On the structure of high performance anticorrosive PMMA–siloxane–silica hybrid coatings

Environmentally compliant organic–inorganic hybrid coatings for efficient corrosion protection of metallic surfaces are potential alternatives to the current method based on chromate passivation. In this context PMMA–siloxane–silica (PMMA–SS) hybrid films were prepared using the sol–gel process from...

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Bibliographic Details
Published in:RSC advances 2015-01, Vol.5 (129), p.106754-106763
Main Authors: dos Santos, Fábio C., Harb, Samarah V., Menu, Marie-Joëlle, Turq, Viviane, Pulcinelli, Sandra H., Santilli, Celso V., Hammer, Peter
Format: Article
Language:English
Subjects:
Chemical Sciences
Coatings
Corrosion prevention
Corrosion resistance
Electrochemical impedance spectroscopy
Engineering Sciences
Ethanol
Ethyl alcohol
Material chemistry
Materials
Polymethyl methacrylates
Protective coatings
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Summary:Environmentally compliant organic–inorganic hybrid coatings for efficient corrosion protection of metallic surfaces are potential alternatives to the current method based on chromate passivation. In this context PMMA–siloxane–silica (PMMA–SS) hybrid films were prepared using the sol–gel process from the radical copolymerization of methyl methacrylate and 3-(trimethoxysilyl)propyl methacrylate followed by acidic hydrolysis and polycondensation of tetraethoxysilane (TEOS), under variation of the ethanol to H 2 O ratio (0.0–1.0). The structural properties of about 2 μm thick coatings, deposited by dip-coating onto carbon steel, were related with their corrosion protection efficiency. The correlation of data obtained by X-ray photoelectron spectroscopy, nuclear magnetic resonance and small angle X-ray scattering has shown for intermediate ethanol to H 2 O ratios the highest connectivity (∼83%) of the inorganic phase, bonded covalently to organic moieties, yielding a dense and homogeneous nanocomposite structure with high thermal stability, very good adhesion to the metallic substrate and excellent barrier properties. The electrochemical impedance spectroscopy measurements have shown for coatings prepared at intermediate EtOH/H 2 O ratios a high corrosion resistance of almost 10 GΩ cm 2 , which remained unchanged for more than 6 months in contact with 3.5% NaCl solution and more than 3 months exposed to an acidic NaCl environment.
ISSN:2046-2069
2046-2069
DOI:10.1039/C5RA20885H