Improvement of Mechanical and Anticorrosion Coating Properties in Conducting Polymer Poly(Propyl Methacrylate) Embedded with Silane Functionalized Silica Nanoparticles

Abstract

An excellent new nanocomposite coating consisting of poly(propyl methacrylate) (PPMA), silanes and SiO2 nanoparticles (i.e., PPMA/silane/SiO2 blend) for aluminium alloy (AA7178) protection in natural seawater is investigated by electrochemical techniques. Three different silanes namely, ethyltriethoxysilane (EES), (3-glycidyloxypropyl)triethoxysilane (GES), and (3-aminopropyl)triethoxysilane (AES) were used to prepare functionalized SiO2 nanoparticles which are incorporated into PPMA to form PPMA/EES/SiO2, PPMA/GES/SiO2, and PPMA/AES/SiO2 nanocomposites. Electrochemical impedance spectroscopy (EIS) displayed a pronounced increase in the charge transfer resistance and potentiodynamic polarisation studies showed a significant decrease in the corrosion current for the investigated nanocomposites. The resultant nanocomposites performed as an excellent passivation layer which prevents the diffusion of ions and slows down the corrosion process due to the inclusion of silane functionalized SiO2 nanoparticles to PPMA. Scanning electrochemical microscopic (SECM) studies showed very lower corrosion current at the scratch of the PPMA-silane/SiO2 nanocomposite coated aluminium alloy. Field emission-scanning electron microscopy/energy dispersive X-ray (FE-SEM/EDX) analysis displayed the formation of corrosion products as the passive layer that hinders the dissolution of aluminium alloy. Mechanical properties of the coated aluminium alloy were found to be enhanced by the inclusion of functionalized SiO2 nanoparticles to PPMA which complimented the electrochemical studies.