Preparation of polypyrrole/sulfonated-poly(2,6-dimethyl-1,4-phenylene oxide) conducting composites and their electrical properties

The conducting composites were prepared by chemical oxidative polymerization using pyrrole and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) or sulfonated-poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) in chloroform. The pyrrole was protonated and polymerized using iron(III) chloride (FeCl₃). The electrical conductivities of PPy/SPPO composites were increased up to 1 order with the amount of PPy compared to PPy/PPO composites. The introduction of sulfuric group to PPO results in the Coulombic interaction between each phase of composites. As a result, the electrical conductivities might be increased due to the effect of miscibility between each phase. The electrical conductivity of PPy/SPPO composite was increased up to 2.14 S/cm with amount of 25 wt.% PPy. The performance of charge–discharge of PPy/SPPO electrode was much higher than that of PPy/PVdF electrode because SPPO act as a dopant as well as a binder.     

空心聚吡咯/V_2O_5复合材料的制备及其电化学性能

为改善晶态V2O5（c-V2O5）正极材料实际容量较低、循环性能较差等问题,制备了空心球聚吡咯/V2O5复合材料。利用导电吡咯单体（Py）在中空型V2O5层间发生原位氧化聚合反应制备聚吡咯（PPy）/中空型V2O5复合材料（HS-PPy/V2O5）。采用X射线衍射仪（XRD）、扫描电镜（SEM）、透射电镜（TEM）对样品进行表征,采用恒流充放电测试和电化学阻抗（EIS）测试样品的电化学性能。结果表明,Py单体已插入中空型V2O5层间,与纯中空型V2O5相比,制备的HS-PPY/V2O5复合材料比容量虽然有所减小,但是循环稳定性有较大的提高。     

Room temperature synthesis of Ag/polypyrrole core–shell nanoparticles and hollow composite capsules

Two kinds of Ag/polypyrrole composite nanoparticles have been prepared via a one-step redox reaction between silver nitrate and pyrrole monomer at room temperature. One is Ag@polypyrrole core–shell nanoparticles that were synthesized by making use of synergic inducing effect of polyvinyl pyrrolidone and p-toluenesulfonic acid existing in aqueous solutions. The other is AgCl@Ag/polypyrrole core–shell composite nanoparticles that were synthesized in the presence of HCl using the in situ-formed AgCl particles as the template. For the latter, its core can be easily removed via a simple dissolving procedure in sodium hyposulfite or ammonium chloride aqueous solutions, obtaining the Ag/polypyrrole hollow composite capsules. Experimental results suggest that the shell thickness and core diameter of the resulting composites can be controlled expediently by adjusting reaction time and concentration of pyrrole monomer.     

Spectral and adsorption characteristics of Au(III) and Au(0) composite materials

The adsorption of HAuCl₄ chloroauric acid on silica modified with γ-aminopropyltriethoxysilane (aminosilica) and on aluminum oxide is studied. Diffuse-scattering spectra of these Au(III) composite materials and their reduced Au(0) composites are recorded in the visible and infrared spectral ranges. Au(III) composites are selective with respect to the adsorption of phenylacetylene (PA) from octane due to the formation of π-complexes with Au(III). Au(III)-aluminum oxide composite material has a much larger capacity for PA adsorption than does aminosilica composite with the same gold content. The formation of coordination bonds between free aminopropyl groups of the silica carrier and gold atoms prevents PA adsorption. The formation of such bonds is manifested in a shift in λ_max of the spectral line from 408 to 522 and 546 nm with a decrease in [Au(III)] concentration from 400 to 120 and 60 μmol/g. The decrease in the intensity and the red shift of the absorption bands of NH₂ stretching vibrations in the infrared spectra of the specimen upon modification also confirms the supposition. There are absorption bands of free hydroxyl radicals, but no band of bound radicals in the infrared spectra of Au(0) composites. The electronic spectra (λ_max = 511, 504, and 512 nm) are close for all three specimens that differ in gold content, which means that the sizes of immobilized Au(0) nanoparticles are similar. Upon the sorption of HAuCl₄ on a Au(III)-aluminum oxide specimen, the absorption band of surface OH groups disappears, however, in Au(0) composite, it appears again near 3105 cm^?1.     

