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.     

The preparation and properties of sodium and organomodified-montmorillonite/polypyrrole composites: A comparative study

Two montmorillonites, an inorganic sodium montmorillonite (NaMMT) and an organo-modified montmorillonite (OMMT), were used for the preparation of montmorillonite/polypyrrole (MMT/PPy) composites. MMT particles were modified by the in situ polymerization of pyrrole in water, in aqueous solution of dodecylbenzenesulfonic acid (DBSA) used as anionic surfactant, and in water/methanol. Ferric chloride was used as oxidant in each case. Wide angle X-ray scattering (WAXS) measurements proved the intercalation of PPy into the galleries of NaMMT regardless the reaction media. In contrast, for OMMT/PPy composites, the increase of interlayer spacing depends on the preparation conditions, the highest increase in interlayer spacing was achieved in water/DBSA solution. The WAXS patterns of OMMT/PPy composites synthesized in methanol/water showed no change in interlayer spacing and the electrical conductivity of these composites was low, similar to that of NaMMT/PPy composites prepared under the same conditions. Conductivity about 1.1 S cm⁻¹ was reached for OMMT/PPy composites containing 13.3 wt% PPy prepared in the presence of DBSA. The NaMMT/PPy composite containing 15.6 wt% PPy and prepared under the same conditions showed a conductivity of 0.26 S cm⁻¹. X-ray photoelectron spectroscopy (XPS) proved that the surface of NaMMT/PPy composites is rich in MMT, whereas more PPy was found on the surface of OMMT/PPy composites. The conductivity of composites correlated with the N/Si atomic ratio determined from XPS results, which was taken as a semi-quantitative measure of the PPy surface fraction.     

Organic conductor: Influence of preparation temperature

The conducting polypyrrole–polyethylene glycol (PPy–PEG) composite films were produced at various polymerization temperature ranging from 5 °C to 60 °C using 1 × 10^?3 M PEG, 0.20 M pyrrole and 0.10 M p-toluene sulfonate at 1.20 V (vs. SCE). The polymerization temperature of 5 °C appeared as the optimum preparation temperature showing the highest electrical conductivity of 70 S/cm and the thermal diffusivity of 8.76 × 10^?7 m² s^?1. The electrical conductivity and thermal diffusivity exhibited a decreasing trend with the increase in polymerization temperature in the pyrrole solution used to prepare the composite films. The XRD results reveal that low temperature (5 °C) typically results in more crystalline films, which are denser, stronger and have higher conductivity. The optical microscopy of PPy–PEG shows the globular surface morphology. The surface of the of the solution side of PPy–PEG film prepared at low temperatures showed a globular morphology.     

Electrospinning PVDF/PPy/MWCNTs conducting composites

Conducting PVDF/PPy composites (PPy composites) were prepared by using the highly porous electrospun (e-spun) nonwoven web as a host polymer. E-spun nonwoven web was made by electrospinning a solution of PVDF and CuCl₂·2H₂O in solvent of N,N-dimethylacetamide (DMAc). The PPy composites were fabricated by exposing a nonwoven web containing oxidant to pyrrole vapors. Field-emission scanning electron microscopy (FE-SEM) analysis was conducted to show the microstructure of the nonwoven webs and the uniform coating of PPy on the e-spun fiber surfaces of the PPy composite. The information of PPy on the e-spun fibers surface was confirmed by attenuated Fourier-transform infrared spectrometer (ATR FT-IR) and X-ray photoelectron spectroscope (XPS). The thermal property of PPy composites was also investigated by differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA). The electrical conductivity of the PPy composites was affected by the fabrication method and oxidant content in the nonwoven web. The electrical conductivity and mechanical strength of the PPy composites were improved when surface-modified multi-walled carbon nanotubes (MWCNTs) were added to the e-spun fibers. Energy-filtered transmission electron microscopy (EF-TEM) results confirmed that the MWCNTs were well arranged and embedded in the e-spun fibers. The observed conductivity of the conducting PPy-MWCNTs composite was 10^?1 S/cm.     

