Development of siloxane-PMMA coatings reinforced by carbon nanotubes and graphene for anticorrosive applications

Abstract

Using the sol-gel process organic-inorganic hybrid with addition of carbon nanotubes and graphene will be synthesized with the objective to obtain a siloxane-PMMA system that combines the properties of high transmission in the visible region, elevated electrical conductivity, high mechanical strength, thermal stability and excellent corrosion characteristics. For this purpose the synthesis parameters will be correlated with the structural features, thus allowing the optimization of the optical, electrical, thermal, mechanical and electrochemical properties of the nanocomposites. The siloxane-PMMA hybrids will be prepared from the radical polymerization of methyl methacrylate (MMA) with 3-methacryloxipropiltrimethoxisilane (MPTS) using the thermal initiator benzoyl peroxide (BPO), followed by hydrolysis and condensation of tetraethoxysilane (TEOS) catalyzed in acidic conditions. Different concentrations of functionalized carbon nanotubes and graphene oxide will be added to the organic and inorganic phase. The carbon nanostructures will be characterized by X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy. The structural analysis of the hybrids will be performed by nuclear magnetic resonance, X-ray photoelectron spectroscopy and Raman spectroscopy. For the thermal analysis thermogravimetry and differential scanning calorimetry will be applied. The mechanical properties of the hybrids will be studied by compression and hardness tests. To analyze the optical and electrical properties UV-vis spectroscopy and the Van der Pauw method will be applied, respectively. Polarization curves and electrochemical impedance spectroscopy will be combined with surface analysis, using scanning electron microscopy, atomic force microscopy and photoelectron spectroscopy to evaluate the efficiency of anticorrosive coatings after long-term exposure to aggressive media, and to verify the integrity of the coating in relation to roughness changes, presence of defects and species formed in the corrosive process.