PMMA-SiO2 Organic-Inorganic Hybrid Coating Application to Ti-6Al-4V Alloy Prepared through the Sol-Gel Method

Siloxane-poly(methyl methacrylate) (PMMA) hybrid was synthesized based on the sol-gel method and applied to Ti-6Al-4V through dip-coating. The structural feature of the hybrid was subjected to Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TG); its morphological properties were analyzed through scanning electron microscope (SEM), energy dispersive spectrometry (EDS), atomic force microscopy (AFM) and contact angle. The electrochemical behavior and corrosion resistance of both the hybrid coating and the uncoated substrate were investigated based on electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). Results showed homogeneous coating formation due to the rigid hybrid network formed during polymerization, hydrolysis and condensation reactions. This outcome suggested interaction between the organic (methyl methacrylate (MMA)) and inorganic (tetraethyl orthosilicate (TEOS)) phases, which was favored by the coupling agent (3-(trimethoxysilyl)propyl methacrylate (TMSM)). The S0M (PMMA-SiO2 hybrid Ti-6Al-4V coated alloy) film presented regular topography and adherence to the substrate. Electrochemical simulated body fluid (SBF) tests showed that the hybrid coating presented better barrier properties (168 h of the immersion time) than the uncoated substrate, fact that makes it an interesting material for anti-corrosive applications in biomaterials.