Conducting behaviors of PPy/ITO composites synthesized by polymerization

Conducting composites core layers of indium tin oxide (ITO) particles embedded in polypyrrole (PPy) were prepared by polymerization. The morphology, molecular structure and electrical property of the composites were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscope, thermogravimetric analysis and conductivity measurement methods. The results indicated the ITO combined with PPy by chemical bond energy not the physical combine. Electrical conductivity measurements on the samples pressed into pellets showed that the maximum conductivity attained 13.97 ± 0.05 S/cm for PPy/ITO composites, at ITO particle doping concentration of 50 wt%. The highest conductivity of PPy/ITO crossing-rod composites was 11.00 ± 0.05 S/cm, of which the content of ITO crossing-rod was 15 wt%. The PPy/ITO composites showed a higher conductivity by comparing with that of neat PPy.     

Preparation and properties of conducting polypyrrole-sulfonated polycarbonate composites

The electrically conducting composites are prepared by chemical oxidative polymerization using polypyrrole (PPy) and polycarbonate (PC) or sulfonated polycarbonate (SPC) in chloroform. The pyrrole was protonated and polymerized using iron(III) chloride (FeCl₃). The sulfonic group was introduced into the structure of PC in order to enhance the coulombic interaction between each phase of composites. The electrical conductivity and morphology were observed as a function of the amount of PPy. The electrical conductivity was increased up to 0.82 S/cm with the amount of PPy. The PPy/SPC composites were stable in atmosphere.     

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.     

Electrodeposited conducting polymer–magnetic metal composite films

Electrically conducting polypyrrole (PPy)–iron group (Ni, Co, Fe and their alloys) composite films have been electrodeposited at cathodic process to give “tailored” soft and hard magnetism. The composites of the PPy doped with dodecylsulfate (DS) (PPy–DS) with NiFe alloy showed soft magnetism with coercivity H_C,∥ <9 Oe, while the PPy–DS with CoMnP alloy showed hard magnetism with H_{C, ∥}>1085 Oe. These results indicate that composites of conducting polymer–magnetic metals can be easily fabricated by electrodeposition.     

Actuation behaviour of layered composites of polyaniline,carbon nanotubes and polypyrrole

Layered composites of polyaniline (PAn), single-walled carbon nanotubes (CNTs) and polypyrrole (PPy) were produced by coating PAn or PAn/CNT on a PPy hollow fibre containing a platinum (Pt) helix. The actuation behaviour of PAn/PPy and PAn/CNT/PPy composites was compared with that of neat PPy. The Pt helix reduces the IR drop along the fibre, thus enhancing the actuation strain. Components of the composite with low actuation strain such as PAn and/or CNT restrict the actuation displacement of the PPy substrate causing a reduced strain in the composite. In particular, a minimal quantity of CNT (1.3 wt.%) in the composite leads to a discernible decrease in actuation strain but also increases the Young's modulus and tensile strength of the composite. Sodium nitrate (1 M) aqueous solution used as an electrolyte gives good actuation stability where the actuation strain is almost independent of applied stress (5–12 MPa). This can be explained by the unchanged Young's modulus at the reduced (contracted) and oxidized (expanded) states during the actuation process. The polyaniline/polypyrrole composite produced the highest work-per-cycle reported to date under isotonic conditions.     

