超临界二氧化碳流体环境中导电聚吡咯复合材料的制备

以聚苯乙烯(PS)和锌盐中和的磺化聚苯乙烯(Zn-SPS)膜为基体, 在超临界二氧化碳(SC-CO₂)环境中用化学氧化法原位制备了聚吡咯(PPy)导电复合材料. 由于SC-CO₂对聚合物基体的强溶胀作用, 吡咯分子高效地扩散到基体内部进行聚合而形成导电通路, 得到比传统的水溶液法更高的电导率. 聚合物基体的性质对复合材料的导电性和形貌产生重要影响. 在相同条件下, Zn-SPS/PPy的电导率比PS/PPy高3~4个数量级, 而它们的体积逾渗阈值分别为2.7%和6.2%, 远远低于理论预测值(16%).     

Synthesis of electrically conductive polypyrrole-polystyrene composites using supercritical carbon dioxide: I. Effects of the blending conditions

The electrical conductivity for a polymer composite consisting of polypyrrole (PPy) and an insulating host polystyrene (PS) is reported in this study. The host polymer was blended with pyrrole monomer using either supercritical carbon dioxide (SCCO₂) or high-pressure liquid carbon dioxide (HPLCO₂) as the carrying solvent. After the blending process, the blended host polymer was soaked in an oxidant solution. This process is compared with that of oxidant impregnation. With the same processing conditions, a polymer composite with much higher conductivity was obtained when the blending process was carried out before doping in an oxidant agent. Scanning electron microscope (SEM) and elemental analysis reveal that polymerization proceeded when the blended host polymer was soaking in the oxidant solution. It is observed that SCCO₂ provides better conditions for blending the host polymer with pyrrole monomer than HPLCO₂ at the same density. The maximum conductivity of the polymer composites also increases with temperature and pressure at the same SCCO₂ density.     

The development of conductive composite surfaces by a diffusion-limited in situ polymerization of pyrrole in sulfonated polystyrene ionomers

Electrically conductive composite surfaces were prepared by a diffusion-controlled in situ polymerization of pyrrole in the surface layer of sulfonated polystyrene ionomer films. Premolded films of the ionomer sulfonic acid derivatives were sequentially immersed in aqueous solutions of pyrrole and FeCl₃, and polymerization occurred only where both the monomer and the oxidant were present. The penetration of the polypyrrole (PPy) into the film was controlled by varying the immersion time in the monomer solution. The amount of PPy produced depended on the immersion time of the film in the monomer and the degree of sulfonation of the ionomer. Surface conductivities of 10⁻⁴-10⁻¹ S/cm were achieved with PPy concentrations from 2 to 22 wt % and composite layers as thin as 15 μm. Intermolecular interactions occurred between PPy and the ionomer by proton transfer. Incorporation of PPy also increased the tensile strength of the ionomer film, significantly increased its modulus above T_g, and inhibited melt flow. © 1997 John Wiley & Sons, Inc.     

纳米石墨薄片/聚吡咯复合材料的制备及导电性能

膨胀石墨经过超声处理制备了纳米石墨薄片。以其为导电填料，对甲苯磺酸为掺杂剂，FeCl₃·6H₂O为氧化剂，引发吡咯单体发生原位聚合，制备出纳米石墨薄片/聚吡咯(NanoGs/PPy)复合材料。利用红外光谱(FTIR)、扫描电镜(SEM)和透射电镜(TEM)表征了材料的组成和结构。结果表明，石墨薄片被聚吡咯完全包覆；并且以纳米级尺寸分散在聚吡咯基体中。热失重(TG)分析和电导率测试结果表明，复合材料的耐热性能和导电性能较纯聚吡咯有所提高。     

Synthesis of electrically conductive polypyrrole-polystyrene composites using supercritical carbon dioxide: II. Effects of the doping conditions

