Polypyrrole/carbon nanotube composites: Molecular modeling and experimental investigation as anti-corrosive coating

In this work we present a computational method based on molecular mechanics (MM) and dynamics (MD), to predict mechanical properties of polypyrrole (PPy)/polyaminobenzene sulfonic acid-functionalized single-walled carbon nanotubes (CNT-PABS) and PPy/carboxylic acid-functionalized single-walled carbon nanotubes (CNT-CA) composites. Furthermore, experiments were carried out to assess the anticorrosive features of the PPy film and CNT-PABS and CNT-CA PPy reinforced composite coatings. Computational bulk models of PPy/CNT-PABS and PPy/CNT-CA were implemented at atomistic scale and composite coatings were grown in situ onto carbon steel (OL 48-50) electrodes. PPy, PPy/CNT-PABS and PPy/CNT-CA computational models and films were investigated concerning mechanical properties by using computational tools. The obtained films were assessed experimentally as anticorrosive materials using potentiodynamic measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results clearly confirmed that the CNT-PABS and CNT-CA are properly dispersed in the composite coatings and have beneficial effect on mechanical integrity. Moreover, the anticorrosion protecting ability of the composite coatings is significantly higher than the one characteristic to pure PPy. The Young's moduli generally increased with increasing of CNT content and values ranged from 2.67 GPa in the case of pure PPy to 4.15–4.61 GPa in the case of PPy/CNT-PABS composite system.In agreement with earlier results from the literature for conducting polymer organic coatings, the higher conductivity of material leads to a more efficient anticorrosion protection capability, our results exhibited an enhance of conducting features even for very low mass of CNT-PABS or CNT-CA loaded in composites coatings therefore, an improvement of anticorrosion protecting ability.     

Low Temperature Hall Effect Investigation of Conducting Polymer-Carbon Nanotubes Composite Network

Polypyrrole (PPy) and polypyrrole-carboxylic functionalized multi wall carbon nanotube composites (PPy/f-MWCNT) were synthesized by in situ chemical oxidative polymerization of pyrrole on the carbon nanotubes (CNTs). The structure of the resulting complex nanotubes was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The effects of f-MWCNT concentration on the electrical properties of the resulting composites were studied at temperatures between 100 K and 300 K. The Hall mobility and Hall coefficient of PPy and PPy/f-MWCNT composite samples with different concentrations of f-MWCNT were measured using the van der Pauw technique. The mobility decreased slightly with increasing temperature, while the conductivity was dominated by the gradually increasing carrier density.     

Polypyrrole/carbon nanotube composites: Molecular modeling and experimental investigation as anti-corrosive coating

In this work we present a computational method based on molecular mechanics (MM) and dynamics (MD), to predict mechanical properties of polypyrrole (PPy)/polyaminobenzene sulfonic acid-functionalized single-walled carbon nanotubes (CNT-PABS) and PPy/carboxylic acid-functionalized single-walled carbon nanotubes (CNT-CA) composites. Furthermore, experiments were carried out to assess the anticorrosive features of the PPy film and CNT-PABS and CNT-CA PPy reinforced composite coatings. Computational bulk models of PPy/CNT-PABS and PPy/CNT-CA were implemented at atomistic scale and composite coatings were grown in situ onto carbon steel (OL 48-50) electrodes. PPy, PPy/CNT-PABS and PPy/CNT-CA computational models and films were investigated concerning mechanical properties by using computational tools. The obtained films were assessed experimentally as anticorrosive materials using potentiodynamic measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results clearly confirmed that the CNT-PABS and CNT-CA are properly dispersed in the composite coatings and have beneficial effect on mechanical integrity. Moreover, the anticorrosion protecting ability of the composite coatings is significantly higher than the one characteristic to pure PPy. The Young's moduli generally increased with increasing of CNT content and values ranged from 2.67 GPa in the case of pure PPy to 4.15–4.61 GPa in the case of PPy/CNT-PABS composite system.In agreement with earlier results from the literature for conducting polymer organic coatings, the higher conductivity of material leads to a more efficient anticorrosion protection capability, our results exhibited an enhance of conducting features even for very low mass of CNT-PABS or CNT-CA loaded in composites coatings therefore, an improvement of anticorrosion protecting ability.     

