Synthesis and Characterization of Polyvinyl Alcohol/Chitosan-Reinforced TiO2 Composite Coating on Biodegradable Magnesium Alloy

Abstract

In this research, we addressed the challenge of the rapid degradation of magnesium alloys, particularly AZ31B, which have great potential to be widely used in biomedical applications. To mitigate this issue, we developed a composite coating comprising polyvinyl alcohol (PVA), chitosan (CS), and titanium dioxide (TiO₂) nanoparticles, in order to enhance the corrosion performance of the magnesium alloy. Our approach involved chemically synthesizing TiO₂ particles (4-20 nm) and incorporating them into PVA and PVA/chitosan matrices at varying weight percentages, which affect the amino group. We employed x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) for comprehensive characterization, confirming the successful synthesis of TiO₂ particles and the formation of composite coatings. The XRD analysis revealed the rutile phase of TiO₂ particles with an average crystal size conducive to effective reinforcement, while SEM imaging showcased the spherical morphology of TiO₂ particles. FTIR spectroscopy further elucidated the chemical bonding among TiO₂, PVA, and chitosan, validating the composite’s structural integrity. Notably, atomic force microscopy (AFM) analysis demonstrated a significant reduction in surface roughness post-coating, indicating improved biocompatibility, a crucial factor in biomedical applications. Additionally, the hydrophobic nature of the PVA/TiO₂-based coating and the hydrophilic character of the PVA/TiO₂/CS-based composite coating were revealed through water contact angle measurements, offering versatile surface properties for different biomedical requirements. Furthermore, our investigation into the electrochemical behavior of the coated magnesium alloy in a 0.9% NaCl solution highlighted a notable enhancement in corrosion resistance. Potentiodynamic polarization (PD) characteristics, such as E_corr (− 1.51 to − 0.18 V) and I_corr 5.44 × 10^-7 A/cm², were observed, emphasizing the effectiveness of the composite coating in protecting the magnesium surface from degradation.