Electrosynthesis and protection role of polyaniline–polvinylalcohol composite on stainless steel

doi:10.1016/j.porgcoat.2013.11.002

Progress in Organic Coatings

Volume 77, Issue 2, February 2014, Pages 403-411

https://doi.org/10.1016/j.porgcoat.2013.11.002 Get rights and content

Highlights

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PVA increased the electropolymerization rate of PANI on stainless steel surface.
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PVA improved the protection role of PANI for SS against general and pitting corrosion.
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PANI–PVA improved hardness and adhesion to surface but with less thermal stability.
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PANI–PVA passivates the SS surface and improved the passive oxide composition.

Abstract

Polyaniline–polyvinyl alcohol (PANI–PVA) composite has been electrodeposited on stainless steel surface from aqueous sulfuric acid solution of aniline monomer in presence of soluble PVA at different concentrations. The PVA increased the rate of electropolymerization where 4 g/L PVA formed a composite of 37 wt% PANI and 63 wt% PVA composition. The composite layer exhibited more adhesion to the steel surface in comparison with PANI layer but with less thermal stability. It has higher protection role for the stainless steel (SS) against general and pitting corrosion. It enhanced the passivation of the SS surface by increasing the thickness of oxide film and improving the composition.

Introduction

Improvement of the existing materials and developing new ones which are stronger, lighter, and more resistant to aggressive environments attracted much attention. The conductive polymers (CPs) are still of considerable interest and importance as components of corrosion-resistant coatings [1], [2], [3], [4], [5], [6]. DeBerry reported a change in the corrosion of stainless steel (SS) of the types 410 and 430 which have been coated with PANI. The corrosion rate of SS is reduced significantly as a result of a form of anodic protection provided by the coating [1]. Such anodic protection is due to the redox states of PANI which are able to maintain the native passive film on the metal surface. Hermas et al. [2], [3], [4], [5], [6] found that, the passive film of SS under CP layers has different characteristics than that formed by application of positive potential. However, porosity and anion exchange properties of CPs could be disadvantageous particularly when it comes to pitting corrosion caused by small aggressive anions such as chlorides. The protective properties of CPs are enhanced through blending with polymer binders. This can be represented by the higher protective properties of PANI-based composite film containing Prussian blue and hexacyanoferrate against pitting corrosion of SS in chloride-containing acid media in comparison with bare PANI film according to Galkowski et al. [7].

PANI has attracted considerable interest in the last few decades because it is one of the best candidates for the preparation of conducting polymer-based composites. It is stable in the normal atmosphere and significant progress has been achieved in the preparation of PANI forms able to be processed and several conductive composites of protonated PANI with insulating polymer have been reported [8], [9], [10]. The use of CPs in different matrices such as epoxy, polyvinyl alcohol (PVA) or polyacrylic (PA) blends [11], [12], [13], [14] is a good strategy for corrosion protection with the benefit of the expected enhanced mechanical properties of such blends [15], [16], [17], [18]. de Souza et al. used Raman spectroscopy to demonstrate electrochemical communication between iron and PANI in an acrylic blend coating [19]. PANI–PVA composite films of good quality have been obtained by Gangopadhyay et al. and showed an appreciable electrical conductivity at different temperatures [20]. Various conductive composites were prepared by chemical polymerization of aniline in the presence of several water soluble polymers and/or anionic surfactants under various polymerization conditions [21]. PVA is a well known water soluble polymer with high transparency, very good flexibility and wide commercial availability [22], [23]. Based on the above mentioned, the current work is aiming to investigate the ability of the electrodeposited PANI–PVA composite to protect stainless steel against pitting corrosion.