A polymer composite of polypyrrole (PPy) and polystyrene (PS) was synthesized in this study. Pyrrole was firstly impregnated within the PS substrate where supercritical carbon dioxide (SCCO₂) at 40 °C and 10.5 MPa was used as the solvent. The resulting polymer composite was then soaked in a solution of metallic salt to form an electrically conductive product. Thermal analyses were carried out in this study. Glass transition temperatures from the DSC curves and thermal decomposition temperatures from the TGA curves were observed. These temperatures rise gradually from pure PS, undoped blend to doped composite that indicates blending took place in SCCO₂, and polymerization was proceeding when the pyrrole/PS blend was soaking in the doping solution. Furthermore, various effects of the doping conditions on the conductivity of the PPy/PS composite were investigated. Water and acetonitrile were used as the solvents where the former yielded a higher conductivity of the product. Various doping temperatures were studied and a maximum conductivity was observed at 25 °C. The conductivity also depends on the nature of the oxidant. A bell-shaped profile of the conductivity with respect to the concentration of each oxidant was obtained. The maximum conductivity of the composites with iron compounds as oxidants decreases in the following order of anions: chloride > sulfate > perchloride > nitrate in aqueous solutions. Comparison of the scanning electron microscope results of the composite was presented where chloride and nitrate anions were used as the oxidant. It was found that the composite with higher conductivity has higher bulk density and less porous morphology.     

金纳米棒@碳中空胶囊的制备及催化性能

以聚吡咯为碳壳前驱体制备了金纳米棒镶嵌于碳壳内的中空胶囊.先合成羧基修饰的聚苯乙烯微球和十六烷基三甲基溴化铵稳定的金纳米棒; 再利用二者之间的静电力将金纳米棒组装在聚苯乙烯微球表面; 最后, 通过氧化聚合将聚吡咯壳包覆在聚苯乙烯@金纳米棒复合物的表面.在氮气保护下经高温煅烧, 聚吡咯壳被碳化为碳壳的同时聚苯乙烯微球分解, 从而制得金纳米棒@碳中空胶囊.在煅烧过程中, 由于碳壳的保护, 金纳米棒很好地保持了“棒状”形貌.通过调节吡咯单体的浓度, 可以控制聚吡咯壳和碳壳的厚度.金纳米棒@碳中空胶囊在以NaBH₄为还原剂还原亚甲基蓝的反应中表现出良好的催化活性.     

Preparation of SiO2@polystyrene@polypyrrole sandwich composites and hollow polypyrrole capsules with movable SiO2 spheres inside

In this paper, we describe a flexible method for preparing conducting building blocks: SiO2@polystyrene@polypyrrole sandwich multilayer composites and hollow polypyrrole (PPy) capsules with movable SiO2 spheres inside. First, SiO2@polystyrene (PS) core/shell composites were synthesized, and then SiO2@PS@PPy sandwich multilayer composites were prepared by chemical polymerization of pyrrole monomer on the surface of SiO2@PS composites. Furthermore, hollow polypyrrole capsules with movable SiO2 spheres inside were obtained after removal of the middle PS layer. The diameter of sandwich multilayer composites could easily be controlled by adjusting the dosage of pyrrole monomer. The conductivities of composites increased with the increase of PPy content. After the insulating PS layer was selectively etched, the conductivities of hollow capsules with movable SiO2 spheres inside were much higher than those of the corresponding sandwich multilayer composites.     

单分散核／壳结构导电高分子复合材料的研究（Ⅰ）——单分散核／壳结构聚苯乙烯／聚吡咯的结构表征

导电高分子在光、电、磁等领域表现出的广泛应用前景 ,使它成为材料科学的研究热点 .然而 ,早期发现的导电高分子的不溶不熔性 ,使它在可加工性和机械性能等方面仍面临许多挑战 .核 /壳结构导电高分子与单分散技术的结合 ,无疑为这一领域的研究带来新的生机和活力 .目前仅有的少量文献主要集中报道微米和亚微米级单分散核 /壳导电高分子复合材料的研究 ,大多采用种子乳液聚合法合成 .微米级的种子乳液通常采用以醇为分散介质的分散聚合方法制备 [1～ 3] ,由于种子分散体系要经反复离心分离 ,除去醇类 ,重新分散在水相中再进行核 /壳导电高分…     

