Electrochemical synthesis and redox behaviour of polypyrrole coatings on copper in salicylate aqueous solution

The Influence of Carbon Nanotubes on the Protective Properties of Polypyrrole Formed at Copper

Protective polypyrrole films doped with dodecylbenzene sulfonate (DBS) were formed at copper, while carbon nanotubes (CNT) were incorporated within the polymer films with the DBS to give PPy-DBSCNT (polypyrrole films doped with DBS and incorporated CNT). The polymer films were deposited from a 0.05 M DBS solution at a pH of 6.0 at a thin polypyrrole film doped with tartrate, which served as a stable pre-layer. Low corrosion currents of 0.12 and 0.05 μA cm⁻² were estimated using Tafel analysis for the PPy-DBS and PPy-DBSCNT films, respectively, while a significant reduction in the concentration of Cu²⁺ ions from the corroding copper was observed for the polymer-modified copper. The corrosion protection properties were attributed to the doping of the polymer by the large and immobile DBS anions and possibly, by the larger anionic micelles that are formed at a DBS concentration of 9.8 mM in the pyrrole-containing solution. These dopants give a negatively charged surface that repels chloride anions. The additional protective properties afforded by the CNTs appear to be related to the morphology of the CNT-modified polypyrrole coatings, while the functionalized CNTs also provide a negatively charged surface.

Graphene-based anticorrosive coatings for copper

The present study was focused on the development of environmentally friendly graphene-based anti-corrosive coatings and understanding the effect of these coatings on the electrochemical corrosion behavior of copper.

Electrochemical preparation and characterization of polypyrrole/stainless steel electrodes decorated with gold nanoparticles

The electrosynthesis and characterization of polypyrrole(PPy)/stainless steel electrodes decorated with gold nanoparticles and the performance of the composite electrode for sensing applications is described. PPy films were grown in potassium perchlorate and sodium salicylate solutions under comparable electropolymerization conditions. Polymer films prepared in the presence of perchlorate ions exhibited worm-like structures, whereas columnar structures were obtained in salicylate-containing solutions. Voltammetric response of PPy films prepared in salicylate solutions was more reversible. PPy films were decorated with gold nanoparticles obtained by a double step potentiostatic electrodeposition routine that allowed fine control of deposit characteristics. Analysis of deposits was performed by means of SEM and confocal Raman spectroscopy. The electrocatalytic activity of the Au/PPy electrodes was assessed for the electro-oxidation of hydrazine and hydroxylamine. Results showed a successful optimization of the route of synthesis that rendered nanocomposite electrode materials with promising applications in electrochemical sensing.

Electrosynthesis of a polyaniline/zeolite nanocomposite coating on copper in a three-step process and the effect of current density on its corrosion protection performance

We describe electrosynthesis of a polyaniline/zeolite nanocomposite on copper and the effect of current density on its corrosion performance for the first time.

Effects of high frequency ultrasound irradiation on incorporation of SiO2 particles within polypyrrole films

This paper deals with the effect of ultrasound on polypyrrole/SiO2 composite film elaboration through various steps (particle dispersion, electrosynthesis). Experiments were carried out on stainless steel in phosphoric acid solution. An efficient method for dispersion of SiO2 particles prior to electropolymerization, based on low frequency irradiation (20kHz), was proposed. It was shown that mechanical effects of high frequency ultrasound (i.e. mass transfer improvement) led to enhancement of electropolymerization kinetics. Scanning electron microscopy imaging and glow discharge optical emission spectroscopy revealed localization of SiO2 particles in the outer region of the films as well as better incorporation of particles under high frequency ultrasound irradiation. Finally, anticorrosion behavior of formed films was investigated in sodium chloride solution by Open Circuit Potential and anodic polarization methods. The results showed that polypyrrole/SiO2 films elaborated under ultrasound irradiation exhibit the best protective performances.

Improvement of the stability of colloidal gold superparticles by polypyrrole modification

The colloidal gold superparticle (SP)/polypyrrole (PPy) core/shell composites were successfully prepared by oxidative polymerization of pyrrole monomer on the surface of poly(N-vinylpyrrolidone) (PVP)-grafted colloidal gold SPs. These core/shell composites showed strong catalytic activity and excellent stability. Control experiments indicated that the morphology and the thickness of PPy shell were controllable by adjusting the dosage of pyrrole monomer. Meaningfully, the resulting SP/PPy core/shell composites were quite stable in water, which could be stored for more than half a year without damaging their structures. As an example, we demonstrated the use of these composites as catalyst for the reduction of methylene blue (MB) dye with a reducing agent of sodium borohydride. The composites exhibited highly catalytic activity and long-term stability, implying promising applications of SP/PPy composites in catalysis.

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

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