Synthesis and electrochemical applications of the composites of conducting polymers and chemically converted graphene

Conducting polymers (CPs) have been widely applied for fabricating various electrochemical devices such as sensors, actuators, solar cells, etc. To extend the functions or improving the performances of the devices, CPs frequently have to be blended with other functional materials to form composites. Graphene, a one-atom layer of graphite with unique two-dimensional structure and excellent mechanical and electrical properties, has become an increasing star in material science. Chemically converted graphene (CCG) prepared by reducing graphene oxide has satisfied processing property and complementary properties with CPs. Therefore, CCG is an important functional component for preparing high-performance CP-based composites. In this critical review, we mainly summarize the recent advancements in our group on the synthesis of CP/CCG composites and their electrochemical applications including supercapacitors, solar cells and electroanalysis.     

Synthesis, characterization and electrochromic properties of a near infrared active conducting polymer of 1,4-di(selenophen-2-yl)-benzene

A novel selenophene-based monomer, 1,4-di(selenophen-2-yl)-benzene (DSB), was synthesized via Stille coupling reaction of 1,4-dibromobenzene and tributyl(2-selenophenyl)stannane. Conducting polymer (PDSB) was prepared electrochemically in the presence of tetrabutylammonium hexafluorophosphate (TBAPF₆) as the supporting electrolyte in dichloromethane (DCM). The resulting conducting polymer was characterized by Cyclic Voltammetry, Fourier Transform Infrared and Ultraviolet-visible spectroscopy. Spectroelectrochemistry analysis and kinetic studies of PDSB revealed a π-π^∗ transition at 340 nm with a striking and rapid (0.6 s) transmittance change (35%), at near infrared region (1250 nm), indicating that PDSB is a very suitable near infrared electrochromic material.     

Synthesis, characterization and electrochromic properties of a conducting copolymer of pyrrole functionalized polystyrene with pyrrole

A well-defined polystyrene (PSt) based polymer containing at one end-chain 3,5-dibromobenzene moiety, prepared by atom transfer radical polymerization (ATRP), was modified in two reaction steps. First one constitutes a Suzuki coupling reaction between aromatic dibromine functional polymer and 3-aminophenylboronic acid, when a diamino-containing intermediate was obtained. The second step is a condensation reaction between the diamino functional polystyrene and 2-pyrrole aldehyde. Thus, a polymer containing a conjugated sequence having pyrollyl groups at the extremities was synthesized. The presence of oxidable pyrrole groups in the structure of the polymer permitted further electropolymerization. The structures of intermediate polymers were analyzed by spectral methods (¹H NMR, FTIR). Electrochemical copolymerization of pyrrole functionalized polymer (PStPy) with pyrrole was carried out in acetonitrile (ACN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couple. Characterization of the resulting copolymer were performed via Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), spectroelectrochemical analysis, and kinetic study. Spectroelectrochemical analysis show that the copolymer of PStPy with Py has an electronic band gap (due to π-π* transition) of 2.4 eV at 393 nm, with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Via kinetic studies, the optical contrast %ΔT was found to be 20% for P(PStPy-co-Py). Results showed that the time required to reach 95% of the ultimate T was 1.7 s for the P(PStPy-co-Py).     

Facile synthesis of metal nanoparticles using conducting polymer colloids

We report a simple method to synthesize Ag, Au, and Pt nanoparticles with a reasonable size dispersity using water-dispersible conducting polymer colloids composed of polyaniline (PANI) and conventional polyelectrolyte. This facile synthesis results in single crystalline metal nanoparticles that are stable in an aqueous solution for at least several weeks. The process involves incrementally adding a metal ion solution to aqueous conducting polymer colloids and does not require reducing agents such as NaBH₄. In addition, the complete synthetic and purification procedure is carried out in an aqueous solution; therefore, it is environmentally benign and potentially suitable for large-scale production. We have also demonstrated synthesis of larger nanoparticles and nanosheets by varying the experimental parameters. With the tunable oxidation states of conducting polymers, we expect this synthetic platform can synthesize a wide range of nanostructured metals with specific size, shape and properties. Finally, the nanoparticles embedded in the conducting polymer matrix, the metal-polyaniline nanocomposite itself may be interesting since it represents a type of materials where metallic nanoislands are embedded in a semiconducting matrix.     