Section snippets

Materials and techniques

All chemicals and reagents were purchased from Sigma–Aldrich, Steinheim, Germany unless otherwise mentioned. Aniline (ANI) was distilled before use. The reagents, PVA of molecular weight 89,000–98,000 and sulfuric acid were used as received. Double-distilled water was used to prepare all solutions. Electropolymerization and electrochemical characterization were carried out using a computerized Autolab PGSTAT 30 potentiostat/galvanostat with GPES software. Scanning electron microscopy (SEM)

Electropolymerization of the composite

The stainless steel exhibited a free potential in the active state in 0.5 M H₂SO₄ solution at room temperature and by introducing of aniline monomer (0.2 M) to the solution, the steel potential shifted to noble side forming a self-passivated state. By applying cyclic voltammetry within a suitable potential rang, PANI electrodeposited easily on the electrode surface. Fig. 1 shows cyclic voltammogram of PANI formation which is characterized by the two redox peaks A and C corresponding to the redox

Conclusions

The PANI–PVA composite was electrodeposited on SS surface from sulfuric acid solution containing ANI monomer and dissolved PVA. Utilization of PVA enhanced the electropolymerization process and the thermal analysis proved the incorporation of large amount of PVA within the matrix of PANI. PVA increased the adhesion of PANI to the steel surface, but it decreased the thermal stability. It improved the protection role of PANI in the sulfuric acid and chloride solutions and enhanced the formation

Acknowledgments

This project was funded by Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, under Grant no. MS 12/452/431. The authors, therefore, acknowledge with thanks DSR technical and financial support.

References (31)

A.A. Hermas et al.
Electrochim. Acta
(2005)
A.A. Hermas et al.
Electrochim. Acta
(2005)
A.A. Hermas
Prog. Org. Coat.
(2008)
A.A. Hermas
Corrosion Sci.
(2008)
Y. Cao et al.
Polymer
(1989)
K.L. Tan et al.
J. Phys. Chem. Solids
(1991)
J.Y. Kim et al.
Synth. Met.
(2007)
Y. Cao et al.
Synth. Met.
(1992)
C.Y. Yang et al.
Synth. Met.
(1993)
S. Adhikari et al.
Synth. Met.
(2009)

Y. Li et al.

Synth. Met.

(2010)

Z. Zhang et al.

Synth. Met.

(2002)

B. Wessling et al.

Electrochim. Acta

(1999)

R. Gangopadhyay et al.

Synth. Met.

(2001)

T. Hino et al.

Synth. Met.

(2006)

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Corrosion defined as the deterioration of a material when it interacts with its environment is a global problem. Among the different strategies employed to combat corrosion, the use of coatings and corrosion inhibitors are the most popular. Coatings or corrosion inhibitors form a layer over the metallic substrate and protect it against corrosion. Polymers, both naturally occurring and synthetic have been tested for metal corrosion protection as replacement for the toxic inorganic and organic corrosion inhibitors. Interest in them stems from their availability, cost effectiveness, and eco-friendliness (especially for natural polymers) in addition to the inherent stability and multiple adsorption centers. However, it is found that most polymeric materials studied are moderate corrosion inhibitors. Several attempts such as copolymerization, addition of substances that exert synergistic effect, cross linking, blending, and most recently incorporation of inorganic substances in nano size into the polymer matrix have been made to improve the inhibition ability of polymers. In this review, the application of conducting polymers, polymer composites and nanocomposites for corrosion protection of different industrial metal substrates are explored based on reported experimental data and their mechanism of inhibition explained. Some identified drawbacks and future direction in this area have also been highlighted.

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Electrosynthesis and protection role of polyaniline–polvinylalcohol composite on stainless steel

Highlights

Abstract

Introduction

Section snippets

Materials and techniques

Electropolymerization of the composite

Conclusions

Acknowledgments

Electrochim. Acta

Electrochim. Acta

Prog. Org. Coat.

Corrosion Sci.

Polymer

J. Phys. Chem. Solids

Synth. Met.

Synth. Met.

Synth. Met.

Synth. Met.

Synth. Met.

Synth. Met.

Electrochim. Acta

Synth. Met.

Synth. Met.