Development of new functionalized polymer multilayer coating systems and adaptation to additively manufactured degradableimplants with complex inner and outer contours

The objective of subproject 2 is to develop a biodegradable and biocompatible coating platform to achieve a delayed and controlled degradation of magnesium (Mg)-based biomaterials that meets regulatory requirements for coatings on medical implants. For this purpose, a functional composite multilayer coating with protective properties against Mg degradation will be developed, characterized, and applied to the complex surfaces of additively manufactured lattice-structured implants. Preliminary studies have shown that composite coatings consisting of polyelectrolyte multilayers (PEM) and wax layers represent a promising strategy for controlling the degradation of Mg-based biomaterials. These coatings form nanometer-thin, nano-smooth, and homogeneous layers, in which the PEM provides a stable, well-adhering matrix for the wax layer, which in turn acts as a hydrophobic barrier that limits the diffusion of water and corrosive species such as chloride ions. In this way, the coatings protect Mg materials from degradation. As an additional level of protection, a stepwise crosslinking of the polymer chains within the PEM will increase packing density and improve coating stability. This is expected to enhance resistance to the corrosive physiological environment and enable a gradual degradation profile of both the coating and the Mg biomaterial. The incorporation of corrosion inhibitors is envisaged as a further means to control the degradation rate. In addition, the PEM/wax composite coating will be used to modulate biocompatibility. This multi-level approach aims to develop a more robust and biocompatible barrier that improves the corrosion resistance of Mg alloys and ensures their safe application in biomedical environments.