Deposition Of Polypyrrole Research Articles

Electrically conductive and hydrophobic cotton fabrics by polypyrrole-oleic acid coating

Hydrophobic polypyrrole-coated fabrics with improved electrical conductivity were produced embedding oleic acid as counter-ion. Hydrophobisation of polypyrrole was carried out by means of an ion exchange process after deposition of polypyrrole on cotton fabrics. The fabrics coated with oleic acid-doped polypyrrole showed contact angle of 111°, drop absorption time of 7 minutes and high water repellence, while electrical conductivity increased of ∼2 times and heat generation improved, too. Moreover, oleic acid demonstrated a great stability as counter-ion in polypyrrole matrix being present also after washing.

Colloidal Ni1−xCoxO nanostructures as anodic buffer layers in hybrid polypyrrole/Zn1−yInyO p–n junctions

The availability of a wide array of colloidal organic/inorganic nanostructures has opened up an interface to establish highly innovative and attractive hybrid materials for a number of optoelectronic applications recently. In this regard, a colloidal route has been established to fabricate hybrid photodiodes and study the influence of Ni1−xCoxO colloids as anodic buffer layers in them. The buffer oxide nanostructures were established through a facile surfactant free wet chemical approach with a cubic phase. Their absorbance properties were found to be influenced by the charge transfer process taking place between the O2− and Co2+ ions, while the vibrations corresponding to Co ions in between the tetrahedral and octahedral sites were found to be predominant in the Raman spectroscopy measurements. Hybrid p–n junctions were fabricated over the chemically in situ polymerized polypyrrole deposits using n-Zn1−yInyO and p-Ni1−xCoxO colloidal nanostructures through a drop casting methodology. The structural properties and distribution of the hybrid nanostructures across the heterostructures were perceived through Raman and scanning electron microscopy. The electrical properties of the fabricated hybrid heterostructures were assimilated using I–V characteristics, which revealed the interfacial anodic buffer layers to improve the charge selectivity across the corresponding electrodes by acting as efficient hole transporting layers (HTL) and blocking the flow of electrons.

Electrical properties and electromagnetic shielding effectiveness of polyester yarns with polypyrrole deposition

Polypyrrole was deposited on polyester yarns by vapour phase polymerization technique. Ferric chloride was used as an initiator. In order to determine the effect of the initiator concentration on polymerization process, four different initiator concentrations (0.2, 0.4, 0.6 and 0.8 mol/l) were used. The effect of the initiator in terms of tensile properties, electrical resistivities and morphological properties of the yarns was investigated. The polypyrrole deposited polyester yarns were then weaved in a handloom to form fabric for the investigation of surface resistivity and electromagnetic shielding effectiveness. Scanning electron microscopy, energy dispersive spectroscopy and Fourier transform infrared analyses illustrated that polypyrrole has penetrated into the yarn structure and the highest polypyrrole deposition was obtained at the initiator concentration of 0.6 mol/l. Also, the highest electromagnetic shielding effectiveness value and the lowest surface resistivity were obtained at this concentration.

Preparation and characterization of polypyrrole/clinoptilolite nanocomposite with enhanced electrical conductivity by surface polymerization method

AbstractIn this work, polypyrrole/clinoptilolite nanocomposite was synthesized by in situ surface polymerization of pyrrole using Fe3+ as oxidant, incorporated on the inner and outer surface of clinoptilolite nanoparticles. Formation of nanocomposite and deposition of polypyrrole on the clinoptilolite surface was confirmed and characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) patterns, scanning electron microscopy (SEM), and cyclic voltammetry techniques. Elemental analysis showed the loading/incorporation of 9.18 wt% polypyrrole in the clinoptilolite structure. However the electrical conductivity of polypyrrole/clinoptilolite nanocomposite pellets was higher than that of similar pure polypyrrole pellets, synthesized through the chemical oxidation polymerization method using Fe3+ as oxidant without the presence of clinoptilolite nanoparticles. Improved structural order or crystalinity of polypyrrole chains in nanocomposite structure which was confirmed by XRD and SEM results, may be the responsible of higher electrical conductivity of nanocomposite compared to pure polypyrrole although the low content (9.18 wt%) of polypyrrole in nanocomposite. Cyclic voltammetry studies showed that polypyrrole/clinoptilolite nanocomposite is electroactive similar to pure polypyrrole. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Influence of electrodeposition potential on composition and ion exchange of polypyrrole films in aqueous hexafluoroaluminate featured by EQCM molar mass to charge factors

