Doping of processable conducting poly(m‐aminophenol) with silver nanoparticles

Processable poly(m‐aminophenol) (PmAP) was synthesized using ammonium persulfate (APS) oxidant in 0.6 M sodium hydroxide solution at room temperature. Soluble silver hydroxide ammonium complex was formed by dissolving silver nitrate in excess liquor ammonia and the thermal decomposition of this complex easily produced silver nanoparticle. Then, in situ silver nanoparticle‐doped PmAP film was obtained by casting PmAP film from dimethyl sulfoxide (DMSO) with silver hydroxide ammonia complex mixture at 140°C. The nanocomposite was characterized by ultraviolet‐visible spectroscopy, Fourier transformed spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, electron dispersion spectroscopy, thermogravimetric analysis, and X‐ray diffraction analysis. The average size of the nanoparticle was around 130–140 nm as confirmed by the TEM analysis. Synthesized PmAP silver nanocomposite showed the highest DC‐conductivity of 1.03 × 10^?6 S/cm. From the above characterizations, it can be said that silver nanoparticle shows some doping effect on the conductivity of PmAP. The doping level of the silver nanoparticle inside the polymer was optimized in terms of DC‐conductivity of the silver nanoparticle‐doped PmAP film. Copyright © 2009 John Wiley & Sons, Ltd.     

Fabrication and characterization of nylon 6/foliated graphite electrically conducting nanocomposite

In this study, the nylon 6/foliated graphite (FG) electrically conducting nanocomposites with a low percolation threshold of less than 0.75 vol % have been prepared via an in situ polymerization approach in the presence of FG nanosheet filler. Based on laser counting, scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction characterization techniques, the structures and morphologies of the nanoscale filling particles and the resulting nanocomposites were examined. Using percolation theory, the conductivity behavior of the nanocomposite samples were modeled and analyzed. Through the use of mean‐field and excluded volume approaches, it was demonstrated that the experimentally observed percolation threshold values could be approximately estimated, and a correlation between the percolation threshold and the aspect ratio of FG particles could be quasi‐quantitatively established. Also, preliminary studies on the effects of FG nanosheets on the thermal properties of the host nylon 6 were performed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2844–2856, 2004     

Synthesis of a hexafluoropropylidene-bis(phthalic anhydride)-based polyimide and its conducting polymer composites with polypyrrole

A new electrically conducting composite film from polypyrrole and 4,4′-(hexafluoroisopropylidene)-bis(phthalic anhydride)-based polyimide was prepared. Pyrrole and the dopant ion can easily penetrate through the polyimide substrate and electropolymerize on the platinum (Pt) electrode due to the swelling of the polyimide on the metal electrode. The electrochemical properties of polypyrrole-polyimide (PPy/PI) composite films have been investigated by using cyclic voltammetry. The PPy/PI composite film is suitable for use as the electroactive material owing to its stable and controllable electrochemical properties. The electrical conductivity of composites falls in the range 0.0035–15 S/cm. Scanning electron micrograph, FTIR, and thermal studies indicate that PPy and PI form a homogeneous material rather than a simple mixture. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3009–3016, 1997     

Properties of a nanocomposite polymer electrolyte from an amorphous comb-branch polymer and nanoparticles

Three fully amorphous comb-branch polymers based on poly(styrene-co-maleic anhydride) as a backbone and poly(ethylene glycol) methyl ether of different molecular weights as side chains were synthesized. SiO₂ nanoparticles of various contents and the salt LiCF₃SO₃ were added to these comb-branch polymers to obtain nanocomposite polymer electrolytes. The thermal and transport properties of the samples have been characterized. The maximum conductivity of 2.8×10^–4 S cm^–1 is obtained at 28 °C. In the system the longer side chain of the comb-branch polymer electrolyte increases in ionic conductivity after the addition of nanoparticles. To account for the role of the ceramic fillers in the nanocomposite polymer electrolyte, a model based on a fully amorphous comb-branch polymer matrix in enhancing transport properties of Li⁺ ions is proposed.     

