Amido bisphosphonic acid as anchoring agent and photopolymerization initiator onto zirconium oxide surface

The surface modification of metal oxides by grafting an organic molecule allows the development of new specific properties on demand. In this work, we demonstrate the modification of the Yttria Tetragonal Zirconia Polycrystal (Y-TZP), which is a ceramic widely used in dental implantology, by polymer grafting of the surface in a three-steps protocol for tuning the wetting properties. The first step involved the preparation of zirconia pellet by sintering followed by their surface activation. In the second step, the organic initiator bearing a tertiary amine such as the N,N-dimethylamino group capable of initiating a radical photopolymerization reaction, was grafted onto the surface through a bisphosphonic acid functionality. In the last step, two monomers, namely methyl methacrylate and styrene, were photopolymerized on the zirconia surface by blue light irradiation. The chemical steps were monitored and characterized by X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE) and Atomic Force Microscopy (AFM). Wetting properties to different polar and nonpolar liquids and surface energies calculated with the Van Oss theory were found to vary systematically depending on the type of functionalization and grafting. This methodology is very promising for surface tuning of the dental ceramic.