Sialon陶瓷材料的结构、性质及应用

系统地评述了不同种类单相Sialon陶瓷的结构特征和物理、化学性质,并介绍了Sialon在冶金工业等方面的应用.单相Sialon陶瓷中,β'-Sialon强度和韧性最高,α'-Sialon硬度和耐磨性最好,O'-Sialon抗氧化性最佳.     

Synthesis and characterization of chemically and electrochemically prepared conducting polymer/iron oxalate composites

Poly(3-octyl-thiophene) (POT) and polypyrrole (PPy) iron oxalate composites were synthesized through a post-polymerization oxidative treatment. The composite of the latter has been prepared also by electrochemical polymerization. The samples have been characterized by X-ray diffraction (XRD), impedance spectroscopy, scanning electron microscope (SEM) combined with energy dispersive X-ray (EDX) spectroscopy, Mössbauer spectroscopy, cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). In case of PPy, two peaks in the XRD spectra show the presence of iron containing composite, while with POT only the layered structure originating from the octyl side-chain interactions was modified by the composite formation. The assumption of the weakening of short- and long-range interactions was proven by the decrease in conductivity of the composite. The successful electrochemical synthesis resulted a composite of ∼5% iron content, determined by EDX. Mössbauer spectroscopy measurements evidenced a composite containing mixed valence iron oxalate doping ions, which supports the indirect EQCM data.     

Synthesis of novel sunflower-like silica/polypyrrole nanocomposites via self-assembly polymerization

Novel sunflower-like organic-inorganic composites consisting of spherical silica and smaller conductive polypyrrole particles were successfully prepared through an in situ self-assembly polymerization process by choosing chitosan as a modifying agent of silica surface. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that on the surface of individual silica particle polypyrrole nanoparticles were anchored perfectly. The sunflower-like silica-polypyrrole composites exhibited conductivity of 8 S cm⁻¹ and colloid stability because of the special surface morphology. Adsorbed chitosan chain may play a dual-role of both providing the active sites for formation of the polypyrrole particles on silica and acting as a stabilizer of the silica-polypyrrole particles. Hydrogen-bonding interaction between the acetylamino group of chitosan and hydrogen atom on nitrogen of polypyrrole is a determining parameter in the former case.     

Redox-active conducting polymers incorporating ferrocenes. Preparation, characterization and bio-sensing properties of ferrocenylpropyl and -butyl polypyrroles

The multi-step synthesis of the novel ferrocene-substituted pyrrole monomers, N-(3-ferrocenylpropyl)pyrrole (1), and 3-(4-ferrocenylbutyl)pyrrole (2), have been studied and optimized. A single crystal X-ray structure analysis has been performed on the synthetic intermediate 3-(4-ferrocenylbutyl)-N-(triisopropylsilyl)pyrrole. Monomers 1 and 2 can be electropolymerized to form the homopolymer, poly-2, and the copolymers, pyrrole-co-1 and pyrrole-co-2. The polymers have been characterized using cyclic voltammetry, UV-visible spectroscopy, scanning electron microscopy (SEM) and four-point probe conductivity measurements. The use of pyrrole-co-1 coatings for quantitative sensing and determination of the redox-active enzyme cytochrome C in solution has been demonstrated.     