EQCM gravimetry in a (10−8,10−6) g range was used for measurements of time processes of the potentiostatic deposition and redox state switching of polypyrrole in aqueous sodium hexafluoroaluminate. Time/potential dependencies of molar mass to charge factors determined from EQCM chronoamperometry and EQCM cyclic voltammetry were considered to reveal how the electrodeposition potential affects composition and ion-exchange properties of the resulting polymer film. Polypyrrole was synthesized at constant potentials, from +0.55V to +0.80V vs. SCE. The redox switching and accompanying ion-exchange were monitored in (+0.6,−0.6)V and (+0.6,−1.2)V vs. SCE potential windows.A lower mean chain length (polymerization degree) and a higher contribution of sodium in the mixed ion-exchange processes can be postulated for the thin polypyrrole deposit when it involves a higher content of the 2D chain packing structure. The distinct behavior corresponds to polypyrrole electropolymerized at the slowest rate, i.e. at +0.55V vs. SCE, which is know to result in the highest content of the 2D packing structure in the deposited film and the lowest mean reversible oxidation degree of the polymer.The molar mass to charge factor of EQCM gravimetry is useful for comparative studies of the rate processes involving electrolyte and electrode species, facilitating for their chemical identification.

Engineering of Complex Macroporous Materials Through Controlled Electrodeposition in Colloidal Superstructures

AbstractMacroporous materials with a sophisticated architecture are obtained by electrochemical deposition of gold or polypyrrole in colloidal‐crystal templates. The Langmuir–Blodgett technique enables assembly of sub‐micrometric silica‐particle monolayers on conductive gold substrates, thus leading to colloidal superstructures with an unprecedented control of their features at the single‐bead‐layer level. This allows the integration of deliberate planar defects or the elaboration of well‐defined gradients in terms of sphere size. Controlled infiltration using electrochemical deposition preserves the architecture of the original templates and leads to inverse opals with well‐defined pore structures after the removal of the inorganic particles.

Development of supercapacitor active composites by electrochemical deposition of polypyrrole on carbon nanofibres

In this study, pyrrole monomer is polymerized on carbon nanofibres (CNFs) via electropolymerization. This is a new technique to produce a chemically bonded CNF–polypyrrole composite. Deposition of the polypyrrole (PPy) on the nanofibres was optimized by varying the degree of deposition and deposition speed. Optimization studies have proven that the high deposition amounts result in blocks of polymers, which can be overcome through tuning the degree of polymerization by means number of cycles of electropolymerization and the scan rate of the electropolymerization.

Labelless impedance immunosensor based on polypyrrole–pyrolecarboxylic acid copolymer for hCG detection

In this work, a sensitive label-free impedimetric hCG-immunosensor was constructed by using a commercial screen-printing carbon ink electrode (namely disposable electrochemical printed chip) as the basis. The carbon ink electrode of DEP chip is modified first by deposition of polypyrrole–pyrole-2-carboxylic acid copolymer and thence hCG antibody immobilization via the COOH groups of pyrrole-2-carboxylic acid, which can serve as a linker for covalent biomolecular immobilization. The experimental results exposed that the designed immunosensor is more sensitive than other previously reported immunosensors, in the case of detection limit and linear range for antigen detection. With optimal fabrication parameters, the detection limit for α-hCG was 2.3pg/mL in 10mM phosphate buffer saline (PBS) solution containing 1% bovine serum albumine (BSA). Moreover, the use of inexpensive DEP chip as a basis for these immunosensors will allow for simple instrumentation, disposable and portable at low cost. This work also demonstrates a new approach to develop a sensitive and label-free impedimetric immunosensor based on screen-printed electrode for applications in clinical diagnosis.

Deposition of Polypyrrole Onto Bucky Gel for Use in a Biomimetic Artificial Excitable Cell Membrane

A novel and inexpensive bucky gel electrode was investigated for use as the electrode substrate for polypyrrole deposition. Potentiostatic deposition of polypyrrole onto gold and bucky gel electrodes was carried out at +1.2 V versus saturated calomel electrode for 1 h in a standard three-electrode electrochemical cell. The electroactive polypyrrole membrane was successfully deposited onto bucky gel, and its surface morphology studied using scanning electron microscopy. Given the bucky gel’s dual ability to both conduct electricity and ions, this work establishes the first step toward a semisolid ion-gating system to be used in further applications.