Structural and optical properties of self-assembled polypyrrole nanotubes

Polypyrrole (PPy) nanotubes doped with camphorsulfonic acid (CSA) have been synthesized using self-assembly polymerization method. The average diameter of the resulting PPy nanotubes has been controlled by varying the dopant/monomer molar ratio. Formation mechanism of PPy nanotubes has been discussed at length. The formation of PPy nanotubes has been confirmed from the high resolution transmission electron microscopy (HRTEM) studies. FTIR studies depict that the “effective conjugation length” of PPy nanotubes increases with increasing CSA/Py molar ratio. UV-vis studies reveal the formation of polaron and bipolaron bands within the band gap of neural PPy, confirming the doping of PPy nanotubes with CSA. The optical band gap energy decreases with increasing CSA/Py ratio and also the thermal stability of PPy nanotubes gets enhanced with increasing dopant/monomer molar ratio.     

Electrochemical synthesis of functional polypyrrole nanotubes via a self-assembly process

We successfully electrochemically polymerized functional polypyrrole (PPy) nanotubes via a self-assembly process in the presence of methyl orange (MO). The influence of polymerization conditions, such as working electrodes and electrochemical polymerization time, on the tubular morphology was discussed. A fibrillar precipitate of MO formed via electric flocculation on the electrode in a neutral aqueous solution prior to the polymerization of pyrrole and acted as a template for the subsequent growth of PPy nanotube. The importance of the MO aggregation in the forming process of PPy nanotubes was revealed by the observation that no tubular structure of PPy formed in dilute MO aqueous solution. The PPy-MO nanotubes obtained showed a high conductivity and an ability to alter photochemically the electrical behavior. In addition, as-prepared PPy tubes could be converted to the corresponding carbonized tubes when they were subjected to thermal treatment under an inert atmosphere.     

Hierarchical polymer nanocomposite coating material for 316L SS implants: Surface and electrochemical aspects of PPy/f-CNTs coatings

Biocompatible nanocomposite coatings can be synthesized to offer improved surface properties for biomaterials and biomedical implants. Nanocomposite coatings containing polypyrrole (PPy) matrix reinforced with functionalized multi-wall carbon nanotubes (f-CNTs) were deposited on 316L SS substrates using electrochemical route. FT-IR, XRD, SEM, and TEM were employed to characterize the nanocomposite microstructure. High resolution imaging showed relatively uniform dispersion of the CNTs in the nanocomposite with a typical tubular structure. Micro-indentation tests revealed improvement in the hardness of the PPy/CNTs coatings. Measurement of the contact angle indicated enhanced surface wettability of the nanocomposite coatings. The corrosion behavior of 316L SS samples coated with PPy/CNTs was studied in SBF medium. The corrosion potential and the breakdown potential of coated 316L SS substrates shifted to more noble values as compared to uncoated 316L SS samples. The results suggest that incorporating CNTs as reinforcements in PPy coatings can provide enhanced properties in terms of surface hardness, biocompatibility, and corrosion resistance.     

Synthesis of silicalite-poly(furfuryl alcohol) composite membranes for oxygen enrichment from air

An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated. A facile procedure is demonstrated for controlling the morphology and thickness of PPy film by adding ethanol in the reaction system and a possible mechanism of the coating formation process is proposed. The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs. Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites. The method may provide a facile strategy for tailoring the polymer coating on carbon nanotubes (CNTs) for carbon-based device applications.     

A Facile Synthesis of Polypyrrole/Carbon Nanotube Composites with Ultrathin,Uniform and Thickness-Tunable Polypyrrole Shells

An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated. A facile procedure is demonstrated for controlling the morphology and thickness of PPy film by adding ethanol in the reaction system and a possible mechanism of the coating formation process is proposed. The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs. Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites. The method may provide a facile strategy for tailoring the polymer coating on carbon nanotubes (CNTs) for carbon-based device applications.     