Preparation of the thermally stable conducting polymer PEDOT - Sulfonated poly(imide)

We describe the template polymerization of EDOT with sulfonated poly(amic acid) (SPAA), resulting in a stable conducting polymer aqueous dispersion, PEDOT-SPAA, with particle size ca. 63 nm. In films of PEDOT-SPAA, the sulfonated poly(amic acid) template undergoes imidization within 10 min at temperatures greater than 150 °C, resulting in PEDOT-sulfonated poly(imide) (PEDOT-SPI) with 10-fold conductivity enhancement. This material is highly thermally stable as compared to PEDOT-PSS. Thermal stability is necessary for many processing applications of conducting polymers, including annealing for OPVs and melt-processing of polycarbonate for device encasement. Isothermal TGA experiments were run at 300 °C for PEDOT-PSS and PEDOT-SPAA and we found that PEDOT-SPAA had a smaller slope for degradation. Annealing of films at 300 °C for 10 min caused the conductivity of PEDOT-PSS films to be unmeasurable (<1 × 10⁻⁵ S/cm), while those of PEDOT-SPAA increased 6-fold. Secondary doping of the PEDOT-SPAA system with additives commonly used for PEDOT-PSS was also investigated.     

A comparative study on electrochemical co-deposition and capacitance of composite films of conducting polymers and carbon nanotubes

Composite films of carbon nanotubes (CNTs) with polyaniline (PANI), polypyrrole (PPY) or poly[3,4-ethylenedioxythiophene] (PEDOT) were prepared via electrochemical co-deposition from solutions containing acid treated CNTs and the corresponding monomer. In the cases of PPY and PEDOT, CNTs served as the charge carriers during electro-deposition, and also acted as both the backbone of a three-dimensional micro- and nano-porous structure and the effective charge-balancing dopant within the polymer. All the composites showed improved mechanical integrity, higher electronic and ionic conductivity (even when the polymer was reduced), and exhibited larger electrode specific capacitance than the polymer alone. Under similar conditions, the capacitance was enhanced significantly in as-prepared PPY-CNT and PEDOT-CNT films. However, the fresh PANI-CNT film was electrochemically similar to PANI, but PPY-CNT and PEDOT-CNT differed noticeably from the respective polymers alone. In continuous potential cycling tests, unlike the pure polymer and other composite films, PANI-CNT performed much better in retaining the capacitance of the as-prepared film, and the possible cause is analysed.     

Polyindene/organo‐montmorillonite conducting nanocomposites. I. Synthesis,characterization, and electrokinetic properties

In this study, Na‐montmorillonite was organically modified with cetyltrimethylammoniumbromide (CTAB) and intercalated with in‐situ polymerized indene. Polyindene(PIn)/Organo‐MMT nanocomposites were obtained with three different compositions and coded as: K1: [PIn(94.5%)/O‐MMT(5.5%)], K2: [PIn(92.8%)/O‐MMT(7.2%)], and K3: [PIn(87.9%)/O‐MMT(12.1%)]. These nanocomposites were subjected to full characterization with various techniques. Electrokinetic studies were conducted to reveal the zeta (ζ)‐potential characteristics of the nanocomposites. ζ‐potentials of the materials were observed to decrease with increasing O‐MMT content. The cationic (CTAB) and anionic (sodium dodecylsulfate) surfactants were shifted the ζ‐potentials of the colloidal dispersions to more positive and more negative regions, respectively whereas nonionic surfactant (Triton X‐100) caused almost no change. The pH and temperature were observed to shift the ζ‐potential values of the nanocomposites to more negative and slightly more positive regions, respectively. With the addition of mono (NaCl), di (BaCl₂) and three (AlCl₃) valent salts, the ζ‐potential of the nanocomposites were shifted to more negative, more positive, and much more positive regions, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of conducting polyaniline‐activated carbon nanocomposites

Conducting polyaniline (PAni)/activated carbon (AC) nanocomposites were synthesized by the in situ chemical polymerization method. The resultant shell–core PAni–AC nanocomposites were characterized by elemental analysis, Fourier transform infrared, scanning electron microscopy, thermal gravimetric analysis, X‐ray diffraction, and transmission electron microscopy. We did not observe any significant chemical interaction between the PAni and AC, only core–shell coupling between the AC and the tightly coated polymer chain was revealed. Measurement of the physical properties showed that the incorporation of conducting PAni on to AC particles during chemical synthesis increased electrical conductivity and thermal stability by several orders of magnitude to that of the pristine PAni powders. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1973–1977, 2007     