Fabrication and Interfacial Electronic Structure Studies on Polypyrrole/TiO<SUB>2</SUB> Nano Hybrid Systems for Photovoltaic Aspects

The progress in studying the interfacial electronic structures of the developing new class of hybrid organic/inorganic material systems have envisaged a new dimension into the field of photovoltaics, which could be of great help in understanding the nature of charge transfer in them. In this regard, electropolymerization of pyrrole monomers have been carried out at room temperature on the surface of TiO2 working electrodes (assisted by UV radiations) and their interfacial electronic structure has been studied as a function of the applied photo anodic potentials. The formation of polypyrrole deposits has been ensured using FT-IR and Raman spectroscopy. Surface analysis of the hybrid matrix revealed the tendency of polymer molecules to cover up the spherical surface of TiO2 nanoparticles that could help in improving the light absorption rate. Signals (bands) corresponding to pyrrole molecules observed in the ultraviolet photoelectron spectroscopy measurements have been correlated with the polaronic states formed and identified to shift as a function of the applied photo anodic potentials, revealing the decrease in work function of the hybrid system to take place (confirmed using cyclic voltammetry measurements). The decreasing trend in the work function elucidates the adjustment in electronic structure of the system (hybrid materials possessing smaller work functions are generally preferred for photovoltaic studies). The aforementioned behavioural aspects have been reasoned with the increase in overpotential values for polarization, from the decrease in up-take rate of the anionic dopant, which increases the current density values, thereby modifying the conductivity of the systems.

Covalently Cross-Linked Colloidosomes

Model poly(glycerol monomethacrylate)-based macromonomers have been used to prepare sterically stabilized polystyrene latexes by either aqueous emulsion or alcoholic dispersion polymerization, affording mean latex diameters of approximately 107 or 1188 nm respectively as judged by dynamic light scattering. Such PGMA50−PS latexes have appropriate surface wettability to stabilize 25−250 μm oil-in-water Pickering emulsions, depending on the latex concentration and oil type. Colloidosomes were formed by covalent cross-linking of the hydroxyl-functional stabilizer chains from within the oil droplets using a polymeric diisocyanate (tolylene 2,4-diisocyanate-terminated poly(propylene glycol) [PPG-TDI]. This oil-soluble cross-linker was confined within the oil droplets, allowing colloidosomes to be prepared at 50 vol % solids without any aggregation. The resulting microcapsules survive removal of the internal oil phase using excess alcohol, unlike the noncross-linked Pickering emulsion precursor. These observations confirm the robust nature of these covalently stabilized colloidosomes. A method for controlling the permeability of these colloidosomes by exploiting the solvent properties of binary oil mixtures has also been evaluated. Finally, microcapsule permeability has been explored via dye release experiments. Less permeable microcapsules can be obtained by deposition of polypyrrole onto the colloidosome exterior.

Electropolymerization of pyrrole on oxidizable metal under high frequency ultrasound irradiation. Application of focused beam to a selective masking technique

A novel masking technique against polymer deposition based on High Intensity Focused Ultrasound (HIFU) irradiation was developed for the first time. With this in mind, a variety of background salts were tested. Sodium salicylate was found to be the most effective electrolytic medium for pyrrole sonoelectropolymerization on copper as it leads to a very efficient passivating oxide layer preventing copper dissolution while enabling polymer formation independently from sonication. In such a medium, high frequency ultrasound greatly refines surface structure, and a slight increase in doping level is observed. Finally, it was proved that focused ultrasound increases copper dissolution in sodium oxalate electrolyte while preventing polypyrrole deposition. A selected zone on the copper substrate was thus irradiated by the focused ultrasound beam to protect it from polymerization. In a second stage, a self-assembled monolayer was deposited on this polymer-free area to create a surface biphased substrate. This type of masking technique can be proposed as an interesting alternative to lithography as it is easier to carry out and allows chemical waste reduction.