Au/Al_2O_3层状复合纳米涂层的制备及其抗氧化性能(英文)

采用磁控溅射法成功制备Al2O3/Au层状复合纳米涂层,所制备的涂层结构致密且由Al2O3层和Au层交替组成。采用高温循环氧化实验对复合涂层在不锈钢基体上的高温抗氧化性能进行分析评价。结果表明:Al2O3/Au层状复合纳米涂层极大地改善不锈钢基体的抗氧化和抗剥落性能。其抗氧化机理与涂层能够有效地抑制氧向合金基体的扩散并促进不锈钢基体中Cr元素的选择性氧化有关;抗剥落机理可归因于复合涂层中的Au层和纳米结构的Al2O3层能够有效地松弛高温热循环过程中产生的热应力,从而提高涂层的抗剥落性能。     

碳包覆镍纳米颗粒/聚苯胺复合材料的制备及电磁性能

以纤维素为炭前躯体,硝酸镍为金属源,采用还原炭化法制备出碳包覆Ni纳米颗粒(Ni@C)。进一步采用原位聚合法合成出Ni@C/聚苯胺(PANI)复合材料。TEM分析表明:Ni@C粒度分布均匀,呈核壳结构。采用IR光谱、SEM、XRD对复合材料和形态和结构进行分析;考察了Ni@C的含量对Ni@C/PANI复合材料电导率的影响。采用波导法在8.2-12.4 GHz波段范围对Ni@C和Ni@C/PANI复合材料进行电磁参数进行测试分析,复合材料的电损耗角正切值可达到0.65,磁损耗角正切值可达0.15,所制备Ni@C/PANI具有较高的电磁损耗角正切值,结果表明其吸波性能较好。     

Preparation of one-dimensional (1D) polyaniline–polypyrrole coaxial nanofibers and their application in gas sensor

A facile and low-cost method has been developed to prepare one-dimensional (1D) polyaniline–polypyrrole (PANI–PPy) coaxial nanofibers (PPCF). The morphology and molecular structure of PPCF were proved by scanning electron microscopy, transmission electron microscopy, EDX, UV–vis, FTIR and Raman spectroscopy. A possible synthetic scheme for the synthesis of PPCF has been proposed. The electrical responses of PPCF to triethylamine (TEA) vapor were measured at room temperature. It was found that PPCF showed a rapid, sensitive and reversible conductance change upon exposure to TEA vapor at concentrations ranging from 1 to 1000 ppm. The results suggested that the comprehensive performance of the gas sensor using PPCF was better than the results obtained using PANI nanofibers and PPy separately. In addition, a sensing mechanism was proposed.     

NaBH_4的水性还原法制备纳米铜颗粒(英文)

在碱性溶液中用NaBH4还原Cu2+制备纳米铜颗粒,研究NaBH4浓度和滴加速率对Cu纳米颗粒制备的影响。反应的最佳条件是:0.2mol/LCu2+,溶液pH12,温度313K,1%明胶作为分散剂,将0.4mol/LNaBH4溶液以50mL/min的速率加入CuSO4溶液中。氨水是最佳的络合剂。采用一系列实验研究不同时间点的反应进程。     

金属纳米颗粒分散氧化物Au/SiO2薄膜的制备与光吸收特性

利用多靶磁控溅射法制备了金纳米颗粒分散氧化物薄膜,其分散颗粒的体积分数和平均直径分别为3%～65%和10nm～30nm.吸收光谱研究表明,Au/SiO2薄膜在560nm波长附近有明显的表面等离子共振吸收峰,吸收峰的强度随Au含量的增加而增强,Au含量在37%的附近,Au/SiO2薄膜在560 nm波长处表现的吸收峰呈最大的吸收强度.当Au分散颗粒的含量超过了其分散限度后,吸收峰的强度随Au含量的增加而减弱.用Mie散射理论对吸收光谱进行了模拟,得到了与实验结果一致的表面等离子共振吸收峰.     

Catalytic synthesis of conductive polypyrrole using iron (III) catalyst and molecular oxygen

The catalytic oxidative polymerization of pyrrole was developed by the use of a relatively small amount of iron(III) salts as a catalyst and molecular oxygen as an oxidant. The reaction rate depended on the solvent used. Thus, the organic solvent with high dielectric constant gave the polymer with high electroconductivity at high yield. In contrast, both the polymerization rate and the conductivity of the produced polymer were low when the solvent with low dielectric constant was used. When propylene carbonate was used as the solvent with high dielectric constant, the turnover number reached about 10 in 96 h based on the charged amount of catalyst, and the highest electroconductivity around 10⁻² S cm⁻¹ was achieved without extra doping. The addition of the quaternary ammonium salt to the reaction mixture improved the conductivity. Results on cyclic voltammetry suggested that the redox potential of iron ions depending on the solvent is an important factor to determine the efficiency of the catalytic polymerization of pyrrole.     