Fixed‐bed column removal of chemical oxygen demand,anions, and heavy metals from paper mill wastewater by using polyaniline and polypyrrole nanocomposites on carbon nanotubes

This research endeavored to develop a new application of polypyrrole (PPy) and polyaniline (PAn) synthesized in the presence of ferric chloride and potassium iodate as oxidants and coated on carbon nanotubes (CNT). The removal of heavy metals, anions, and chemical oxygen demand from paper mill wastewater was compared when polyaniline, polypyrrole, and their nanocomposites with carbon nanotubes were used for this purpose. It was found that PPy/CNT and PAn/CNT could be used as effective adsorbents in the wastewater treatment. Also, the synthesized products were investigated in terms of morphology, molecular structure, and thermal stability by using scanning electron microscopy, Fourier‐transform infrared spectroscopy, and thermal gravimetric analysis. J. VINYL ADDIT. TECHNOL., 19:213‐218, 2013. © 2013 Society of Plastics Engineers     

Anticorrosion efficiency of zinc-filled epoxy coatings containing conducting polymers and pigments

The dependence of the corrosion-inhibiting properties of zinc-filled organic coatings on the nature of the conducting polymers and conducting pigments added and on the pigment particles’ surface coating with conducting polymer layers were investigated. The following materials were selected to examine the corrosion-inhibiting properties of the conducting polymers: polyaniline phosphate (PANI), polypyrrole (PPy), natural graphite, and carbon nanotubes. Conducting pigment combinations for application in coating materials were formulated by applying pigment volume concentrations (PVC) of 0.3%, 0.5% and 1%, which were completed with Zn dust to obtain pigment volume concentrations/critical pigment volume concentrations (PVC/CPVC) = 0.64. Such conducting pigment/zinc dust combinations represented corrosion inhibitors to be used as ingredients in protective coatings. Solvent-based 2K epoxy resin based coating materials containing the corrosion inhibitors so formulated were prepared to examine their anticorrosion properties. The pigmented coatings were subjected to laboratory corrosion tests in simulated corrosion atmospheres and to standardized mechanical resistance tests. The protective coatings so obtained exhibited a higher efficiency than coating materials containing zinc dust alone. The coating material containing carbon nanotubes at PVC = 1% and the coating material containing graphite coated with polypyrrole (C/PPy) at PVC = 0.5% emerged as the best zinc-filled coating materials with respect to their corrosion-inhibiting efficiency. Treatment with the conducting polymers had a beneficial effect on the coating materials’ mechanical properties.     

CNTs表面包覆PPy对PVC复合材料电导率的影响

为促进碳纳米管(CNTs)更为有效地应用于聚合物抗静电复合材料,采用原位聚合在CNTs表面生成聚吡咯(PPy)包覆层得到CNT-PPy,其组成通过傅立叶变换红外光谱分析和热重分析确认。CNT-PPy作为导电剂添加到聚氯乙烯(PVC)中制备PVC/CNT-PPy复合材料,对比分析PVC/CNT-PPy复合材料电导率的变化规律可得:PPy修饰CNTs可降低PVC/CNT-PPy复合材料中CNTs的逾渗阈值;当PPy包覆层在CNT-PPy中质量分数约为51.1%,CNT-PPy在复合材料中的质量分数为3%时,制得PVC复合材料的电导率可达到10–7 S/cm量级。由此可知,CNTs表面可控的PPy修饰量对PVC/CNTs复合材料抗静电性能起到显著的提升作用,为CNTs作为高性能导电剂应用提供更多的空间。     

Synthesis and characterization of coaxial silver/silica/polypyrrole nanocables

Double‐shelled coaxial nanocables of silver nanocables with SiO₂ and polypyrrole (PPy; Ag/SiO₂/PPy) were synthesized by a simple method. The thickness of the outer PPy shell could be controlled by the amount of pyrrole monomer. The silver nanocables encapsulated in the interior of the hollow PPy nanotubes were obtained by the removal of the midlayer SiO₂. By the silver‐mirror reaction, flowerlike Ag nanostructures could be formed on the surface of the Ag/SiO₂/PPy multilayer nanocable. The application of the as‐prepared Ag/SiO₂/PPy–Ag composites in surface‐enhanced Raman scattering (SERS) was studied with Rhodamine B (Rh B) as a probe molecule. We found that the composites could be used as SERS substrates and that they exhibited excellent enhancement ability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Facile synthesis and electrochemical capacitance of composites of polypyrrole/multi-walled carbon nanotubes