Preparation of NiAl double hydroxide@polypyrrole materials for high‐performance supercapacitors

A novel NiAl double hydroxide@polypyrrole (LDH@PPy) core–shell material was designed and fabricated by a facile in situ oxidative polymerization of pyrrole (Py) monomer. The microstructure and morphology of the LDH@PPy composites were determined by X‐ray diffractometer, Fourier transform infrared (FTIR), scanning electron microscopy/transmission electron microscopy, and thermogravimetric and differential thermal, revealing that the polypyrrole (PPy) was successfully coated onto the surface of the NiAl‐LDH (LDH) core and the loading amount of PPy impacted the thickness and the dispersion of the conductive PPy shell. The electrochemical performances of the LDH@PPy composites were also evaluated by cyclic voltammogram, electrochemical impedance spectroscopy, and galvanostatic charge–discharge measurements. The results indicated that the supercapacitor performances were attributed to the synergy of unique core–shell heterostructure and each individual component, where the LDH core provided the high‐energy storage capacity and the PPy shell with networks had high electronic conductivity. These shorted the ion diffusion pathway and made electrolyte ions more easily accessible for faradic reactions to enhance the electrochemical performance of the LDH@PPy composites. It was found that the LDH@PPy composite (LDH@PPy₇) fabricated at 7 mL?L^?1 of Py monomer feed exhibiting the best electrochemical performances with high specific capacitance of 437.5 F?g^?1 at 2 A?g^?1 and excellent capacitance retention of about 91% after 1000 cycles. The work provides a simple approach for designing organic–inorganic core–shell materials with potential application in supercapacitors. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1653–1662     

Graphene oxide embedded P(AAm)/PANI cryogel polymer composites for sensor application against pesticide,nitro compound,and organic dyes

Abstract

Graphene oxide (GO) embedded superporous poly(acrylamide) (P(AAm)) cryogel composites (P(AAm)-GO) were prepared and used as conductive sensor materials. For this goal, the GOs flakes within superporous P(AAm) cryogels were reduced in-situ employing hydriodic acid (HI), hydrazine (N₂H₄), and sodium borohydride (NaBH₄) as reducing agents. Amongst all reduced agents\the highest conductivity was observed for HI reduced P(AAm)-GO (P(AAm)-rGO) with 1.7?×?10^?6±9.7?×?10^?8 S.cm^?1. Then again, this P(AAm)-rGO was used for in-situ synthesis of conductive polymers, poly(aniline) (PANI), and poly(pyrrole) (PPy) by using oxidative polymerization technique. The SEM, FT-IR, TGA and conductivity measurements were done for the characterization of prepared cryogel composites. It was found that the conductivity of P(AAm)-rGO increased 70- and 1400-fold with the presence of PANI and PPy, respectively. Furthermore, potential sensor application of P(AAm)-rGO/conductive polymers were tested against herbicides such as paraquat, glyphosphate (G), and a phenolic compound, 4-nitrophenol (4-NP), and some dyes such as methylene blue (MB), methyl orange (MO). Conductivity of P(AAm)-rGO/PANI decreased 5.3 -fold upon reacting with 10?mL 50?ppm G solution. The sensitivity and effect of G amounts were also tested for P(AAm)-rGO/PANI cryogel composite.     

