Sulfonated poly(aryl ether ether ketone ketone)s containing fluorinated moieties as proton exchange membrane materials

A series of sulfonated poly(aryl ether ether ketone ketone)s statistical copolymers with high molecular weights were synthesized via an aromatic nucleophilic substitution polymerization. The sulfonation content (SC), defined as the number of sulfonic acid groups contained in an average repeat unit, could be controlled by the feed ratios of monomers. Flexible and strong membranes in sodium sulfonate form could be prepared by the solution casting method, and readily transformed to their proton forms by treating them in 2 N sulfuric acid. The polymers showed high T_gs, which increased with an increase in SC. Membranes prepared from the present sulfonated poly(ether ether ketone ketone) copolymers containing the hexafluoroisopropylidene moiety (SPEEKK‐6F) and copolymers containing the pendant 3,5‐ditrifluoromethylphenyl moiety (SPEEKK‐6FP) had lower water uptakes and lower swelling ratios in comparison with previously prepared copolymers containing 6F units. All of the polymers possessed proton conductivities higher than 1 × 10^?2 S/cm at room temperature, and proton conductivity values of several polymers were comparable to that of Nafion at high relative humidity. Their thermal stability, oxidative stability, and mechanical properties were also evaluated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2299–2310, 2006     

Preparation and characterization of rigid poly(vinyl chloride)/MMT nanocomposites. II. XRD,morphological and mechanical characteristics

A Haake torque rheometer equipped with an internal mixer is used to study the influence of the amount of sodium montmorillonite (Na⁺‐MMT) and organically modified MMT (O‐MMT) on X‐ray diffraction (XRD), morphology, and mechanical characteristics of rigid poly (vinyl chloride) (PVC)/Na⁺‐MMT and PVC/O‐MMT nanocomposites, respectively. Results of XRD and transmission electron microscopy (TEM) indicate that MMT is partially encapsulated and intercalated in the rigid PVC/Na⁺‐MMT nanocomposites. However, results of XRD and TEM show MMT is partially intercalated and exfoliated in the rigid PVC/O‐MMT nanocomposites. Tensile strength, yield strength, and elongation at break of the rigid PVC/MMT nanocomposites were improved simultaneously with adding 1–3 wt % Na⁺‐MMT or O‐MMT with respect to that of pristine PVC. However, the addition of Na⁺‐MMT or O‐MMT should be kept as not more than 3 wt % to optimize the mechanical properties and the processing stability of the rigid PVC/MMT nanocomposites. SEM micrographs of the fractured surfaces of the rigid PVC/Na⁺‐MMT and PVC/O‐MMT nanocomposites both before and after tensile tests were also illustrated and compared. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2145–2154, 2006     

Characterization and electrical properties of polypyrrole/multiwalled carbon nanotube composites synthesized by in situ chemical oxidative polymerization

This study describes the preparation of polypyrrole (PPy)/multiwalled carbon nanotube (MWNT) composites by in situ chemical oxidative polymerization. Various ratios of MWNTs, which served as hard templates, were first dispersed in aqueous solutions with the surfactant cetyltrimethylammonium bromide to form micelle/MWNT templates and overcome the difficulty of MWNTs dispersing into insoluble solutions of pyrrole monomer, and PPy was then synthesized via in situ chemical oxidative polymerization on the surface of the templates. Raman spectroscopy, Fourier transform infrared (FTIR), field‐emission scanning electron microscopy (FESEM), and high‐resolution transmission electron microscopy (HRTEM) were used to characterize the structure and morphology of the fabricated composites. Structural analysis using FESEM and HRTEM showed that the PPy/MWNT composites were core (MWNT)–shell (PPy) tubular structures. Raman and FTIR spectra of the composites were almost identical to those of PPy, supporting the idea that MWNTs served as the core in the formation of a coaxial nanostructure for the composites. The conductivities of these PPy/MWNT composites were about 150% higher than those of PPy without MWNTs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1413–1418, 2006     

Electrochemical characteristics of gatifloxacin and its interaction with DNA.

The electrochemical behavior of gatifloxacin (GTFX) and its interaction with natural calf thymus DNA (ctDNA) is investigated by differential pulse voltammetry (DPV) on a carbon paraffined electrode. According to the suggested electrochemical equation, a binding constant of 1.7058 x 10(5) (mol L(-1))(-1) and binding sizes s = 3.09 (base pairs) of GTFX with ctDNA are obtained by nonlinear fit analysis of electrochemical data. The results demonstrate that GTFX has the properties of an intercalative binder.     

800nm激光泵浦掺Nd^3＋的氟化物玻璃光纤正向双程超荧光分析

从实验上探讨了掺Ｎｄ＾３＋的氟化物玻璃光纤正向双程超荧光基本特性，包括输入－输出特性、输出－带宽特性以及输出－波长（激发）特性。并给出了理论上的拟合公式，实验表明利用氟化物玻璃光纤有望获得性能优异的有应用前景的低相干度集成化光源。     

Cartesian currents,weak diffeomorphisms and existence theorems in nonlinear elasticity

Summary In this paper we introduce some new classes of functions, among these a class of weak diffeomorphisms. In these classes we prove by direct methods the existence of minimizers for several kinds of variational integrals. In particular, we prove the existence of one-to-one orientation-preserving maps that minimize suitable energies associated with hyperelastic materials. The minimizers are also proved to satisfy equilibrium equations. Finally radial deformations are discussed in connection with cavitation.     

Amperometric flow-injection analysis of hydrazine by electrocatalytic oxidation at cobalt tetraphenylporphyrin modified electrode with heat treatment

Chemically modified electrodes prepared by treating the cobalt tetraphenylporphyrin modified glassy-carbon electrode at 750 degrees (HCME) are shown to catalyze the electrooxidation of hydrazine. The oxidation occurred at +0.63 V vs. Ag/AgCl (saturated potassium chloride) in pH 2.5 media. The catalytic response is evaluated with respect to solution pH, potential scan-rate, concentration dependence and flow-rate. The catalytic stability of the HCME is compared with that of the cobalt tetraphenylporphyrin adsorbed glassy-carbon electrode. The stability of the HCME was excellent in acidic solution and even in solutions containing organic solvent (50% CH(3)OH). When used as the sensing electrode in amperometric detection in flow-injection analysis, the HCME permitted sensitive detection of hydrazine at 0.5 V. The limit of detection was 0.1 ng. The linear range was from 50 ng to 2.4 mug. The method is very sensitive and selective.     

Chiral Salen Manganese Complex Immobilized on SBA-15： A New Heterogenized Enantioselective Catalyst for the Epoxidation of Alkenes

Jacobsen‘s catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times.     

付里叶变换红外光谱仪的操作参数对光谱的影响

本文以二苯基甲酮的ＫＢｒ压片为标样，在Ｂｒｕｋｅｒ ＩＦＳ １２０ＨＲ付里叶变换红外光谱仪上系统考察了该仪器折一些重要操作参数（光源光栏、切趾函数、扫描速度）对光谱质量（信噪比，分辨率）的影响。从而获得了测样时的优化操作条件。