Electrochemical Study of a Hybrid Polymethyl Methacrylate Coating using SiO₂ Nanoparticles toward the Mitigation of the Corrosion in Marine Environments

• Main Authors: José Maya-Cornejo, Francisco J. Rodríguez-Gómez, Gustavo A. Molina, Juan Galindo-de-la-Rosa, Janet Ledesma-García, Ángel R. Hernández-Martínez, Rodrigo Esparza, Ramiro Pérez, Miriam Estévez
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Materials
• Subjects: pmma hybrid coating; sio₂ nanoparticles; scanning electrochemical microscopy; electrochemical impedance spectroscopy
• Online Access: https://www.mdpi.com/1996-1944/12/19/3216

The demand for hydrophobic polymer-based protective coatings to impart high corrosion resistance has increased recently. The increase of the hydrophobicity in a hybrid coating is a new challenge, for that reason and in order to protect a metallic surface of oxidant agents, a poly (methyl methacrylate) (PMMA) coating with the addition of a different amount of silicon dioxide (SiO₂) was developed. The hybrid coating was applied on a sample of stainless steel AISI 304 by the dip-coating method. The characterization of the coatings was determined by electrochemical impedance spectroscopy and with a scanning electrochemical microscopy. The best coatings were PMMA and PMMA + SiO₂ 0.01% that exhibits a real impedance in the Nyquist diagram of 760 and 427,800 MΩ⋅cm², respectively, and the modulus of the real impedance in the Bode diagram present values of 2.2 × 10⁸ and 3.3 × 10⁸ Ω⋅cm². Moreover, the phase angle presents constant values around 75° to 85° and 85° for the PMMA and PMMA + SiO₂ 0.01%, respectively. Moreover, the values of the real resistance for the PMMA + SiO₂ 0.01% coating present values in the order of Mega-ohms despite the coating exhibits an artificial defect in their surface. The contact angle test showed that the hydrophobicity of the hybrid PMMA + SiO₂ 0.01% coating is higher than that of the pure PMMA coatings. The hybrid PMMA + SiO₂ coatings developed in this work are a very interesting and promising area of study in order to develop efficient products to protect metallic surfaces from corrosion phenomenon.