Nanoscale photoluminescence of light-emitting poly (3-methylthiophene) nanotubes hybridized with Au nanoparticles

We reported on the fabrication and nanoscale luminescence characteristics of the hybrid nanotubes (NTs) of light-emitting poly (3-methylthiophene) (P3MT) NT with gold (Au) nanoparticles (NPs) (P3MT/Au-NPs). After hybridizing the Au-NPs onto the surface of P3MT NTs, the light-emitting color of P3MT NTs was dramatically changed from a green to a bright red. From laser confocal microscope photoluminescence (PL) experiments for an isolated single strand of the NTs, we observed a ～220 times enhancement of the PL peak intensity for the hybrid NT of P3MT/Au-NPs compared to that of the P3MT single NT. The enhancement PL efficiency of the hybrid NT of P3MT/Au-NPs can be explained in terms of a surface plasmon resonance (SPR) and nanoscale local electric field enhancement effects.     

Preparation and properties of conducting composites of polypyrrole and porous cross-linked polystyrene with and without supercritical carbon dioxide

Composites of polypyrrole (PPy) and porous cross-linked polystyrene (PCPS) were prepared using a two-step batch method proposed by Ruckenstein and Park. However, the solvent employed by Ruckenstein and Park (methanol) in the polymerization step of their method was replaced with supercritical CO₂. For comparison purposes, PPy/PCPS composites were also prepared using no solvent in the polymerization step. Conductivities as high as 10⁻² S cm⁻¹ were obtained, with or without the use of supercritical CO₂. Uniformity of conductivity was determined via surface and bulk conductivity measurements, as well as by a new volume conductivity measurement that provides a measure of spatial (three-dimensional) distribution of the conducting component in the composite.The conductivity of composites prepared with or without the use of supercritical CO₂ conformed to the same percolation behavior with respect to the amount of PPy formed. The percolation threshold in all cases was as low as 4 wt.%. The mechanical strength of the composites was found to be about the same as that of the host PCPS, as was the thermal stability. Therefore, the conductive component did not appear to adversely affect these properties of the host. Finally, the temperature behavior of the conductivity could be correlated with Mott's variable-range hopping (VRH) model for three-dimensional electronic transport.     

Preparation and application of hydroxyapatite(HA) nanoparticles/NR2B-siRNA complex

Hydroxyapatite(HA) nanoparticles were prepared by coprecipitation-hydrothermal synthesis and their exosyndrome was estimated via transmission electron microscopy. Agarose gel electrophoresis and ultraviolet spectrophotometry were used to evaluate the ability of HA to bind NR2B-siRNA at different pH values and at different HA-NR2B-siRNA ratios. And the stability of the complex in saline was also evaluated. The effect of HA/NR2B-siRNA complex on chronic inflammatory pain was evaluated in vivo in mice. Transmission electron microscopy(TEM) reveals that HA nanoparticles are thin strips or short rod in shape and the one-dimensional particle size of HA nanoparticles is 40-50 nm. Under the acid or neutral condition, the Zeta potential of HA is positive; nanoparticles can completely bind NR2B-siRNA when the HA:NR2B-siRNA ratio is at or larger than 35-1; while under the alkaline condition, the affinity of HA to NR2B-siRNA is rather weak. HA/NR2B-siRNA complex is not dissociated when being resuspended in saline. The nociception of the tonic phase induced by formalin is significantly reduced in the HA/NR2B-siRNA treated mice as compared with the controls. Therefore, HA may be a new siRNA nano-vector material.     

Preparation and electrochemical performances of graphite oxide/polypyrrole composites

Graphite oxide/polypyrrole composites (GPys) were prepared by in situ polymerization and reduced by NaBH₄ to prepare reduced graphite oxide/polypyrrole composites (R-GPys). On the basis of the morphological and structural characterization of the composites by Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests, the electrochemical performances of the composites were investigated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance techniques. The experimental results showed that the specific capacitances of the composites before and after reduction (197 and 180 F/g) were highly improved compared with that of pristine graphite oxide (11 F/g) and polypyrrole (112 F/g), respectively. The capacitance retention of about 73% for R-GPys compared with 12% for PPy and 47% for GPys after 1200 cycles indicated the high cycle stability of the R-GPys and its potential as an electrode material for supercapacitor applications.     

A novel route to synthesis of photoluminescent dye/polypyrrole nanoparticles: Effects of intermolecular energy transfer on nucleation and growth of polypyrrole

Photoluminescent dye/polypyrrole nanoparticles were prepared by one-step polymerization of pyrrole monomer in the presence of the dye molecules under UV light illumination. Oxygen in the air was selected as an oxidant in this method. Optical properties of the nanoparticles were investigated, revealing that the nanoparticles exhibited higher photostability than pure RhB. In addition, it was found that the presence of both dye molecules and UV light played the important role in the formation of the nanoparticles. And then the mechanism for the formation of well-confined nanoparticles was explained via the effects of intermolecular energy transfer between the dye molecules and pyrrole monomer on nucleation and growth of polypyrrole.     