Novel electromagnetic functionalized γ‐Fe2O3/polypyrrole composite nanostructures with high conductivity

In general, the conductivity of polypyrrole (PPy) is reduced by addition of magnetic nanoparticles as the additives owing to insulating effect of magnetic nanoparticles. In this article, novel electromagnetic functionalized PPy composite nanostructures were prepared by a template‐free method associated with γ‐Fe₂O₃ nano‐needles as the hard templates in the presence of p‐toluene‐sulfonic acid (p‐TSA) and FeCl₃·6H₂O as the dopant and oxidant, respectively. It was found that the molar ratio of γ‐Fe₂O₃ to pyrrole monomer represented by [γ‐Fe₂O₃]/[Py] ratio strongly affected the morphology and the conductivity of the γ‐Fe₂O₃/PPy composite nanostructures. A growth mechanism for the composite nanostructures was proposed based on the variance of the morphology with the [γ‐Fe₂O₃]/[Py] ratio. Compared with previously reported γ‐Fe₂O₃/PPy composites, the as‐prepared novel composite nanostructures showed much higher conductivity (up to ～50 times higher). Moreover, the synthesized γ‐Fe₂O₃/PPy composite nanostructures displayed ferromagnetic behavior with a high coercive force. Explanations for these interesting observations were made in terms of the magnetic interaction between ferromagnetic γ‐Fe₂O₃ nano‐needles and spin‐polaron of PPy nanotubes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4446–4453, 2009     

Synthesis and Characterization of Polyvinylferrocene/Polypyrrole Composites

Conducting polymer composites of polyvinylferrocene and polypyrrole (PVF/PPy) were synthesized chemically by the in situ polymerization of pyrrole in the presence of PVF using FeCl₃ as oxidant. Acetic (CH₃COOH) and boric (H₃BO₃) acids were used as the synthesis medium. Effects of the synthesis medium on the properties of the PVF/PPy composite were investigated. The PVF/PPy composites and homopolymers were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and magnetic susceptibility techniques. Conductivity measurements were performed using the four‐probe technique. We found that the conductivities of PVF/PPy‐H₃BO₃ (1.19 S cm^?1) and PVF/PPy‐CH₃COOH (4.5×10^?1 S cm^?1) increased relative to those of the homopolymers of PPy‐H₃BO₃ (2.1×10^?2 S cm^?1) and PPy‐CH₃COOH (1.2×10^?2 S cm^?1) due to the interaction of PVF with the pyrrole moiety. The stability of all homopolymers and composites were investigated by thermogravimetric analysis and by conductivity measurements during heating‐cooling cycles. There was a small drop in conductivity caused by the annealing of PVF/PPy composites at 70°C. The conductivity of all samples increased with temperature and exhibited stable electrical behavior with increasing temperature. TGA analysis of samples showed that the composites were more stable than the homopolymers or PVF separately. The magnetic susceptibility values of samples were negative, except for PVF/PPy‐H₃BO₃. Morphology changes of the composites investigated by scanning electron microscopy (SEM), attributed to synthesis conditions, have a significant effect on their conductivity.     

Improved lithium exchange at LiFePO4 cathode particles by coating with composite polypyrrole–polyethylene glycol layers

The polypyrrole–LiFePO₄ composites were synthesized by simple chemical oxidative polymerization of pyrrole (Py) monomer directly on the surface of LiFePO₄ particles. Properties of resulting polypyrrole–LiFePO₄ (PPy-LiFePO₄) samples (especially conductivity) are strongly affected by the preparation technique, polymer additives, and conditions during synthesis. For increasing of PPy-LiFePO₄ conductivity, we used polyethylene glycol (PEG) as additive during polymerization. The electrochemical behavior of the samples was examined by cyclic voltammetry and electrochemical impedance spectroscopy. It was found that PPy/PEG composite polymer decreased the particle to particle contact resistance. Impedance measurements showed that the coating of PPy/PEG significantly decreases the charge transfer resistance of LiFePO₄ electrodes.     

