Corrosion resistance of layer-by-layer assembled polyvinylpyrrolidone/polyacrylic acid and amorphous silica films on AZ31 magnesium alloys

Abstract

A layer-by-layer (LbL)-assembled composite coating containing SiO₂ and a biocompatible polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) multi-layer, designated as SiO₂/(PVP/PAA)₅, was prepared on AZ31 Mg alloy via dip-coating. The surface morphology, microstructure and chemical composition of the coating were investigated using FE-SEM, FT-IR, XRD and XPS. The physical properties of the coating were characterized by scratch testing. The results demonstrated that the coating was amorphous and remarkably soft. PVP and PAA promoted the formation of Ca–P precipitates, and the amorphous silica film further enhanced corrosion resistance. The SiO₂/(PVP/PAA)₅ coating may be a promising surface modification for degradable Mg cardiovascular stents.