Electrocatalytic deposition and transformation of polypyrrole layers

Beck, F.; Oberst, M.

doi:10.1016/0379-6779(89)90497-9

Cited by 28 publications

(7 citation statements)

References 11 publications

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“…The electrolyte for electrodeposition at a smooth Pt-wire electrode (A = 0.5 cm2, 1 mm diameter) was: 0.1 M pyrrole, 0.1 M purified NBufiF4 and 0.035 M HzO [18-201. 1 mM NBufir was added as a catalyst [21,22]. The electrodeposition was performed galvanostatically at 0.5 mA cmP2 under Ar up to a nominal thickness [17] of d, = 10 pm.Thusinteraction with the base electrode via throughgoing pores was omitted [23].…”

Section: Methodsmentioning

confidence: 99%

Corrosion of synthetic metals

Beck

Michaelis

1991

Materials & Corrosion

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Intrinsically conducting polymers as polypyrrole or polythiophene are new materials which have found widespread interest in the last ten years. Acceptor type doping leads to a solid, which is well comparable to graphite salts. For any kind of practical application of these polymers, the problem of adequate long term stability under environmental conditions must be solved. There are only a few measurements of conductivity vs. time in the air to derive conclusions in this direction, e.g. for polypyrrole. For the first time we present results of a systematic research into the understanding of corrosion phenomena, which occur in aqueous eletrolytes at different pH. Polypyrrole is selected as a well established candidate for a synthetic metal. Layers at a nominal thickness of 10μm on platinum, doped with BF4− anions, were investigated in aqueous buffers in the pH‐range of 1–13. Corrosion was determined via the measurement of the residual redox capacities. The material corroded after a rapid electrochemical mechanism and a relatively slow chemical mechanism. Both processes involve the radical cationic centers (polarons) in the solid. The time constants varied from 102 to > 108 s. Our findings allow for a better understanding of corrosion and selfdischarge of polypyrrole. Other conducting polymers were found to corrode after the same mechanism.

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Section: Methodsmentioning

confidence: 99%

Corrosion of synthetic metals

Beck

Michaelis

1991

Materials & Corrosion

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“…It has been suggested that water might reduce the solubility of oligomers [38] and thus lead to faster deposition on the electrode. Some authors have proposed that water, owing to its higher dielectric constant (80 compared to 37 of acetonitrile), reduces the Coulombic repulsion between the radical cations [39][40][41][42][43] facilitating radicalradical coupling. Obviously, this opinion cannot offer a convincing explanation for other monomer-solvent systems, e.g., pyrrole in propylene carbonate (PC) [44], in which water has a detrimental effect.…”

Section: Electropolymerization Of Carbazole On Cfmes By Cyclic Voltammentioning

confidence: 99%

Electrolyte and solvent effects of electrocoated polycarbazole thin films on carbon fiber microelectrodes

2006

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Carbazole was electrochemically synthesized on carbon fiber microelectrodes (CFMEs) in different electrolyte and solvent media. The characterization of polycarbazole thin films formed on micron sized carbon fiber electrodes was performed by electrochemical methods (i.e., cyclic voltammetric measurements, solid state conductivity measurements (four point probe), spectrophotometric methods (ultraviolet/visible spectroscopy (UV-vis), ex situ spectroelectrochemistry, fourier transform infrared reflectance spectroscopy (FTIR-ATR)) and scanning electron microscopy (SEM). The best electrolyte and solvent in regards to yield, conductivity and charge for the electrografting was sodium perchlorate in acetonitrile, whose conductivity was 3.60 mS cm )1 , had a yield of 89% and had a charge of 5.50C. The effects of scan rate, feed ratio, supporting electrolyte and solvent type on the electropolymerization are discussed.

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“…Previous reports of electropolymerization in non-aqueous media noted that small amounts of water improved polymer growth [51–53]. This improvement was attributed to increasing the permittivity of the polymerization solution.…”

Section: Discussionmentioning

confidence: 94%

Poly (3,4-ethylenedioxythiophene) graphene oxide composite coatings for controlling magnesium implant corrosion

Catt

Cui

2017

Acta Biomaterialia

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Magnesium (Mg) is a promising biodegradable implant material because of its appropriate mechanical properties and safe degradation products. However, in vivo corrosion speed and hydrogen gas production need to be controlled for uses in biomedical applications. Here we report the development of a conducting polymer 3,4-ethylenedioxythiphene (PEDOT) and graphene oxide (GO) composite coating as a corrosion control layer. PEDOT/GO was electropolymerized on Mg samples in ethanol media. The coated Mg samples were subjected to various corrosion tests. The PEDOT/GO coating significantly reduced the rate of corrosion as evidenced by lower Mg ion concentration and pH of the corrosion media. In addition, the coating decreased the evolved hydrogen. Electrochemical analysis of the corroding samples showed more positive corrosion potential, a decreased corrosion current, and an increase in the polarization resistance. PEDOT/GO corrosion protection is attributed to three factors; an initial passive layer preventing solution ingress, buildup of negative charges in the film, and formation of corrosion protective Mg phosphate layer through redox coupling with Mg corrosion. To explore the biocompatibility of the coated implants in vitro, corrosion media from PEDOT/GO coated or uncoated Mg samples were exposed to cultured neurons where PEDOT/GO coated samples showed decreased toxicity. These results suggest that PEDOT/GO coating will be an effective treatment for controlling corrosion of Mg based medical implants. Statement of Significance Coating Mg substrates with a PEDOT/GO composite coating showed a significant decrease in corrosion rate. While conducting polymer coatings have been used to prevent corrosion on various metals, there has been little work on the use of these coatings for Mg. Additionally, to our knowledge, there has not been a report of the combined used of conducting polymer and GO as a corrosion control layer. Corrosion control is attributed to an initial barrier layer followed by electrochemical coupling of the PEDOT/GO coating with the substrate to facilitate the formation of a protective phosphate layer. This coupling also resulted in a decrease in hydrogen produced during corrosion, which could further improve the host tissue integration of Mg implants. This work elaborates on the potential for electroactive polymers to serve as corrosion control methods.

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Electrocatalytic deposition and transformation of polypyrrole layers

Cited by 28 publications

References 11 publications

Corrosion of synthetic metals

Corrosion of synthetic metals

Electrolyte and solvent effects of electrocoated polycarbazole thin films on carbon fiber microelectrodes

Poly (3,4-ethylenedioxythiophene) graphene oxide composite coatings for controlling magnesium implant corrosion

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