Interfacial synthesis of polypyrrole/graphene composites and investigation of their optical,electrical and electrochemical properties

We report the development of a novel route for the synthesis of polypyrrole/graphene (PPy/GR) composites by liquid ? liquid interfacial polymerization, where GR and the initiator were dispersed in the aqueous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, X‐ray diffraction, thermogravimetric analysis, electrochemical and electrical conductivity measurements. Structural analysis reveals a uniform dispersion of GR sheets in the PPy matrix. The composites showed noticeable improvement in thermal stability and electrical conductivity (8.45 S cm^?1) and excellent electrochemical reversibility in comparison with pure PPy. A specific capacitance of 260 F g^?1 at a current density of 100 mA g^?1 was achieved for the composite during the charge–discharge process. © 2013 Society of Chemical Industry     

分级多孔聚吡咯膜的界面自组装合成与电化学电容性

通过界面自组装聚合,在长链表面活性剂OP10的辅助下成功制备了分级多孔结构聚吡咯膜。对所得聚吡咯的分子结构、微观形貌和电化学性能分别进行了表征和研究。结果表明：界面聚合中引入OP10对聚吡咯的分子结构并没有影响,但对其微观形貌却具有重要作用。当OP10的用量优化为0.02 g时,聚吡咯可自组装形成分级多孔结构,既有纳米孔（约100 nm）,也有亚微米孔（200~1000 nm）和微米孔（1~3.5 μm）。由于相对较高的活性表面积和总孔体积,分级多孔聚吡咯作为电极材料最大比电容可达357 F·g^-1,比相同条件下传统界面法制备的聚吡咯高70%以上。此外,2000次充放电循环后该材料仍保持初始比电容的87.6%,表明其优异的循环稳定性。     

Fabrication of polypyrrole/graphene oxide nanocomposites by liquid/liquid interfacial polymerization and evaluation of their optical,electrical and electrochemical properties

A novel route has been developed to synthesize polypyrrole (PPy)/graphene oxide (GO) nanocomposites via liquid/liquid interfacial polymerization where GO and initiator was dispersed in the aquous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), ultraviolet–visible absorption (UV–vis), X-ray diffraction (XRD), electrochemical and electrical conductivity measurements. A good dispersion of the GO sheets within the PPy matrix was observed from the morphological analysis. The composites exhibited noticeable improvement in thermal stability and electrical conductivity in comparison to pure polypyrrole. The composites showed excellent electrochemical reversibility at the scan rate of 0.1 V/s and good cyclic stability even up to 100th cycle. Newly developed graphene oxide based polypyrrole composite could be applied in electrochemical energy storage device.     

Study of the anticorrosive properties of polypyrrole/polyaniline bilayer via electrochemical techniques

In this work, using electrochemical techniques the authors investigated the protective properties of a polypyrrole/polyaniline bilayer as a conductive polymer. A polypyrrole/polyaniline bilayer was deposited on carbon steel substrate by potentiostatic method. The electric capacitance and resistance of the films were monitored with the immersion time in a corrosive solution to investigate the water permeability of the films. Polypyrrole/polyaniline bilayer has a relatively low permeability and good catalytic behavior in passivation of carbon steel in longer periods. The results show that the bilayer has a better anticorrosive behavior compared to homopolymers (polypyrrole and polyaniline).     

Interfacial polymerization of pyrrole and in situ synthesis of polypyrrole/silver nanocomposites

We present a new synthetic approach leading to the formation of polypyrrole architectures in submicron level and to silver/polypyrrole nanocomposites via an interfacial polymerization in a water/chloroform interface. The oxidizing agent was either Ag(I) or Fe(III). In the first case, silver nanoparticles resulted. The mean diameter of the polypyrrole structures is in the range of 200-300 nm according to the addition or not of various surfactants. The progress of the reaction was studied by UV-visible spectroscopy, which also revealed the formation of a polaron band during the growth of the oligomers. The crystal structure of the polymers was examined by X ray diffractometry and all samples appeared to be amorphous, while the samples were further characterized by thermogravimetric analysis and FT-IR spectroscopy.     

