Forming and Coating of Hydroxyapatite on PEEK Substrate for Orthopedic Implants

Polyetheretherketone (PEEK) has been increasingly employed in mechanical properties in terms of strength,
and PEEK can exhibit an elastic modulus closely to cortical bone (18 GPa). However, since PEEK is chemically inert with a hydrophobic surface, cell adhesion on the surface is one of the demerits. Therefore, the present research aims to improve cell adhesion on the PEEK surface by Hydroxyapatite (HA) coating. In this research, the pretreatment of the PEEK surface was performed by the sulfuric treatment. Then, coating of HA on the PEEK surface was performed via a wet chemical technique. In the wet chemical process, the concentration of calcium phosphate solution was varied from 1X to 2X. The soaking temperature and duration were set at 37, 60 C for 24, and 72 hours. The results revealed that the wettability of the PEEK surface could be enhanced with sulfuric treatment. Contact angle decreased from 94 to 0 degrees before sulfuric treatment and HA coating, which showed super wetting. The XRD pattern and calcium phosphate ratio of the wet chemical coated specimen confirmed that HA structure was formed on the specimen surface
which was operated under the proper wet chemical condition (1X_60C_24H). Furthermore, there was no significant change in the mechanical property of PEEK either before or after the whole process.