Polypyrrole nanowire modified graphite (PPy/G) electrode used in capacitive deionization

With high specific capacitance and good conductivity, polypyrrole nanowire modified graphite (PPy/G) electrode has great promising applications in capacitive deionization (CDI). Preparation parameters of modified electrode such as concentration of supporting electrolyte solution (LiClO₄), concentration of monomer (pyrrole, Py), pH of polymerization medium, polymerization potential and time have significant effects on the electrode adsorption capacity of NaCl. The experimental results indicate that the optimal preparation condition of the PPy/G electrode used for CDI is 0.10 M LiClO₄, 0.19 M Py and pH 5.91 which was controlled by phosphates buffer solution (PBS, 0.10 M), polymerized at 0.85 V vs saturated calomel electrode (SCE) with polymerization time of 150 s. The obtained electrode has an area specific capacitance of 0.188 F/cm² determined by cyclic voltammetry (CV) method in 1.0 M HClO₄ at a scanning rate of 0.05 V/s. In addition, the desalination experiments of the electrode were carried out in 500 ppm NaCl solution at a working voltage of 1.4 V. The experimental results indicate that the NaCl can be removed from the feed solution by electroadsorbing of the electrode with good desalination stability and the electrode can be regenerated efficiently by its electrodesorbing.     

Polypyrrole-polyethylene glycol conducting polymer composite films: Preparation and characterization

The preparation and characterization of polypyrrole-polyethylene glycol (PPy-PEG) composite films are reported in this present paper. The polypyrrole-polyethylene glycol composites were synthesized by electrochemical method, using p-toluene sulfonate as a dopant in aqueous medium. The composite films were synthesized with various concentration of PEG and were characterized by optical microscopy, x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, photoacoustic spectroscopy and electrical conductivity measurement. Both the electrical conductivity and thermal diffusivity exhibited the highest values with the process condition of 0.2 M pyrrole, 0.1 M p-toluene sulfonate and 1×10⁻³ M PEG at 1.2 V (versus SCE). The optical microscopy of PPy-PEG shows the globular surface morphology. The XRD results demonstrated that PPy-PEG composite films are amorphous. The FTIR result reveals the successful incorporation of PEG into the PPy structure forming PPy-PEG composite films.     

The role of anthraquinone sulfonate dopants in promoting performance of polypyrrole composites as pseudo-capacitive electrode materials

We report the role of anthraquinone sulfonate dopants in promoting performance of electro-synthesized polypyrrole (PPy) composites for use in electrochemical supercapacitors. The incorporation of anthraquinone sulfonate species into the polymer matrix can significantly improve the surface area of PPy composites that are composed of submicron-/nano-sized particles, as evidenced from scanning electron microscopy (SEM) results. Cyclic voltammetry and galvanostatic charge–discharge measurements in 1 M KCl solution reveal that these dopants result in an improved specific capacitance, a wide working potential range and enhanced long-cycle stability as compared to ClO₄^? dopant. Among the samples investigated, the resulting PPy/AQS (9,10-anthraquinone-2-sulfonic acid sodium salt) composite exhibits the highest specific capacitance of 608 F g^?1 at a scan rate of 5 mV s^?1 within a potential range between ?0.9 and 0.5 V (vs. saturated calomel electrode, SCE).     

Multi-functional polypyrrole nanofibers via a functional dopant-introduced process

This paper reports a functional dopant-introduced route to synthesize polypyrrole (PPy) nanofibers (60–100 nm in average diameter) in the presence of p-hydroxyl-azobenzene sulfonic acid (p-OH-ABSA) as a functional dopant. The nanofibers show a high conductivity (120–130 S/cm) and photoisomerization, which resulted from proton doping and photoisomerization of azobenzene moiety, respectively. Static and dynamic light scattering as well as freeze-fracture replication transmission electron microscope measurements (FFRTEM) showed that the self-assembled cylindrical micelles act as “soft-templates” during the formation of the nanofibers. Influence of polymerization conditions, such as the type of oxidant, the rate of oxidant addition, the concentration of reactants and polymerization time, on the fibrous morphology of PPy-(p-OH-ABSA) has been investigated. The characterizations of molecular structure, photoisomerization and electrical properties have been carried out. The method described in this study provides a simple and inexpensive route to prepare multi-functional nano-structured conducting polymers.     