Self‐assembled polypyrrole film by interfacial polymerization for supercapacitor applications

A facile interfacial synthesis strategy is proposed to synthesize self‐assembled polypyrrole (PPy) free‐standing films for electrochemical capacitors with the assistance of surfactants. The chemical structure of the obtained samples is characterized by Fourier transform infrared. The morphologies of the samples are studied by scanning electron microscope. The results show that the prepared PPy films own highly porous structures using Tween80 as a surfactant, while the synthesized PPy films have vesicular structures by adding Span80 as a surfactant. Furthermore, lowering polymerization temperature makes PPy films have smaller and more pores or vesicles. The PPy films prepared at 0°C with Tween80 as a surfactant possess a high specific capacitance of 261 F g^?1 at 25 mV s^?1 as well as retain 75% of the initial specific capacitance value after 1000 cycles. The good electrochemical properties can be attributed to the highly porous structural advantage of the PPy films caused by Tween80. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41615.     

Electrosynthesis and capacitive performance of polyaniline–polypyrrole composite

The composite of polyaniline and polypyrrole (PPY‐PANI) was prepared by two‐step electrochemical polymerization method. Techniques of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravity analysis (TG/DTG) measurements were used to characterize the morphology and structure of the composite. The electrochemical properties of the composite were investigated by cyclic voltammetry (CV), galvanostatic charge‐discharge, and electrochemical impedance spectroscopy (EIS). The results indicated that the polyaniline–polypyrrole composite showed better electrochemical capacitive performance than polypyrrole (PPY) and polyaniline (PANI). The specific capacitance of the composite electrode was 523 F/g at a current of 6 mA/cm² in 0.5 M H₂SO₄ electrolyte. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Preparation of polyaniline/nickel oxide nanocomposites by liquid/liquid interfacial polymerization and evaluation of their electrical,electrochemical and magnetic properties

A novel route has been developed to synthesize polyaniline (PANI)/nickel oxide (NiO) nanocomposites via liquid/liquid interfacial polymerization where NiO and the initiator were dispersed in the aqueous phase and the monomer was dissolved in the organic phase. The synthesized samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet?visible absorption, X‐ray diffraction, and electrochemical, electrical conductivity and magnetic property measurements. NiO was dispersed uniformly within the PANI matrix. The composites exhibited noticeable improvement in thermal stability and electrical conductivity in comparison with pure PANI. The composites showed excellent electrochemical reversibility at a scan rate of 0.1 V s^?1 and good redox stability even up to 100 cycles. The room temperature magnetic hysteresis measurements show a low value of coercivity for the polymer composites in comparison with NiO. The remnant magnetization (M_r) values were found to be increased with increasing concentration of NiO in the composites. © 2013 Society of Chemical Industry     

Dielectric and electrical conduction behavior of carbon paste electrochemical electrodes,with decoupling of carbon,electrolyte and interface contributions

The electrical conduction and dielectric (capacitive) properties of electrolyte-filled carbon paste electrochemical electrodes are reported, with the carbon, electrolyte (15% H₂SO₄), carbon–electrolyte interface and carbon–contact(metal) interface contributions fully decoupled for the first time. Without full decoupling and with the carbon contributions neglected, the carbon–electrolyte specific interfacial capacitance would be much over-estimated and the carbon–electrolyte interfacial resistivity would be much under-estimated. The carbons and electrolyte are comparable in both dielectric constant and resistivity. The specific contact capacitance is increased and the contact resistivity is decreased by adding the electrolyte to a carbon. The electrolyte is more effective than water in enhancing carbon–liquid and paste–contact interfaces. Conductivity is attractive for batteries and supercapacitors; strong dielectric properties are attractive for supercapacitors but not batteries. Exfoliated graphite provides handleability and excellent volumetric and interfacial conductivities. It gives low carbon dielectric constant, but contributes to the interfacial capacitances. Activated graphite nanoplatelet (GNP) gives high carbon and paste dielectric constants and high specific contact capacitance. Activated carbon gives poor volumetric and interfacial conductivities. Exfoliated graphite is even better than carbon black for batteries; GNP is even better than activated carbon for supercapacitors; an exfoliated-graphite/GNP mixture is suitable for both; natural graphite is not competitive for either.     