氧氮化铝陶瓷的合成与应用

介绍了氧氨化铝的基本性能、合成研究的最新进展、烧结及其抗氧化性、热稳定性和应用。     

Novel electrically conducting polyurethanes with oligoanilines: Synthesis,conductivity, and electrochemical properties

New class of conducting polyurethanes (CPUs) containing oligoanilines, namely tetraaniline (TAni) or trianiline (TriAni), in the backbone have been synthesized and characterized by formal spectral techniques. The unique properties of these CPUs, viz., electronic conductivity and electrochemical activity arising from the presence of oligoaniline units have been evaluated. The basic polyurethane backbone is derived from toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, and polypropylene glycols of molecular weight 425 and 2000. In the first category of polyurethanes, the prepolymers obtained from the above reactants were chain terminated by TAni in emeraldine base oxidation state. The conductivity of these CPUs films ranged from 1.2 × 10^?5 to 1.77 × 10^?3 S cm^?1. These polymers showed lower conductivity due to the presence of nonconjugated polyurethane segments. These CPUs exhibited slightly different electrochemical activity than that of TAni. The second category of CPUs is obtained from prepolymers by chain extension with TriAni. The conductivity of these polymers is similar to the TAni analogues but are electrochemically inactive. The anticorrosion properties of two of these polymers have also been evaluated in this study. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40794.     

Preparation and anticorrosive properties of PANI/Na-MMT and PANI/O-MMT nanocomposites

Nanocomposites of polyaniline (PANI) with organophilic montmorillonite (O-MMT) and hydrophilic montmorillonite (Na-MMT) were prepared. The nanocomposites were characterized using FT-IR, D.C. electrical conductivity measurement and cyclic voltammetry techniques. It was found that PANI/Na-MMT nanocomposite has lower (5.8%) and PANI/O-MMT nanocomposite has higher (29.4%) conductivity compared to pure polyaniline. Cyclic voltammetry experiments showed that both nanocomposites are electroactive. The anticorrosive properties of a 100 μm thickness coating of nanocomposites on iron coupons were evaluated and compared with pure polyaniline coating. According to the results PANI/MMT nanocomposites have enhanced corrosion protection effect in comparison to pure polyaniline coating. Results showed also that the PANI/Na-MMT and PANI/O-MMT nanocomposites have considerably different corrosion protection efficiencies in various corrosive environments.     

A soluble self-doped conducting polyaniline graft copolymer as a hole injection layer in polymer light-emitting diodes

We demonstrate that a novel soluble self-doped conducting polyaniline graft copolymer can be used for a hole injection layer (HIL) in polymer light-emitting diodes (PLEDs). The work function of the material (5.18 eV) was similar to that (5.20 eV) of a conventional conducting polymer dispersion, poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS). When we fabricated PLEDs by using this material, the current-voltage-luminescence characteristics were very similar to those of the device using the PEDOT/PSS. When the material was blended with PSS, the luminous efficiency was further improved up to 11.9 cd/A. Since this kind of soluble type HIL has advantages over the conventional PEDOT/PSS dispersion in terms of the solution processibility and film quality, this soluble graft-type conducting polymer can be one of the promising candidates for a HIL in PLEDs.     