Synthesis of functionalized conducting polymer “polyanthranilic acid” using various oxidizing agents and formation of composites with PVC

Synthesis of carboxyl functionalized polyaniline (PANI) (polyanthranilic acid PANA) is reported based on our recent studies using various oxidizing agents. PANA was synthesized in acidic medium using ammonium peroxodisulfate, hydrogen peroxide, and potassium permanganate as oxidizing agents and their structural, electrochemical, and electrical properties are studied. A comparative study among the polymers formed by various oxidizing agents and also with PANI is made. Various possible oxidation states of PANA are discussed, with the help of electrochemical data. A composite of PANA and polyvinyl chloride (PVC) containing 20% PVC by weight is synthesized and used for the development of solid state pH electrode. The composite was synthesized to improve mechanical strength, stability, and restrict solubility. The pH sensor response is found to be reversible and linear in the pH range 1–7. PANA and PVC (20 wt%) based pH sensors show potential applications in development of pH transducers based sensors/biosensors. Copyright © 2010 John Wiley & Sons, Ltd.     

Sulfonic acid-based metal organic framework functionalized magnetic nanocomposite combined with gas chromatography-electron capture detector for extraction and determination of organochlorine

The metal organic framework functionalized with sulfonic acid was combined with magnetic nanoparticles to fabricate a new nanocomposite (denoted as Fe₃O₄@PDA@Zr-SO₃H). By combining with gas chromatography-electron capture detector, the resulting Fe₃O₄@PDA@Zr-SO₃H nanocomposite was successfully used as a high-efficiency adsorbent for pre-concentrating eight organochlorine pesticides from water sample in environment. Apart from the ability of fast separation, the as-prepared Fe₃O₄@PDA@Zr-SO₃H nanocomposite also exhibited high adsorption capacity for organochlorine pesticides. With the use of optimal experimental conditions, the linear relationship can be obtained in the range of 0.05∼300 μg/L, the correlation coefficient was over 0.9978, and the relative standard deviation was located in 2.5%–7.7%. Moreover, the limit of detection and quantification was between 0.005–0.016 μg/L and 0.017∼0.050 μg/L. Finally, the nanocomposite was used for the determination of organochlorine pesticides from environmental water samples, and displayed the recovery of 82%–118%.     

Determination of percent composition of a mixture analyzed by gas chromatography. Comparison of a helium pulsed-discharge photoionization detector with a flame ionization detector

We present the results of a study of percent composition for a mixture which has been separated by gas chromatography and analyzed using helium pulsed-discharge photoionization detection (He-PDPID) and flame ionization detection (FID). FID has long been the means by which the percent composition of a hydrocarbon mixture has been determined since it has been previously established as a "carbon counting device". However, in this study we present results which show that He-PDPID is more accurate in determining the percent composition of a hydrocarbon mixture and, because it is a universal detection method and can detect compounds that FID cannot, it is also more effective for determining the percent composition of mixtures containing organic compounds with a variety of other functional groups.     

供气相色谱仪使用的热导检测器的设计与实现

为了提高气相色谱仪用热导检测器的性能,设计了热导检测器的精密恒流源和差压检测电路。恒流源由场效应管IRF460、运算放大器AD8672和线性光耦HCNR201构成,低噪声电桥差压检测电路由2片AD8597构成。建立了差压检测电路的噪声模型,计算了噪声理论值。实际测试结果表明,该热导检测器的基线噪声达到4 μV, 50 min的基线漂移为15 μV,恒流源波动接近1 μA,优于现有热导检测器的技术指标。所介绍的设计方案和噪声分析方法对热导检测器的电路设计有较大的参考价值。     

Design and construction of three-dimensional graphene/conducting polymer for supercapacitors

Three-dimensional graphene/conducting polymer(3DGCP) composites have received significant attention in recent years due to their unique structures and promising applications in energy storage.With the structural diversity of graphene and π-functional conducting polymers via rich chemical routes,a number of 3DGCP composites with novel structures and attractive performance have been developed.Particularly,the hierarchical porosity,the interactions between graphene and conducting polymers as well as the their synergetic effects within 3DGCP composites can be well combined and elaborated by various synthetic methods,which made 3DGCP composites show unique electrochemical properties and significantly improved performance in energy storage fields compared to other graphenebased composites.In this short review,we present recent advances in 3DGCP composites in developing effective strategies to prepare 3DGCP composites and exploring them as a unique platform for supercapacitors with unprecedented performance.The challenges and future opportunities are also discussed for promotion of further study.     

