Hydroxyapatite dispersed sulphonated PEEK composite membrane: Synthesis, structural and mechanical characterization

Abstract

A synthetic composite material membrane was synthesized using Polyether ether ketone (PEEK) as a polymer matrix, reinforced with nano-Hydroxyapatite (nHAp) as the ceramic for intended use as a hip bone implant material. Notwithstanding its close resemblance with hip bone material, PEEK is chemically and biologically inert and comes with limited biocompatibility. HAp has chemical and crystallographic similarity with carbonated apatite like human bones. In the present work it was used as reinforcement with PEEK in varying weight percentages, of 2, 5, 8 and 10 to determine the optimum mix for application as a bio hip implant material. HAp reinforcement beyond 10 wt. % was not considered as it resulted in agglomeration and reduction in mechanical properties. The polymer was sulphonated to facilitate chemical interactions with the hydroxyl (-OH) group of HAp to overcome poor interfacial bonding between PEEK and nHAp. The sulphonation also reduced the chances of wear debris from implant site getting resorbed into the body. These synthetic composite samples were then characterized using techniques such as x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope and energy dispersive x-ray spectroscopy, to ascertain its conformity in structure and morphology. Mechanical tensile tests were also carried out to determine tensile strength, yield strength and elastic modulus of the composite membranes. The synthesized sample, with 8 wt. % of HAp reinforcement, demonstrated the most suitable properties. The work propounds a fresh approach towards synthesizing a composite membrane using Polyether ether ketone, subjected to sulphonation (SPEEK), for intended application as a hip implant. The superior surface wetting, obtained on account of sulphonation of PEEK matrix, facilitated more intimate contact with nano-hydroxyapatite (nHAp) reinforcements and assisted in establishing superior, homogeneous and improved mechanical properties throughout the membrane.