Effect of the solvent on growth and properties of polyaniline-based composite films
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In this study, we report on the electrosyntheses of polyaniline (PAni) and PAni/magnetite nanoparticle (PAni/Fe3O4-NP) composite films by a potentiodynamic method from water and ethanol solutions. The aim of the study is to evaluate the effect of the solvent on the electrochemical growth of these films. The growth cyclic voltammograms and the mass change variation (Δm), determined by the electrochemical quartz crystal microbalance technique, show that the polymer growth rate is lower in ethanol than in water (Δm in water is ca. 50% higher than in ethanol after 30 voltammetric cycles). As a consequence, the films grown from ethanol show a more compact and uniform morphology, as we observed with scanning electron microscopy. Furthermore, the formation of oxidation products is inhibited in ethanol. The PAni/Fe3O4-NP composite films electrosynthesized in ethanol showed enhanced electrochemical response than the composite films grown from water. This is attributed to the better dispersion of the nanoparticles in this solvent and consequently in the polymer matrix, as confirmed by the Δm value and the spectroscopic characterization. We conclude that electropolymerization from ethanol solution provides high-quality PAni and PAni/Fe3O4-NP composite films; the electrochemical and morphological properties of these films suggest that their use for corrosion protection is promising.
KeywordsPolyaniline Magnetite nanoparticles Composite films Electropolymerization Solvent EQCM
G.T. Franco and L.H.E. Santos are respectively grateful to the São Paulo Research Foundation (FAPESP, Process: 2014/15477-0) and to the Brazilian National Council for Scientific and Technological development (CNPq, Process: 140669/2014-0) for their scholarships. A.J. Motheo is also thankful to CNPq for the financial support.
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