Composites of polypyrrole (PPy) and multi-walled carbon nanotubes (MWCNTs) were synthesized by a facile method involving one-step electrochemical deposition from a thin-layer of ionic liquid solution attached on a glassy carbon electrode. The morphology of the composites was characterized by field emission scanning electron microscopy, and the capacitance properties were investigated by cyclic voltammetry (CV). The charge-discharge behavior of the composites prepared in this work was examined by chronopotentiometry at a constant current density for multi-cycle scans. The results show that the PPy/MWCNT composites have a porous 3D nanostructure, with high specific capacitance (SC) of 890 F/g (for the mass of the PPy in the composites) calculated from CV at 2 mV/s in 1.0 M KCl. The stability of the composites in 1.0 M KCl electrolyte was also examined by multi-cycle CV and only 9% decrease of SC value was observed for the 1000 cycles.     

Highly Stretchable,Fast Self‐Healing,Responsive Conductive Hydrogels for Supercapacitor Electrode and Motion Sensor

Conductive hydrogels as potential soft materials have attracted tremendous attention in wearable electronic devices. Nonetheless, manufacturing intelligent materials that integrate mouldability, stretchability, responsive ability, fast self‐healing ability, as well as mechanical and electrochemical properties is still a challenge. Here, multifunctional conductive hydrogels composed of poly(vinyl alcohol) (PVA) and polypyrrole (PPy) nanotube are prepared using borax as cross‐linker. The existence of multicomplexation, entangled PVA chains, and interconnected PPy nanotubes, as well as extensive hydrogen bonding results in the fabrication of hierarchical network of PVA‐PPy hydrogels. PVA‐PPy hydrogels exhibit high stretchability (more than 1000%), multiresponsiveness, low density (0.95 g cm^?3), high water content (96%), and 15 s self‐healing features. Furthermore, the self‐healing supercapacitor electrode and motion sensor based on PVA‐PPy hydrogels demonstrate ideal performances. This facile strategy in this work would be promising to construct an excellent multifunctional soft material for various flexible electrode and biosensor.     

Field emission enhancement of polypyrrole due to band bending induced tunnelling in polypyrrole-carbon nanotubes nanocomposite

Polypyrrole–multiwalled carbon nanotubes (PPy–MWCNT) nanocomposites with high field emission characteristics have been fabricated by a very simple and effective in situ chemical polymerization technique that bypasses the need of de-agglomerating the MWCNT. Based on structural characterization, we have proposed formation of a three tier structure of PPy–MWCNTs composite with granular PPy on the top. Field emission studies, explained on the basis of band bending at the PPy–MWCNT interface, show drastic increase of field enhancement factor (∼4664) and low turn on field (1.7 V/μm), opening new possibilities of improvement of PPy/PPy–MWCNT composites.     

Electrodeposition of polypyrrole–titanate nanotube composites coatings and their corrosion resistance

Polypyrrole (PPy) films (2 μm) containing titanate nanotubes (TiNT) were deposited from 0.5 mol dm⁻³ pyrrole (Py) and 1 g dm⁻³ of TiNT in 0.1 mol dm⁻³ aqueous oxalic acid on 904 L stainless steel (SS) 0.1 mm thickness at 298 K. Electron microscopy showed that the nanotubes were adsorbed on the PPy surface and uniformly dispersed in the polymer matrix. The PPy/TiNT composite contained <10 wt.% titanates which showed an increase of 53% hardness compared with polypyrrole alone. The TiNT provide nucleation centres to catalyze the polymerization of pyrrole and can adsorb up to 240 mg g⁻¹ of the monomer. The corrosion rates for SS, SS/PPy and SS/PPy/TiTN composites, evaluated by linear sweep voltammetry and open-circuit potential measurements in 3% w/v NaCl, were 1.61, 0.008 and 0.004 mg dm⁻² day⁻¹, respectively, indicating that corrosion rates of stainless steel decreased by up to three orders of magnitude in the presence of the composite films.     