Polyaniline nanofibers synthesized in compressed CO2

Polyaniline (PANI) nanofibers were synthesized in compressed liquid carbon dioxide without any template or surfactant. The polymerization of aniline took place at the interface between CO₂ and aqueous solution in a high-pressure stirred reactor. The prepared PANI nanofibers were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), electrical conductivity (EC), Fourier-transform infrared (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analyses. The yield of polymerization was high enough to reach 63.04% while maintaining small diameters of the PANI nanofibers. This result is very important for the preparation of the PANI nanofibers because no other previous investigations have achieved both high yield and small diameter of fibers at the same time. Through SEM and TEM analyses, we observed that the PANI nanofibers had diameter range of 30–70 nm and a length range of 0.3–1 μm, which caused them to disperse well in various solvents such as water, ethanol, 2-propanol, m-cresol and toluene. The electrical conductivity of the PANI nanofibers was 4.34 S/cm at 20 °C. The XRD diffraction pattern showed that the PANI nanofibers had crystalline one-dimensional structures, which gave high thermal stabilities as confirmed by TGA.     

Preparation and characterization of a polypyrrole hybrid film with [Ni(dmit)2]2−, bis(1,3-dithiole-2-thione-4,5-dithiolate)nickellate(II)

The synthesis of a hybrid material obtained by electropolymerization of a solution of pyrrole and [NEt₄]₂[Ni(dmit)₂] (dmit = 1,3-dithiole-2-thione-4,5-dithiolato) in acetonitrile solution is reported. The material was characterized by cyclic voltammetry, UV–vis and infrared spectroscopies, scanning electron microscopy (SEM), atomic force microscopy (AFM) and thermal gravimetric analysis (TGA). The FTIR spectroscopy showed that the [Ni(dmit)₂]²⁻ anion has been inserted in the polypyrrole framework and was not destroyed or modified during the polymerization process. The voltammetric analysis indicated that the material has electroactivity and undergoes redox processes associated with the conducting polymer and the counteranion. The cyclic voltammetry results also suggest that the counteranion is not trapped in the PPy matrix undergoing anion exchange during the redox cycle of PPy. The PPy/[Ni(dmit)₂]²⁻ exhibits good thermal stability and a intrinsic conductivity value in the range of semiconductors (10⁻³ S cm⁻¹).     

聚乳酸-聚吡咯/银多层复合抗菌薄膜的制备与性能表征

目的提高聚乳酸(PLA)薄膜的抗菌性能。方法受到导电高分子材料可以通过静电作用方式起到抗菌作用的启发,利用Fe~(3+)引发吡咯(Py)在PLA薄膜表面发生化学氧化反应,聚合形成抗菌涂层(PPy),成功制备出PLA-PPy多层复合抗菌薄膜。采用等物质的量Ag~+替代Fe~(3+),引发Py在PLA薄膜表面聚合形成双重抗菌涂层(PPy/Ag),成功制备出PLA-PPy/Ag多层复合抗菌薄膜,并探讨了不同氧化剂和Py浓度对多层复合薄膜结构和性能的影响。结果当PLA薄膜表面积为72 cm~2,水溶液体积为40 mL,Fe Cl_3·6H_2O的浓度为0.047 mol/L,Py的浓度为0.223 mol/L时,PLA-PPy多层复合薄膜的表面PPy层结构致密,拉伸强度(40.1 MPa)和断裂伸长率(24.9%)分别降低了7.6%和12.6%,热稳定性得到较为明显的提高。此外,PLA-PPy/Ag与PLA-PPy多层复合薄膜表现出相似的力学性能和热稳定性。更为重要的是,相比于PLA-PPy多层复合薄膜,PLA-PPy/Ag多层复合薄膜表现出更为优异的抗菌特性,大肠杆菌的菌落总数降低至2.9×10~6 CFU/cm~2,相比于纯PLA薄膜(4.8×10~(10) CFU/cm~2),降低了超过4个数量级。结论相比于完全采用成本较高的纳米银离子负载抗菌方式来说,较低成本的双重抗菌涂层(PPy/Ag)将会在PLA活性包装领域具有一定的研究意义。     

