand, as well as the inclusion of organic-based ionic or Lewis basic cocatalysts, has dramatic effects on the resultant (salen) CoX catalytic activity. Highly active (R,R)-(salen- 1 )CoOBzF₅ (salen- 1 = N,N′-bis(3,5- di-tert-butylsalicylidene)-1,2-diaminocyclohexane) catalysts with [Ph₄P]Cl or [PPN]Y ([PPN] = bis(triphenylphosphine)iminium; Y = Cl or OBzF₅) cocatalysts exhibited turnover frequencies up to 720 h⁻¹ for rac-PO/CO₂ copolymerization, yielding PPC with greater than 90% head-to-tail connectivity. Additionally, the (R,R)-(salen- 1 )CoOBzF₅/[PPN]Cl catalyst system demonstrated a k_rel of 9.7 for the enchainment of (S)- over (R)-PO when the copolymerization was carried out at low temperatures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5182–5191, 2006