Thiol versus Selenol SAMs as Nucleation Enhancers and Adhesion Promoters for Plasma Polymerized Pyrrole on Copper Substrates

AbstractThe use of SAMs to enhance the deposition and growth of polypyrrole (PPy) thin films on a copper substrate by plasma‐enhanced chemical vapor deposition (PECVD) is described. The composition, ordering, and compactness of the monolayers is studied by XPS, PM‐IRRAS, and electrochemical techniques in order to determine their quality. Pyrrole plasma polymerization is carried out on SAMs and on bare copper to study the effect of the monolayer in the deposition process. AFM microscopy demonstrates that, because of the pyrrole‐terminated group, PPy nuclei deposit and grow preferably on the SAM‐modified surface. The PPy films deposited on SAMs show very good adhesion to a copper substrate, which makes them good candidates for new electronic components. magnified image

Synthesis and Characterization of New Adhesion Promoter for Grafting Conducting Polymer on Oxide Substrate

AbstractFor grafting polypyrrole layers on oxidic substrates, the synthesis and characterization of a new adhesion promoter 11‐(pyrrol‐3‐yl) undecyl trimethoxysilane (PyTMS) were described in this article. The oxidation potential of PyTMS was determined by cyclic voltammetry. The grafting behavior of such an adhesion promoter on oxidized surface and chemical deposition of polypyrrole over the modified oxidized surface were studied. The adsorbed layer on the oxidized substrates thus formed was determined by both contact angle measurements and X‐ray photoelectron spectroscopy. Chemical polymerization of terminal pyrrole moieties on such substrates yielded adhesive polypyrrole films, and SEM image showed that the morphology of the polypyrrole films was influenced by the experimental conditions.

Evaluation of the potential dependence of 2D–3D growth rates and structures of polypyrrole films in aqueous solutions of hexafluorates

Polypyrrole hexafluorosilicate, PPYSiF 6, and polypyrrole hexafluoroaluminate, PPYAlF 6, were found to follow the mixed 2DI–3DI kinetic model of electrodeposition in the potentials range (+0.80 V, +0.60 V) and (+0.95 V, +0.55 V) vs. SCE, respectively. The potentiostatic depositions of polypyrrole were performed on polycrystalline gold and on the single layer or bilayer polypyrrole films. Only in the case of the third layer deposition of PPYSiF 6 (on PPYSiF 6) at +0.6 V, the experimental current was found to fit better with the 2DP–3DI model. For electrodeposition of PPYAlF 6 on gold, a slightly better quality fitting with 2DP–3DP or 2DP–3DI kinetic models was observed only for some samples synthesized at 0.55 V. In general, contribution of the 2D structure in the polypyrrole deposits was observed to decrease with an increase of the polarization potential. Conclusions of the mathematical analysis of the current–time functions are in accordance with a texture of the outer surface of the polymer layers visible in SEM micrographs. The apparent rate constants of the lateral and outward growths of polypyrrole increase with potentials in (+0.55, +0.80) V range. Under assumption of the classical electrochemical kinetics law, the anodic transfer coefficients were found lower than 0.5. Values of the outward growth rate constant were of the order of 10 −8–10 −10 mol/(s cm 2); being approximately one order of magnitude higher for polypyrrole hexafluorosilicate than for polypyrrole hexafluoroaluminate. The lateral growth rates of PPYAlF 6 on gold were found to depend on the electrodeposition potential more significantly than the outward growth rate. An increase in the growth rates with the potential was observed to diminish/vanish at E > +0.80 V, probably due to concurrent degradation processes of polypyrrole chains. The analysis of the deposition currents was done under conditions of the masking double layer currents that were characterized by the relaxation times of the order of seconds or longer.

A self-powered and thermally-responsive drug delivery system based on conducting polymers

A simple self-powered drug delivery system was developed based on the galvanic cell mechanism, involving the direct deposition of a drug-contained polypyrrole (PPy) film on the one side of a titanium foil. After covering the other side with a eicosane-poly( l-lactide) (PLLA) blend film, it is interesting to observe that massive drug release only occurred when the release medium was heated to the body temperature. The methyltetrazolium (MTT) assay indicated that the system had good biocompatibility. Since titanium is one of the most commonly used load-bearing implant materials, it is expected that the present drug delivery system can find applications in titanium-related orthopaedic fields.