Electrochemical synthesis and In situ spectroelectrochemistry of conducting NMPy‐TiO2 and ZnO polymer nanocomposites for Li secondary battery applications

Poly(N‐methylpyrrole) (PNMPy), poly(N‐methylpyrrole‐TiO₂) (PNMPy‐TiO₂), and poly (N‐methylpyrrole‐ZnO) (PNMPy‐ZnO) nanocomposites were synthesized by in situ electropolymerization for cathode active material of lithium secondary batteries. The charge–discharging behavior of a Li/LiClO₄/PNMPy battery was studied and compared with Li/LiClO₄/PNMPy‐nanocomposite batteries. The nanocomposites and PNMPy films were characterized by cyclic voltammetry, in situ resistivity measurements, in situ UV–visible, and Fourier transform infra‐red (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The differences between redox couples (ΔE) were obtained for polymer nanocomposites and PNMPy films. During redox scan, a negative shift of potential was observed for polymer nanocomposite films. Significant differences from in situ resistivity of nanocomposites and PNMPy films were obtained. The in situ UV–visible spectra for PNMPy and polymer nanocomposite films show the intermediate spectroscopic behavior between polymer nanocomposites and PNMPy films. The FTIR peaks of polymer nanocomposite films were found to shift to higher wavelengths in PNMPy films. The SEM and TEM micrographs of nanocomposite films show the presence of nanoparticle in PNMPy backbone clearly. The result suggests that the inorganic semiconductor particles were incorporated in organic conducting PNMPy, which consequently modifies the properties and morphology of the film significantly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41526.     

New polymer syntheses. IX. Synthesis and properties of new conducting polyazomethine polymers containing main chain cycloalkanone and pyridine moieties

Novel polyazomethines containing cycloalkanones or pyridine moieties were synthesized by the polycondensation of 2,5‐bis(m‐aminobenzylidene)cyclopentanone (BMAP, IV), 2,6‐bis(m‐aminobenzylidene)cyclohexanone (BMAH, V), 2,6‐bis(p‐aminobenzylidene)cyclohexanone (BPAH, VI), and 2,6‐bis(m‐aminostyryl)pyridine (BMAS, VIII) diamines with terephthalaldehyde in EtOH at 25°C. These polymers were yellow to orange in color, had reduced viscosities up to 1.42 dL/g, and had electric conductivities as high as 10⁻¹¹–10⁻¹² S cm⁻¹. All the polyazomethines were insoluble in common organic solvents but dissolved completely in concentrated sulfuric acid. However, they were readily hydrolyzed in concentrated H₂SO₄. X‐ray diffraction diagrams showed that the crystallinities of the polyazomethines were low. These azomethine polymers showed high thermal and thermooxidative stability and exhibited no appreciable decomposition up to 400°C in air. The electronic spectra of the polymers indicated a large bathochromic shift of the π–π* absorption band (∼360 nm) that was due to the presence of CN bonds in the polymer main chain. Doping with iodine dramatically raised the conductivity and produced dark brown to black colored semiconductive polymers with a maximum conductivity on the order of 10⁻⁷ S cm⁻¹. Furthermore, the morphology of selected examples of the four polyazomethines was examined by scanning electron microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1218–1229, 2000     

空心玻璃微珠/环氧树脂复合材料的性能与应用

本文详细介绍了空心玻璃微珠的添加对环氧树脂力学性能的影响,同时综述了这种复合材料的应用情况,并对其应用前景进行了展望。     

Synthesis and potential applications of silicon carbide nanomaterials / nanocomposites

The rapid development of nanotechnologies has accelerated the research in silicon carbide (SiC) nanomaterial synthesis and application. SiC nanomaterials have unique chemical and physical properties, such as distinctive electronic and optical properties, good chemical resistance, high thermal stability, and low dimensionality. These properties lead to a wide range of applications. The progress in SiC nanomaterials in recent years is significant, but a review of the progress is lacking. This article is designed to fill the gap. The review first summarizes various methods for preparing different SiC nanomaterials/nanocomposites, including the carbothermal method, chemical vapor deposition method, and other synthesis techniques using unconventional energy sources such as microwave, plasma, solar energy, and neutron irradiation. Discussion is then made on the significant applications of the SiC nanomaterials/nanocomposites, especially in sensors, catalyst supports, energy storage materials, structural reinforcement, and semiconductor materials. Finally, the conclusion of this review is made with the possible future development trends.