Rapid formation of hydroxyapatite layer on polyetheretherketone by vacuum ultraviolet irradiation and microwave heating techniques

Rapid formation of hydroxyapatite [Ca10(PO4)6(OH)2; HAp] layer on the polyetheretherketone (PEEK) substrate was examined by the combined techniques of vacuum ultraviolet (VUV) irradiation and microwave heating. The surface properties of PEEK substrate were modified by the formation of carboxyl group due to the VUV irradiation at room temperature in air, whereas the formation of HAp layer was encouraged by the microwave heating of surface-modified PEEK substrate in the HAp-dissolved solution. The optimization of the fabrication conditions was conducted by checking (i) the distance of VUV lamp to PEEK substrate (1–12 mm) and VUV irradiation time (0–120 min) for the surface modification of PEEK substrate, and (ii) the microwave heating temperatures (100 and 140°C) for the rapid formation of HAp layer on the PEEK substrate. When the PEEK substrate was surface-modified by the VUV irradiation for 120 min with the distance of VUV lamp to PEEK substrate kept being 1 mm, and then was microwave-heated in the HAp-dissolved solution at 140°C for 10 min, the thickness of the HAp layer on the PEEK substrate attained approximately 10 µm.