Aqueous/ionic liquid interfacial polymerization for preparing polyaniline nanoparticles

The interfacial polymerization of aniline at aqueous/IL has been conducted. The product was characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy, thermal gravimetric analysis (GTA), and electrical conductivity measurement. In this route, both solvents used are environmentally benign and polyaniline (PANI) particles with diameters from about 30-80 nm can be fabricated. We believe that this method can be used to synthesize some other useful polymers.     

3D Printing/Interfacial Polymerization Coupling for the Fabrication of Conductive Hydrogel

In this study, 3D printing is coupled with interfacial polymerization to obtain electroactive hydrogels with complex and defined geometry. Conductive hydrogels are created through a two‐step procedure: first a digital light processing 3D printing system is used to fabricate poly(ethylene glycol)diacrylate 3D structure and then pyrrole is oxidized to polypyrrole (PPY), exploiting an interfacial polymerization mechanism through which PPY can be formed in the poly(ethylene glycol) matrix, thus creating a conductive phase.     

Core–Shell Structured Cellulose Nanofibers/Graphene@Polypyrrole Microfibers for All‐Solid‐State Wearable Supercapacitors with Enhanced Electrochemical Performance

Thanks to their considerable electrochemical and mechanical properties, fiber‐shaped supercapacitors have become the most potential energy storage devices for portable and wearable electronics in the future; however, challenges still exist in the pursuit of practical applications among them. In this work, ternary microfibers, which are composed of TEMPO‐oxidized cellulose nanofibers/reduced graphene oxide microfiber cores coated with polypyrrole shell layers, are successfully fabricated through industrializable and sustainable wet‐spinning and interfacial polymerization strategies. The prepared microfibers possess well‐defined microstructures and outstanding mechanical properties (559 MPa). When assembled into symmetrical all‐solid‐state fiber‐shaped supercapacitors (FSCs), they exhibit remarkable electrochemical properties (647 mF cm^?2, 14.37 µWh cm^?2 at 0.1 mA cm^?2), prominent cycling stability (92.5% capacitance retention and 92.6% coulomb efficiency after 10 000 cycles), and extraordinary flexibility (no significant decay in capacitance after 5000 bending cycles), which are superior to all the congeneric FSCs reported to date. The prominent performances are ascribed to the synergistic effect of the well‐designed ternary system and synergistic effects between interior components. The advantages in electrochemical, mechanical, and industrial properties of the ternary FSCs can provide reference and boost the development of flexible energy storage applications.     

Potentiostatically deposited polypyrrole/graphene decorated nano-manganese oxide ternary film for supercapacitors

A simple method based on potentiostatic polymerization was developed for the preparation of ternary manganese oxide-based nanocomposite films. The ternary nanocomposites, which were characterized using x-ray diffraction spectroscopy and x-ray photoelectron spectroscopy, showed that the manganese oxide within the film consisted of MnO₂ and Mn₂O₃. Electrochemical measurements showed that the ternary nanocomposite electrode exhibited high specific capacitance (up to 320.6 F/g), which was attributed to the morphology of a polypyrrole/graphene/manganese-oxide (PPy/GR/MnO_x) ternary nanocomposite. The experimental approach maximized the pseudocapacitive contribution from redox-active manganese oxide (MnO_x) and polypyrrole (PPy), as well as the electrochemical double layer capacitive (EDLC) characteristic from graphene (GR) sheets. Long cyclic measurements indicated that the specific capacitance of the ternary nanocomposite film could retain 93% of its initial value over 1000 charge/discharge cycles, in the potential range of −0.2 to 0.7 V versus silver/silver chloride electrode (Ag/AgCl).     

