KF/Al_2O_3协同TBHPAS固液相转移催化己内酰胺和酰亚胺的N烃基化反应

利用 KF/Al2 O3协同 TBHPAS,在固液相转移催化条件下进行己内酰胺和酰亚胺的 N烃基化 ,收率分别为 92 %～ 96%和 82 %～ 96% ,该方法简单 ,操作方便 ,是一种较为理想的 N 烃基化方法     

Thermal decomposition characteristics of poly(ether imide) by TG/MS

Thermal degradation of poly(ether imide) (PEI) was studied by the combination of pyrolysis/gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis/mass spectrometry (TG/MS) techniques. The composition of evolved gases was determined by Py-GC/MS and the real-time formation curves were obtained through TG/MS. The thermal degradation mechanisms of PEI were resolved through TG/MS methods. The major pyrolysis mechanisms with the two-stage reaction regions were main chain random scission and carbonization. In the first stage pyrolysis, the decomposition of the hydrolyzed-imide, ether and isopropylene groups caused the evolution of CO₂ and phenol as major products accompanied by a chain transfer of carbonization to form partially carbonized solid residue. In the second stage pyrolysis, the decomposition of partially carbonized solid residue and the remaining imide group produced CO₂ as a major product along with benzene and small a amount of benzonitrile. Afterward, the chain transfer of carbonization dominated the decomposition of solid residue in higher temperatures to produce a high char yield. A kinetic model was proposed from the calculation of two flat regions in the activation energy curve. The theoretical pyrolysis curve from the proposed model was calculated and compared with the experimental curve, which were quite well matched.     

Flexible blend polymer electrolyte membranes with excellent conductivity for fuel cells

Polymer electrolyte membrane with high conductivity is an indispensable need in fuel cell applications due to some major drawbacks of the commonly used polymer electrolytes. Herein, we have synthesized two thermally and chemically stable polymer electrolytes; poly(2,5-dioxo-2,5-dihydro-1H-pyrrole-1-carbonyl)sulfamoyl fluoride-co-styrene) (PDDPCSFS), and sulfonated Pmax-1200 (SPmax-1200). PDDPCSFS and SPmax-1200 showed (70.50 and 75.44) mS/cm proton conductivity (σ), (30 and 48)% water uptake (WU), and (1.35 and 1.93) meq./g ion exchange capacity (IEC) value, respectively, at 80 °C. We also prepared blend polymer electrolytes by blending PDDPCSFS and SPmax-1200 polymer with different ratios and observed that the blend polymer electrolytes exhibited enhanced performances compared to their parent's compounds by forming an excellent ion-conducting channel. The blend polymers, Blend (9:1), and Blend (8:2) exhibited excellent IEC (2.09 and 2.19) meq./g, σ (93.14 and 117.50) mS/cm at 80 °C under 80% relative humidity (RH), mechanical, and chemical stability, which are higher or comparable to Nafion 117. Moreover, the maximum power density of fuel cells with Blend (9:1) and Blend (8:2) polymer electrolytes was ca. (0.55 and 0.59) W/cm², respectively, which are very close to the power density of fuel cell with commercial polymer electrolyte. Therefore, these blend polymer electrolytes can be used as effective proton conductive materials for fuel cell applications.     

Novel poly(thiourea‐ether‐imide)s derived from 4,4′‐oxydiphenyl‐bis(thiourea): probing the possibility for high‐temperature applications

Our interest in the fabrication of high‐performance polyimides has led to thiourea‐substituted poly(thiourea‐ether‐imide)s (PTEIs) with good retention of thermal properties along with flame retardancy. A new aromatic monomer, 4,4′‐oxydiphenyl‐bis(thiourea) (ODPBT), was efficiently synthesized and polymerized with various dianhydrides (pyromellitic dianhydride, 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 4,4′‐(hexafluoroisopropylidene)diphthalic dianhydride) via two‐stage chemical imidization to fabricate a series of PTEIs. The structural characterization of ODPBT and the polymers was carried out using Fourier transform infrared, ¹H NMR and ¹³C NMR spectral techniques along with crystallinity, organosolubility, inherent viscosity and gel permeation chromatographic measurements. PTEIs bearing C?S and ? O? moieties in the backbone demonstrated an amorphous nature and were readily soluble in various amide solvents. The novel polymers had inherent viscosities of 1.16–1.23 dL g^?1 and molecular weights of ca 90 783–96 927 g mol^?1. Their thermal stability was substantiated via 10% weight loss in the temperature range 516–530 °C under inert atmosphere. The polyimides had glass transition temperatures of 260–265 °C. Incorporation of thiourea functionalities into polymer backbones is demonstrated to be an effective way to enhance their thermal properties and flame retardancy. Thus, ODPBT can be considered as an excellent candidate for use in the synthesis of high‐performance polymeric materials. Copyright © 2010 Society of Chemical Industry     

Chemical linkage functions of poly(ether imide)s on the resistive switching memory effects