Electrodeposition and characterization of polypyrrole films on copper

In the present study, citric acid (CA), sodium acetate (SA) and sodium benzoate (SB) are used as electrolytes and compared in terms of easiness for polypyrrole deposition and film characteristics. Electrochemical measurements in the solution having these electrolytes with and without pyrrole demonstrate that copper can be efficiently passivated before PPy electrodeposition. This layer was sufficiently protective to inhibit further dissolution of the copper electrode and adequately conductive to enable the electropolymerization of pyrrole at the interface leading to the generation of an adherent polypyrrole film. The characterization of these coatings is carried out by cyclic voltammetry, UV–visible absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies. The performance of polypyrrole as protective coating against corrosion of Cu in both acidic and basic solutions is assessed by the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS).

Development and characterization of polypyrrole‐polylactide conductive open‐porous composites

AbstractIn this study, conductive porous composites were fabricated using the host substrate with an interconnected porous network, followed by the penetration and deposition of polypyrrole (PPy) to create a continuous conductive network. The open‐porous host substrate was processed using polylactide (PLA) with compression molding and salt leaching techniques. Three different salt contents were varied from 75 wt %, 85 wt %, and 90 wt %, which were referred to by their salt‐to‐polymer mass ratios of 3, 6, and 9, respectively. The porous network was made conductive by coating its interior surfaces through in situ polymerization of PPy using iron (III) chloride as the oxidant species. These porous composites were then characterized to analyze the relationships between their morphology and their physical, conductive, and mechanical properties. The mechanical properties were then fitted with numerically simulated results from finite element modeling (FEM). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Polypyrrole on self-assembled monolayers of a pyrrolyl lipoic acid derivative—electrosynthesis and polymer film characterization

The electropolymerization of pyrrole on gold modified by a self-assembled monolayer (SAM) of a pyrrolyl lipoic acid derivative was investigated in detail and the results compared to those obtained on bare substrates. Both under potentiostatic and potentiodynamic control, a slight blocking action of the underlying SAM could be observed for the initial stages of polymer growth but thereafter the electrochemical features were similar to those collected for polypyrrole (PPy) deposition on bare gold. The morphology and structure of PPy films formed on the SAMs were characterized by atomic force microscopy and X-ray diffraction, which revealed that those polymer properties are much more influenced by the electrochemical mode of preparation, than by the underlying SAMs. While, when compared to PPy on bare gold, no effect has been detected on thin layers deposited at constant potential, surface areas with rather irregular morphology, as well as a small but beneficial influence in inducing order on the first few layers of the polymer film, have been observed on similar films formed by cyclic voltammetry. The typical globular morphology of PPy has always been observed for relatively thick layers in which the redox behavior, analyzed by in situ AFM, showed an increase in volume of the polymer nodules upon reduction, largely due to the SAM reorganization induced by the applied potential.

Targeted Deposition of Antibodies on a Multiplex CMOS Microarray and Optimization of a Sensitive Immunoassay Using Electrochemical Detection

BackgroundThe CombiMatrix ElectraSense® microarray is a highly multiplex, complementary metal oxide semiconductor with 12,544 electrodes that are individually addressable. This platform is commercially available as a custom DNA microarray; and, in this configuration, it has also been used to tether antibodies (Abs) specifically on electrodes using complementary DNA sequences conjugated to the Abs.Methodology/Principal FindingsAn empirical method is described for developing and optimizing immunoassays on the CombiMatrix ElectraSense® microarray based upon targeted deposition of polypyrrole (Ppy) and capture Ab. This process was automated using instrumentation that can selectively apply a potential or current to individual electrodes and also measure current generated at the electrodes by an enzyme-enhanced electrochemical (ECD) reaction. By designating groups of electrodes on the array for different Ppy deposition conditions, we determined that the sensitivity and specificity of a sandwich immunoassay for staphylococcal enterotoxin B (SEB) is influenced by the application of different voltages or currents and the application time. The sandwich immunoassay used a capture Ab adsorbed to the Ppy and a reporter Ab labeled for fluorescence detection or ECD, and results from these methods of detection were different.Conclusions/SignificanceUsing Ppy deposition conditions for optimum results, the lower limit of detection for SEB using the ECD assay was between 0.003 and 0.01 pg/ml, which represents an order of magnitude improvement over a conventional enzyme-linked immunosorbant assay. In the absence of understanding the variables and complexities that affect assay performance, this highly multiplexed electrode array provided a rapid, high throughput, and empirical approach for developing a sensitive immunoassay.