Enhancing the performance of polypyrrole composites as electrode materials for supercapacitors by carbon nanotubes additives

In the framework of this study, a facile method to obtain polypyrrole (PPy)/carbon nanotubes composites is presented. Chemical polymerization of PPy directly on the carbon nanotubes allows to obtain a homogenous distribution of the polymer. A low amount of carbon additive, varying from 1.5 to 5.5 wt %, is applied in order to prevent the decrease of capacitance value due to the presence of a low-capacitance component and, at the same time, to protect the electrode material from mechanical changes during cycling electrical measurements. The electrochemical properties, such as capacitance, its retention at different current loads, cycling stability, or self-discharge, are discussed. Improvement of electrochemical performances of the synthesized materials is observed mostly during cyclic stability measurements and at high current regimes. The obtained results confirm that the addition of only 3% of carbon nanotubes provides the best electrochemical performances as electrode materials for supercapacitor application. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48867.     

Novel route to pure and composite fibers of polypyrrole

An organic salt (FeAOT) is synthesized by the reaction of sodium 1,4‐bis(2‐ethylhexyl)sulfosuccinate (AOT) and ferric chloride. It is fabricated into fibers by manual drawing and electrospinning. Long polypyrrole (PPy) fibers are obtained for the first time by a vapor deposition reaction of pyrrole on the FeAOT fibers, and this technique is extended to the synthesis of PPy composite fibers with multiwalled carbon nanotubes (PPy–MWCNT fibers). The PPy and PPy–MWCNT fibers have a nanoporous morphology, a conductivity of 10–15 S cm^?1, and a tensile strength of 12–43 MPa. The electrochemistry and current–voltage characteristics of the PPy fibers are also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1490–1494, 2007     

Fabrication of carbon nanotubes/polypyrrole/carbon nanotubes/melamine foam for supercapacitor

The carbon nanotubes (CNTs) have been loaded on the melamine foam (MF) to form the composite (CNTs/MF) by dip‐dry process, then polypyrrole (PPy) is coated on CNTs/MF (PPy/CNTs/MF) through chemical oxidation polymerization by using FeCl₃·6H₂O adsorbed on CNTs/MF as oxidant to polymerize the pyrrole vapor. Finally, CNTs are coated on the surface of PPy/CNTs/MF to increase the conductivity of the composite (CNTs/PPy/CNTs/MF) by dip‐dry process again. The composites have been characterized by X‐ray diffraction spectroscopy, scanning electron microscopy and electrochemical method. The results show that the structure of the composites has obvious influence on their capacitive properties. According to the galvanostatic charge/discharge test, the specific capacitance of CNTs/PPy/CNTs/MF is about 184 F g^?1 based on the total mass of the composite and 262 F g^?1 based on the mass of PPy (70.2 wt % in the composite) at the current density of 0.4 A g^?1, which is higher than that of PPy/CNTs/MF (120 F g^?1 based on the total mass of the composite and 167 F g^?1 based on the mass of the PPy). Furthermore, the capacitor assembled by CNTs/PPy/CNTs/MF shows excellent cyclic stability. The capacitance of the cell assembled by CNTs/PPy/CNTs/MF retains 96.3% over 450 scan cycles at scan rate of 20 mV s^?1, which is larger than that assembled by CNTs/PPy/MF (72.5%). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39779.     

Evaluation of corrosion resistance of polypyrrole/functionalized multi-walled carbon nanotubes composite coatings on 60Cu–40Zn brass alloy

Polypyrrole/multi-walled carbon nanotubes (PPy/MWCNT) and its carboxylic functionalized (PPy/MWCNT-COO⁻) composite films were successfully electropolymerized by cyclic voltammetry as protective coating against corrosion on 60Cu–40Zn brass alloy surface. It yielded to strongly adherent and smooth nanocomposite films. Kinetics of the corrosion protection was investigated in 3.5 wt% NaCl solutions by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. The results showed that the presence of MWCNT in PPy coat considerably reduces the corrosion rate of 60Cu–40Zn brass alloy. The enhanced inhibition is most likely due to interaction between MWCNT and PPy. This in turn, improves the alloy passivation improvement and alters the permselectivity of the coating from anionic selectivity to the cationic selectivity. Moreover, PPy/MWCNT-COO⁻ functionalized nanocomposite provided higher corrosion resistance coating than PPy/MWCNT alone.