A series of aromatic poly(ether imide)s, AZTA-PEIs containing triphenylamine and 1,2,4-triazole moieties are prepared and characterized. All the polymers with inherent viscosity from 0.58 to 1.1 dL/g show glass transition temperatures in the range of 250–278 °C. Resistive switching memory devices are constructed based on the processable poly(ether imide) (AZTA-PEIa). The device can be switched from the initial OFF state to the ON state under either positive or negative electrical sweep at about ±3.2 V. The ON state is nonvolatile and can maintain the high conducting state even turning off the electrical power and applying a reverse bias. The device fulfills the requirements of a write-once read-many times memory (WORM) with a high ON/OFF current ratio up to 10⁵ and a long retention time in both ON and OFF states. The bistable switching effects of the polymer result from the conformation-coupled charge transfer from electron donors (triazole-substituted triphenylamine moieties) to electron acceptors (phthalimide moieties). By comparing with the memory behaviors of analogue polymers, the functions of ether and imide in the chemical polymer structure on the memory behaviors are discussed.     

Fast cycling of Li/LiCoO2 cell with low-viscosity ionic liquids based on bis(fluorosulfonyl)imide [FSI]

A charge–discharge cycling test of a Li/LiCoO₂ cell containing ionic liquids based on bis(fluorosulfonyl)imide ([FSI]⁻) as the electrolyte media, revealed significantly better rate properties compared to those of cells using conventional ionic liquids. The use of an 1-ethyl-3-methylimidazolium (EMI⁺) salt permitted the retention of 70% of the discharge capacity at a 4 C current rate. In contrast, similar performance of cells containing N-methyl-N-propylpyrrolidinium (Py₁₃⁺) and N-methyl-N-propylpiperidinium (PP₁₃⁺) salts of [FSI]⁻ was limited to operation at 2 and 1 C current rates, respectively. However, the charge/discharge cycling stability of the cell with Py₁₃[FSI] was much better than that of the cell using EMI[FSI].     

系列功能化离子液体的合成表征及其性质研究

通过两步法合成了含不同阴离子的系列含酯基官能团的咪唑类离子液体,用核磁共振、红外光谱、元素分析对其进行了结构表征,证明了该合成方法的可靠性;对功能化离子液体的基本物化性质及热稳定性等进行了全面研究,并选择了含有相同烷基的未功能化离子液体1-丁基-3-甲基咪唑四氟硼酸盐进行对比,发现酯基官能团的引入,使烷基咪唑类离子液体展现出不同的物化特性。所合成的含酯基功能化离子液体为进一步开展离子液体的各方面研究提供了全新的材料并打下了一定基础。     

Influence of flexible oligo(tetrafluoroethene) segment on the sorption and diffusion of carbon dioxide in poly(amide‐imide) membranes

Molecular simulations have been used to study the sorption and diffusion properties of carbon dioxide in a series of poly (amide‐imide) (PAI) membranes containing oligo(tetrafluoroethene) segment with various numbers (n = 0, 1, 2, 3, and 4) of tetrafluoroethene units. The solubility and self‐diffusion coefficients were computed by the Grand Canonical Monte Carlo (GCMC) method and molecular dynamics (MD) simulations respectively. It was found that increasing the fluorine content of the polymer membrane reduced the associated glass transition temperature (T_g) and led to an increase in diffusion coefficient of carbon dioxide. Results indicate that penetrant molecule's diffusion coefficient is strongly dependent on chain mobility. It is also noticed that the radial distribution functions (RDFs) are inconsistent with the d‐spacings of PAIs calculated form X‐ray data. This is also thought to be tied to the number of degrees of freedom of the chain. Finally, this study gives a useful insight into how PAIs with high fluorine content can be tailored with a high permeability to carbon dioxide. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

含酰亚胺结构聚酰胺的合成研究

通过偏苯三酸酐与11-氨基十一酸反应,制备了酰亚胺酸,经与己二胺聚合合成了含酰亚胺结构的聚酰胺,详细探讨了反应时间、脱水时间、脱水温度、投料比等反应条件对聚合物结构的影响,确定了最佳合成条件.合成产物具有比尼龙11高的耐热温度.     

Electrochemical study of double-walled carbon nanotube electrode/block polyether-lithium bis(trifluorosulphonyl)imide salt polymer electrolyte interface

Electrodes of double-walled carbon nanotubes functionalized with ∼5 mass% of carboxyl groups (DWCNT-COOH) were prepared as an entangled and porous mat structure to facilitate the infiltration of polymer electrolytes. A system composed by a block copolymer of polyethylene-b-poly(ethylene oxide) or PE-b-PEO with lithium bis(trifluorosulphonyl)imide salt was optimized with respect to salt concentration. The 25 mass% of polymer electrolyte-DWCNT-COOH composite showed typical electronic conductivity of carbon nanotube-based composites (i.e., conductivities of 10⁻² S cm⁻¹ were obtained). The Nyquist plots for the nanocomposite led to the assignment of separate semi-circles to the electronic transfer through the nanotube and at the polymer electrolyte–nanotube interface. A complete cell with two electrode nanocomposites and a polymer electrolyte layer was tested in a wide range of cell potentials and temperatures. The operation of this configuration at 100 °C and a 4 V window was demonstrated.