Photopolymerized silver-containing conducting polymer films. Part II. Physico-chemical characterization and mechanism of photopolymerization process

Physico-chemical and mechanical characterizations of nanophase silver-containing polypyrrole films prepared using a new photopolymerization process were performed. In general, the recorded physical, chemical, and mechanical data characteristic of these films was similar to corresponding literature data obtained from electropolymerized or chemically polymerized polypyrrole. However, photopolymerized polypyrrole films possessed an unusually high anion-to-monomer ratio of 0.8:1. Also, the photopolymerized material contained silver nanoparticles, having diameters of 2 μm or less, uniformally distributed throughout the polymer matrix. While the photopolymerization mechanism is complex, it is suggested that a pyrrole–silver cation complex is most likely the key component involved in the photopolymerization initiation step. Paper submitted for inclusion in the special issue of the Journal of Solid State Electrochemistry honoring the 85th birthday of Professor John O’M. Bockris.     

Assembly and decomposition of building blocks to analyze polymer NEXAFS spectra

The poly(ethylene-terephthalate) and poly(bisphenol-A-carbonate) compounds are used to illustrate the possibilities and limitations of building-block analysis of polymer near-edge X-ray absorption spectra. Experimental spectra obtained for thin polymer films are analyzed using theoretical static exchange calculations of C_1s and O_1s excitation spectra on model molecules selected as possible building blocks. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 749–765, 1997     

Construction of a TiO2–Fe3O4‐decorated molecularly imprinted polymer nanocomposite for tartrazine degradation: Response surface methodology modeling and optimization

We synthesized a novel recoverable and reusable photocatalyst system for tartrazine degradation by one‐step incorporation of Fe₃O₄ and TiO₂ nanoparticles into a molecularly imprinted polymer through a facile precipitation polymerization method. The as‐prepared samples were systematically characterized using X‐ray diffraction, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, energy‐dispersive spectroscopy, and vibrating sample magnetometry. Benefiting from the positive synergistic effect, tartrazine was almost completely degraded under UV‐C within 180 min by the multicomponent photocatalyst (Fe₃O₄ + TiO₂ + MIP) in comparison with far fewer activities by the corresponding NIP system and the nonmagnetic and bare structures. On the other hand, the central composite design in response surface methodology was applied to optimize the tartrazine photocatalytic degradation process. Twenty experiments were conducted by adjusting three parameters (nanocomposite dosage, initial pH of the reaction solution, and initial dye concentration) in the multiple variable analysis method. A satisfactory correlation between the experimental and predicted values was obtained (R² = 0.956). Additionally, ANOVA analysis with a p value of 1.15 × 10^–5 indicated that the model terms are highly significant. Under the determined optimum conditions, a verification experiment was conducted and shown the adequately approximate value between the predicted (99%) and the experimental (97%) results, which confirmed the validity of the model.     

Stopped-flow kinetic determination of a binary mixture: Simultaneous determination of europium and cerium

A kinetic method is proposed for the simultaneous determination of europium(II) and cerium(III), based on their inductive action on the Cr(VI)-iodide redox reaction in weak acidic medium. The reaction rate was followed by the stopped-flow spectrophotometric technique using starch-iodine complex as indicator. The method can be used for the determination of europium and cerium after reduction with zinc metal powder in the concentration ranges 0–2.1 and 0–1.8 g/ml, respectively. The detection limits are 0.015 g/ml Eu and 0.010 g/ml Ce. 100 to 1000 times higher concentrations of other rare earth metal ions and Th⁴⁺, Al³⁺, Mn²⁺, Hg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Pb²⁺ do not interfere. The method is applied to the determination of europium and cerium in a synthetic sample and in barium yttrium fluoride fluorescent material, with relative standard deviation of about 4%.     

Highly sensitive determination of haloperidol in human serum by capillary gas chromatography using a surface ionization detector

A method has been developed for highly sensitive determination of haloperidol in human serum involving a simple extraction procedure followed by gas chromatographic separation. Target components were separated from the extracting solvents with a Van den Berg type solventless sample injector before introduction Into a DB-1 capillary separation column. A surface ionization detector (SID), which has highly selective sensitivity for Substituted amines, was employed for quantitation using bromperidol as an internal standard. Chloroform proved to be the best extracting solvent, yielding a quantitative detection limit of 5 ng/ml (S/N = 2). Comparison of the response to target compounds obtained by the SID, FTD (flame thermionic detector), and FID (flame ionization detector) showed the SID to be superior.     

Permeation of binary gas mixture through glassy polymer membranes with concentration-dependent diffusivities

An analytical solution has been obtained for the modified dual-mode mobility model for a single gas proposed by Zhou and Stern and extended to a binary gas mixture to describe the pressure dependence of mean permeability coefficients for CO₂ and CH₄ mixtures in homogeneous cellulose triacetate membranes. The permeabilities calculated from the model fitted the corresponding experimental results quite well. Permeation experiments for equimolar CO₂ and CH₄ mixture in a homogeneous membrane of methyl methacrylate and n-sbutyl acrylate copolymer were performed along with sorption experiments for pure CO₂ and CH₄ to test the applicability of the model. The experimental permeabilities were close to those calculated from the model.     

