Superior multifunctional polypyrrole anticorrosion coating modified by polydopamine decorated barium titanate nanoparticles on NiTi shape memory alloys

Abstract

The enhancement of corrosion protection capabilities through the use of conducting polymer coatings has become a necessity in order to safeguard metallic materials for biomedical purposes. In the present study, the hydroxylated barium titanate nanoparticles (BT-OH) were functionalized with polydopamine (PDA) to promote the dispersion of nanoparticles in a polypyrrole (PPy) matrix. The TEM analysis confirmed the formation of the PDA layer on the BT nanoparticles (BT NPs). Then, PPy coating was successfully electropolymerized on NiTi alloy in the presence of various concentrations (1, 3, 5, and 10 wt %) of PDA functionalized BT (PBT). The morphology, structure, and topography of PPy and composite coatings were investigated utilizing the field emission scanning electron microscope (FESEM), Fourier transforms infrared spectroscopy (FTIR), and atomic force microscope (AFM). Surface morphology analysis exhibited that the augmentation of the PBT nanoparticles changed it from cauliflower-like for PPy to nodular-like for composite coatings. Nano-indentation evaluations of the coatings have demonstrated that the hardness and elastic modulus of composite-coated NiTi was raised favorably by PBT enhancement, reaching 0.86 ∓ 0.2 (GPa) and 16.06 ∓ 3.23 (GPa) in PPy with 5 wt % PBT (PPy/5PBT), respectively. Electrochemical examinations demonstrated that PPy/5PBT coating revealed superb corrosion protection in Ringer solution, serving as a physical barrier and preventing the pitting corrosion of NiTi alloy. Finally, the constructive effect of PBT inclusion in the PPy coating on the corrosion performance of NiTi substrate was authenticated by lower Ni ion release from composite-coated NiTi compared with PPy coating.