In Situ Synthesis of Robust Conductive Cellulose/Polypyrrole Composite Aerogels and Their Potential Application in Nerve Regeneration

Nanostructured conductive polymers can offer analogous environments for extracellular matrix and induce cellular responses by electric stimulation, however, such materials often lack mechanical strength and tend to collapse under small stresses. We prepared electrically conductive nanoporous materials by coating nanoporous cellulose gels (NCG) with polypyrrole (PPy) nanoparticles, which were synthesized in situ from pyrrole monomers supplied as vapor. The resulting NCG/PPy composite hydrogels were converted to aerogels by drying with supercritical CO₂, giving a density of 0.41–0.53 g cm^?3, nitrogen adsorption surface areas of 264–303 m² g^?1, and high mechanical strength. The NCG/PPy composite hydrogels exhibited an electrical conductivity of up to 0.08 S cm^?1. In vitro studies showed that the incorporation of PPy into an NCG enhances the adhesion and proliferation of PC12 cells. Electrical stimulation demonstrated that PC12 cells attached and extended longer neurites when cultured on NCG/PPy composite gels with DBSA dopant. These materials are promising candidates for applications in nerve regeneration, carbon capture, catalyst supports, and many others.     

Dielectric properties of polypyrrole/pillared clay nanocomposites

Dielectric constant ??? and loss factor ??? were measured in intercalated polypyrrole/aluminum pillared montmorillonite (PPy/Al-PMMT) clay nanocomposites in the frequency range 100 Hz to 1 MHz. The PPy/Al-PMMT nanocomposites were prepared by in situ polymerization of pyrrole in aqueous dispersion of varying amounts of (Al-PMMT) clay from 0.2 to 10%, using FeCl₃ · 6H₂O as an oxidant. Formation of the nanocomposite was studied by FTIR and intercalation of PPy in the clay galleries was confirmed by XRD. The nanocomposites exhibited very large values of ??? and ??? at low frequency which decreased with frequency and increased with the clay content in the samples. Electric modulus formalism exhibited a peak in the frequency dependence curves of imaginary part of the electric modulus due to conductivity relaxation process. The peak of conductivity relaxation shifted towards higher frequencies and the magnitude of relaxation decreased with the increase of MMT content in the composites.     

Lab Scale Study on Humidity Sensing and D.C. Conductivity of Polypyrrole/Strontium Arsenate (Sr<Subscript>3</Subscript>(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript>) Ceramic Composites

In-situ polymerization of pyrrole was carried out with strontium arsenate (ceramics) in the existence of oxidizing agent ammonium persulphate to synthesize polypyrrole/strontium arsenate composites by chemical oxidation method. The polypyrrole/strontium arsenate composites were synthesized with various compositions viz., 10 to 50 wt % of strontium arsenate was placed in polypyrrole. The surface morphologies of these composites were analyzed using Scanning Electron Microscopy (SEM) which confirmed the embedment of strontium arsenate particles in PPy chain. The Fourier Transform Infra-Red spectra (FTIR) revealed the shift of lengthens frequencies towards elevated frequency area. The powder X-ray diffraction patterns (XRD) disclosed the crystalline behavior exhibition of the composites. Thermographs of thermal analysis (TG/DTA) exposed the stronger stability of polypyrrole/strontium arsenate composites than PPy. D.C. conductivity reveals that, the strontium arsenate concentration in polypyrrole is accountable for the variant of conductivity of the composites. The results of the study signify the increment of D.C. conductivity for 40 wt % of strontium arsenate in polypyrrole. The temperature reliant conductivity dimension shows the thermally activated exponential behavior of PPy/Sr₃(AsO₄)₂ composites. The reduction in electrical resistance was experienced, when the polymer composites were bare to the wide range of relative humidity (Rh) (from 30 to 95%). This reduce is due to enhance in surface electrical conductivity ensuing from humidity fascination and also due to capillary abridgment of water causing change in conductivity within the sensing materials. The composite shows sensitivity in the range 30 to 95% Rh, we also studied response and recovery time.     