Synthesis and characterization of a new benzobisoxazole/thiophene derivative polymer and the effect of the substituent on the push/pull properties

Conducting polymer synthesis of a new benzobisoxazole/thiophene derivative is reported. The conjugated co-polymer presents the lowest bandgap (1.78 eV) reported for a neutral benzobisoxazole/thiophene polymer. Electrochemical polymerization is carried out by cyclic voltammetry, and the new conducting polymer is characterized by Raman spectroscopy and X-ray photoelectron spectroscopy. The results indicate that the coupling of the monomer unit occurs at the 2,2′ positions of the thiophene ring. Theoretical studies in derivatives of this family of compounds are conducted to validate the effect on the bandgap modulation due to the change in the substituent on the phenyl moiety of the monomer. The comparison between experimental and theoretical properties shows the substituents impact on the optical properties of the system, and its viability to be used in sensors.     

Biomolecular hybrid of a conducting polymer with DNA: morphology, structure, and doping behavior

A poly(o-methoxyaniline) (POMA)/DNA [weight fraction of DNA (W(DNA)) = 0.45] hybrid was prepared by mixing their solutions in sterilized double distilled water. The solution turned green upon aging for a longer time, and the doping of POMA by DNA was complete after about 15 d of aging. The doping was confirmed from the UV-vis spectra where the 599 nm peak of POMA(EB) disappeared and a new peak for a pi to localized polaron band-transition appeared. With increasing aging time the new peak gradually shifted from 674 nm at 3 h to 820 nm at 15 d of mixing and thereafter it remained constant. The absence of a free carrier tail in the UV-vis spectra indicated a coiled structure of POMA in the complex. Circular dichroism spectra of the hybrid solution indicated that the DNA conformation (double helical structure) remained unchanged in the hybrid. The SEM micrograph of the freeze-dried hybrid showed a needle-like morphology of the DNA dispersed in a polymer matrix and it was completely different from the fibrillar network morphology of pure DNA in the solid state. The TEM micrograph indicated a homogeneous dispersion of DNA fibrils in the POMA matrix. The melting temperature of the POMA-DNA hybrid showed an increase compared to that of pure DNA by 5 degrees C, probably caused by an electrostatic interaction between the DNA anion and the POMA radical cation generated in the doping process. WAXS investigations revealed that the DNA crystal structure remained unchanged in the hybrid whereas the POMA crystal structure might be lost. An FT-IR study suggested that interaction occurred between the phosphoric acid group of DNA and a nitrogen atom of POMA through proton transfer from the OH group of the former. A schematic model of the POMA-DNA complex randomly anchoring POMA chains with the DNA molecule was proposed. The dc conductivity of the POMA-DNA complex was found to be ca. 10(-7) S . cm(-1). Hence, this work describes a procedure for making a DNA-conducting polymer hybrid without changing the conformation and structure of DNA. [Diagram: see text]     

Porous nanocomposite hydrogel of vinyled montmorillonite-crosslinked maltodextrin-co-dimethylacrylamide as a highly stable polymer carrier for controlled release systems

Nanocomposite hydrogel consisting of dispersed montmorillonite-crosslinked maltodextrin-co-dimethylacrylamide (malt-dex-co-DMAAm) as a highly stable device was developed. Carbon-carbon π-bonds issued from glycidyl methacrylate (GMA) were incorporated onto both the MMT (MMT-π) and the malt-dex (malt-dex-π) structures. The nanocomposite copolymer hydrogel was processed via radical crosslinking reaction of malt-dex-π with MMT-π in the presence of DMAAm. The radical reaction of the carbon-carbon π-bonds at the MMT-π was verified by treating the MMT-π with sodium persulfate. There was an excellent dispersion of the MMT-π at the interior of the matrix even after the nanocomposite hydrogel being swollen, demonstrating that the developed methodology can imprint stability of mineral nanoparticles into a porous polymer network preventing diffusion of water-bonded silicate platelets toward the outside matrix. The water absorption profile became more dependent on the polymer relaxation for mineral-loader nanocomposite hydrogels. Higher water absorption had an impact on reduction of elasticity modulus due to softer polymer network in swollen state.