Cyclic voltammetrically prepared MnO2–PPy composite material and its electrocatalysis towards oxygen reduction reaction (ORR)

A composite material containing manganese dioxide and polypyrrole (denoted as MnO₂–PPy) was successfully fabricated onto a graphite substrate by cyclic voltammetry (CV) technique from a 0.5 M H₂SO₄ solution having 0.2 M pyrrole (Py) and 0.2 M MnSO₄. Results obtained from cyclic voltammograms (CVs) and charge–discharge curves demonstrated that this composite material can be utilized as a satisfied supercapacitance material due to its excellent charge-storage ability and reversibility of charging–discharging. Scanning electron microscopy (SEM) images revealed that more packed materials were obtained when MnO₂ was formed among polypyrrole. And for the first time, this composite was employed to ORR, and results obtained from CVs demonstrated that this composite has electrocatalysis towards ORR in an acid solution of 0.5 M H₂SO₄ when compared to the pure PPy.     

通过水溶液还原法用抗坏血酸制备纳米铜颗粒(英文)

通过水溶液还原法用抗坏血酸还原Cu2+制备纳米铜颗粒,并研究溶液pH和Cu2O平均粒径对纳米铜颗粒制备的影响。在溶液pH值为3、5和7时,可制得铜颗粒,并且在pH=7时制得的铜颗粒粒径最小。在溶液pH为9和11时无法制得铜颗粒。Cu2O的平均粒径能影响铜粉的粒径。Cu2O的平均粒径越大,得到的铜颗粒越大。通过对反应过程中不同时间点收集的样品进行XRD分析,可探索出反应的进程。在反应过程中,Cu(OH)2首先作为前驱体出现,然后被还原为Cu2O,最后被还原为铜颗粒。     

纯相低氧纳米WC-Co复合粉的制备

以紫钨、四氧化三钴、炭黑为原料,在高真空度条件下利用原位反应合成技术制备出物相纯净、平均粒径约为80 nm的WC-Co复合粉。研究了制备工艺参数对纳米复合粉相组成、粒径、氧含量及最终烧结硬质合金块体材料组织性能的影响。结果表明,纳米复合粉中氧含量较高时,会导致后续烧结过程中发生脱碳反应,使烧结制备的块体材料致密度和力学性能明显下降。将纳米复合粉在800℃下真空热处理2.5 h可有效降低粉末中的氧含量,同时热处理后的粉末颗粒无明显长大,平均粒径为85 nm。向复合粉中加入1.1%TiC与0.9%VC进行SPS烧结,烧结块体平均晶粒尺寸为105 nm,且尺寸分布均匀,致密度达99%以上,硬度(HV30)为21 450 MPa,断裂韧性达到9.81 MPa·m~(1/2)。     

氧化铋/二氧化钛复合颗粒的制备及其光催化降解4-氯苯酚的性能

在低温条件下制备在太阳光照射下具有高光催化活性的氧化铋/二氧化钛复合颗粒。并利用XRD、SEM、BET、XPS和DRS对其进行表征。结果表明：将二氧化钛纳米颗粒沉积在氧化铋表面可形成微-纳结构,使该复合材料表现出多孔性,并提高表面羟基的含量。因此,在太阳光的激发下,氧化铋/二氧化钛复合颗粒对4-氯苯酚的催化降解能力高于纯二氧化钛和P25。     

Au／TiO2催化剂的制备及低级醇类的光催化消除

采用沉积-沉淀法制备Au/TiO2催化剂,并用IR、TG-DTA、XRD、TEM、BET、FL、XPS、UV-vis DRS和PL等分析方法对其进行表征;测试和计算在甲醇的光催化消除反应中Au/TiO2催化剂的动力学参数;以低级醇类消除反应为模式反应评价催化剂在紫外光照下的光催化性能.结果表明:Au质量分数为1%的Au/TiO2催化剂在200 ℃下活化4 h的光催化活性最佳,0.15 g催化剂可将初始浓度为7.0 g/m3、流速为12.5 mL/min的甲醇和初始浓度为2.14 g/m3、流速为5 mL/min的乙醇以及初始浓度为2.21 g/m3、流速为4 mL/min的正丙醇完全消除;得到的反应活化能Ea = 14.80 kJ/mol,拟合的曲线线性关系好(R = 0.981 1),符合一级动力学反应规律.