聚苯胺/活性炭复合材料的共价键构筑及电容性能

导电聚苯胺(PANI)与活性炭(AC)构筑复合电极材料是当前制备高性能超级电容器电极材料的热点研究方向。其关键点之一是制备出炭与PANI两种材料均匀分散、且具有相当牢固强度连接界面的复合材料。为此,以AC为基材,对其进行功能化处理后,将苯胺在其表面原位聚合,获得具有界面共价键连接的PANI/AC复合材料(PANI–c–AC)复合材料。通过扫描电子显微镜、元素分析、傅里叶变换红外光谱、X射线衍射仪及电化学工作站等测试并研究其结构与电容性能。结果表明,具有界面共价键连接的PANI–c–AC复合材料比电容值(393.3 F/g)最高,既优于单一AC(111.8 F/g)与PANI(296.2 F/g),也优于无共价键连接的PANI–AC复合材料(360.5 F/g)。     

Electrochemical polymerization of pyrrole in supercritical carbon dioxide-in-water emulsion

Supercritical carbon dioxide is an environmentally benign solvent but its low polarity limits electrochemical reactions in it. We now report the electrochemical polymerization of pyrrole in a supercritical carbon dioxide-in-water (C/W) emulsion in the presence of a surfactant. Black polypyrrole films were formed on Pt electrodes, whose conductivity was comparable with non-oriented polypyrrole prepared in conventional solvents. The structure of the polypyrrole films was confirmed by IR and Raman spectroscopic measurements. p-Toluenesulfonic acid was a suitable supporting electrolyte among the electrolytes examined for the electrochemical polymerization in the C/W emulsion. A typical nodular morphology was observed on the basis of the SEM and AFM measurements. Confocal scanning microscope revealed the formation of a fine uneven texture on the film prepared in the C/W emulsion.     

Performance of electrolysis with two-phase electrolyte. The trickle electrode for the electrochemical conversion of substances with low solubility in aqueous electrolytes with special respect to electrochemical extraction processes

The electrochemical conversion of organic substances with low solubility in water which yield ionic products can be performed in aqueous electrolytes, as the main medium for the ionic charge transfer, by dissolving the organic depolariser in a nonaqueous solvent and conducting the electrolysis at the organic solvent-electrode interface. Polarity of this second phase, as well as good contact between organic phase and working electrode are essential. The anodic oxidation of ferrocene dissolved in organic solvents (preferentially methylene chloride) to ferricinium salts was chosen as a model system to study the conditions of this type of two-phase electrolyte electrolysis. Experiments with single CH₂Cl₂-droplets on smooth nickel anodes covered by an aqueous electrolyte show that the most important parameters which govern the anodic conversion of ferrocene are: (a) electrical conductivity supplied to the organic phase by the anodically-produced ferricinium salt; (b) small difference in surface tensions at the electrode-organic phase interface and the electrode-aqueous phase interface; and (c) direction and magnitude of the Galvani potential difference at the aqueous-organic interface. Quantitative studies on the influence of the different parameters were performed at a well-defined and stationary three-phase boundary. The results were used for the construction of a trickle cell with particulated horizontal working electrodes (nets, perforated plates etc.) which offers the possibility for continuous processing of two-phase liquid-liquid electrolytes. Such electrodes show excellent mass and charge transfer characteristics and can be used for simultaneous electrochemical conversion of a neutral depolariser and extraction of its ionic conversion-product out of the organic solvent into the aqueous electrolyte (electrochemical extraction).     