A facile one-pot interfacial synthesis of Pt nanoparticles/polypyrrole composites and their application for non-enzymatic sensing hydrogen peroxide

Pt nanoparticles (PtNPs)/polypyrole (PPy) composites were successfully prepared through a facile one-pot interfacial polymerization of pyrrole by using H₂PtCl₆ as the oxidant for the first time. The as-prepared PPy was granular particles with particle size within a few hundred nanometers, on which PtNPs (1.7–3.5) nm were homogeneously dispersed. The PtNPs/PPy composites displayed excellent electrocatalytic activity toward redox of H₂O₂. The non-enzyme sensor constructed with PtNPs/PPy composites displayed good sensing ability toward H₂O₂ at ?0.1 V with a significantly high sensitivity of 6056 μAmM^?1cm^?2 and a low detection limit of 1.8 μM (S/N = 3).     

Microstructure, distribution and properties of conductive polypyrrole/cellulose fiber composites

Highly intrinsic conductive polypyrrole/cellulose fiber composites (CF) were successfully prepared through in situ chemical oxidation polymerization simply by increasing fiber concentration at the same dosage of pyrrole, oxidant and dopant (based on the weight of dry fiber). FeCl₃ and anthraquinone-2-sulfonic acid sodium salt (AQSNa) were utilized as oxidant and dopant. As fiber concentration increased from 1 % (CF1) to 20 % (CF20), N and S content increased from 0.24 and 0.25 % to 1.24 and 0.89 %, and great increase in the retention of PPy and AQSNa was confirmed by elemental analysis. In addition, on the surface of conductive fiber, PPy of compact fibroid structure was detected instead of interconnected globular structure at higher fiber concentration. Furthermore, scanning transmission electron microscope and X-ray photoelectron spectroscopy (XPS)-depth profile analysis demonstrated denser and more uniformly distributed PPy inside fiber wall for CF20, while PPy tended to deposit on the surface of fiber for CF1. Fourier transform infrared spectroscopy, together with XPS certified that the PPy with longer conjugation length and higher doping level across the conductive fiber was obtained at higher fiber concentration. The doping level for CF10 decreased from 21.55 to 16.39 % with increasing fiber wall thickness, while that of CF20 decreased slightly from 30.73 to 24.10 %. The resulting CF20 showed lowest surface resistivity of 0.433 KΩ/square, as well as improved electro-conductivity stability. The incorporation of more PPy in CF improved the thermal stability.     

Preparation of hollow silica microspheres with controlled shell thickness in supercritical fluids

This article presents a novel route to prepare hollow silica microspheres with well-defined wall thickness by using cross-linked polystyrene (PS) microspheres as templates with the assistance of supercritical carbon dioxide (SC-CO₂). In this approach, the cross-linked PS templates can be firstly prepared via emulsifier-free polymerization method by using ethylene glycol dimethacrylate or divinylbenzene as cross-linkers. Then, the silica shell from the sol–gel process of tetraethyl orthosilicate (TEOS) which was penetrated into the PS template with the assistance of SC-CO₂ was obtained. Finally, the hollow silica spheres were generated after calcinations at 600 °C for 4 h. The shell thickness of the hollow silica spheres could be finely tuned not only by adjusting the TEOS/PS ratio, which is the most frequently used method, but also by changing the pressure and aging time of the SC-CO₂ treatment. Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscope were used to characterize these hollow silica spheres.     

The processing and properties of conductive polypropylene/polypyrrole composites

Polypropylene (PP) particles were chemically coated with polypyrrole (PPy). The content of polypyrrole varied from 0.8 to 7.6 wt.-%. Electrical conductivity of compression moulded samples depends on the concentration of polypyrrole and reached values from 4×10⁻¹⁰ to 5×10⁻³ S/cm, which is about 7 orders of magnitude higher than the conductivity in the blends prepared by mechanical mixing of PP and PPy in the same PPy concentration range. Highly conductive composites were also obtained from a mixture of coated and non-coated PP particles. The PP/PPy composites were characterized by elemental analysis, SEM and mechanical testing. The antistatic properties of PP/PPy composites were demonstrated. The electrical and mechanical properties depend on processing of composites.