Fabrication of Pt nanoparticles decorated PPy–MWNTs composites and their electrocatalytic activity for methanol oxidation

Here we report the synthesis and characterization of a catalyst material constituted of Pt, polypyrrole (PPy) and multi-walled carbon nanotubes (MWNTs). The catalyst supports (PPy–MWNTs nanocomposites) were synthesized via in situ chemical polymerization in advance, in which MWNTs were regarded as the matrix material. The supports were characterized by SEM & TEM, elemental analysis, XRD, FTIR and conductivity measurements. Then the catalysts were synthesized by a chemical reduction using sodium borohydride (NaBH₄) as reducing agent and acetic acid buffer (pH = 4) containing trace K₂C₂O₄ as reaction media. FTIR spectra showed that there existed relations between PPy and MWNTs during in situ polymerization. SEM and TEM micrographs of the catalyst samples exhibited that the existence of PPy layer which was evenly wrapped on the surface of MWNTs resulted in significant improvement in helping Pt particles well dispersed. XRD results showed that higher Pt(1 1 1) content in the catalyst deposited on PPy–MWNTs supports than that on MWNTs. The cyclic voltammetry (CV) tests of methanol electrocatalytic oxidation demonstrated that the electrode modified by Pt/PPy–MWNTs ternary composite catalyst showed higher catalytic stability than Pt/MWNTs binary catalyst, due to the synergic interaction between Pt and the carrier.     

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.     

High charge/discharge rate polypyrrole films prepared by pulse current polymerization

Polypyrrole (PPy) films doped by p-toluenesulfonic (PTS) ion were prepared by pulse current polymerization (PCP PPy) and direct current polymerization (DCP PPy) in aqueous solution. During polymerization of DCP PPy films, the sustained high anodic potentials can result in overoxidation and –CH₂– formation at pyrrole rings, which was confirmed by the FTIR spectroscopy. PCP PPy films exhibited more homogeneous and smoother appearance than DCP PPy films. The apparent diffusion coefficient of PCP PPy films was one order of magnitude bigger than that of DCP PPy films, which was closely correlated with the more ordered structure of PCP PPy films confirmed by XRD. When the scanning rate reached up to 500 mV s^?1, the CV curves of PCP PPy films showed rectangular shape within voltage range of ?0.8 V to +0.8 V. High charge/discharge rate of PCP PPy films can be attributed to well wettability, very small charge transfer resistance, high electronic conductivity and ions apparent diffusion coefficient. After 50,000 charge/discharge cycles, the specific capacitance of PCP PPy films only decreased by 14% at a charge/discharge current of 20 A g^?1 within voltage range of 0–0.4 V.     

Chemical oxidative polymerization of pyrrole in the presence of m-hydroxybenzoic acid- and m-hydroxycinnamic acid-related compounds

Chemical oxidative polymerization of pyrrole was performed in the presence of two families of aromatic compounds with electron-withdrawing substituents. The first one includes 3-hydroxybenzoic acid (HBA) and two HBA-related compounds, such as 6-hydroxypicolinic acid (HPA) and citrazinic acid (CA). The second one includes trans-3-hydroxycinnamic acid (HCA) and two HCA-related compounds, such as trans-4-hydroxy-3-methoxycinnamic acid (HMA) and urocanic acid (UA). It was found that HBA, HPA and HCA enhance both the conductivity and stability of the resulting PPy. UA improves only the PPy stability whereas CA and HMA lead to low conducting PPy. Maximum PPy conductivity values of 81, 74 and 123 S/cm were obtained by using [HBA]=0.25 M, [HPA]=0.025 M and [HCA]=0.025 M, respectively. Elemental analysis data and FTIR results showed no incorporation of the additives to the obtained PPy, except for HMA. The formation of additive-iron(III) charge–transfer complexes was identified by means of UV spectroscopy of the starting solutions containing the organic additive and FeCl₃·6H₂O. The redox potential of these solutions was affected by the presence of the HBA- and HCA-related compounds.