The effects of the temperature on the some parameters obtained from current-voltage and capacitance-voltage characteristics of polypyrrole/n-Si structure

The polypyrrole/n-Si structure has been directly formed onto the n-Si substrate by the electrochemical polimerization of the organic polypyrrole at 45 °C electrolyte temperature. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the structure have been determined at various temperatures in the range of 77-300 K and different frequencies. Some diode parameters have been calculated from these curves. It has been seen that the measured capacitance decreases with increasing frequency due to a continuous distribution of the interface states in the frequency range of 10 kHz-1 MHz. The barrier heights values obtained from the I-V and C-V characteristics have been compared. It has been seen that the barrier height value obtained from the C-V measurements are higher than that obtained from the I-V measurements at various temperatures. This behaviour has been attributed to the interfacial layer, the interface states and barrier inhomogeneity of the structure. Also this discrepancy can be due to the different nature of the C-V and I-V measurement techniques. A correlation seems to exist between the variation of the band gap and Fermi level energy of Si with temperature.     

Electrochemical inspection of polypyrrole/chitosan/zinc oxide hybrid composites

Polymer nanocomposite composed of polypyrrole, chitosan, and zinc oxide nanoparticles has been synthesized and it has been evaluated for various electrochemical aspects of the current electrochemical industry. The polypyrrole (PPy) was synthesized by the chemical oxidative polymerization reaction by employing ammonium persulfate as oxidizing agent. Composites of polypyrrole/chitosan (PPy/Chy) and polypyrrole/chitosan/ZnO (PCZ) composites were synthesized by the solution blending method. Detailed structural, morphological, thermal characterization of PPy, PPy/Chy, and PCZ were performed to characterize the specific features of the systems. The composites exhibit better thermal stability and high surface area and the addition of ZnO nanoparticle increase the crystallinity of the composite. Electrochemical characterization of the ITO electrodes modified with PPy, PPy/Chy, and PCZ were performed using cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry techniques. The present study highlights the role of a bio-compatible material with high surface area and conductive constituent for designing of various high performing electronic noninvasive sensors, biosensors, and so forth.     

COMPARISON BETWEEN THREE-PHASE EXTRACTION SYSTEM OF TBP-KEROSENE/HClO4-H2O AND TWO-PHASE EXTRACTION SYSTEM OF TBP/HC104-H2O *

ABSTRACT

Three-phase extraction system of TBP-kerosene / HClO₄-H₂O has been studied and compared with two-phase system of TBP / HClO₄-H₂O. The results indicate that the composition of the middle phase and its change with the increasing aqueous acidity in the three-phase system are almost the same as that of the organic phase in two-phase system. The extraction in high acidity can be explained by the solubilization of acid and water in the aggregates formed by amphiphilic extracted complexes.     

Focused ion beam processing for transmission electron microscopy of composite/adhesive interfaces

Although most transmission electron microscope (TEM) investigations were carried out using conventional ultramicrotomy, they were limited to the tooth/adhesive resin interface and were difficult to accomplish for the resin-composite interface. Some of these limitations have been overcome with the introduction of focused ion beam (FIB) milling. Therefore, the objective of the study was to compare different composites/adhesive interfaces using FIB/TEM technique. Cylindrical cavities were prepared in extracted human molar teeth. The restored cavities were divided into four groups: (1) One-step self-etch Scotchbond Universal (SBU; 3M ESPE, USA), (2) all-in-one Xeno-V⁺ adhesive (X5P; DENTSPLY, Germany), (3) two-step etch-and-rinse Prime and Bond NT (PNT; DENTSPLY, Germany) that were restored with Filtek Supreme Ultra Universal composite (3M ESPE, USA), and (4) teeth restored with the two-step self-etch Filtek Silorane adhesive (SSA; 3M ESPE, USA) that were restored with its corresponding Filtek Silorane composite (3M ESPE, USA). All specimens were cross-sectioned and subjected to FIB preparation followed by composite/adhesive interfacial TEM examination. The TEM findings were variable and ranged from concentrated clusters of nanoparticles to phase separation of adhesive components and large osmotic blisters. The osmotic blisters in all-in-one adhesives appeared to be influenced by the presence of water and the solvent’s vapor pressure in the cavity. In conclusion, FIB/TEM is a powerful tool allowing the study of biomaterials interaction in situ. The absence of residual water in the adhesives may reduce osmotic blistering that, in turn, may improve the reactivity of the resin monomers, as well as interfacial bonding.