Formulation of a covalently bonded hydroxyapatite and poly(ether ether ketone) composite

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Colleges, School and Institutes


Spinal fusion devices can be fabricated from composites based on combining hydroxyapatite and poly(ether ether ketone) phases. These implants serve as load-bearing scaffolds for the formation of new bone tissue between adjacent vertebrae. In this work, we report a novel approach to covalently bond hydroxyapatite and poly(ether ether ketone) to produce a novel composite formulation with enhanced interfacial adhesion between phases. Compared to non-linked composites (HA_PEEK), covalently linked composites (HA_L_PEEK), loaded with 1.25vol% hydroxyapatite, possessed a greater mean flexural strength (170±5.4 vs 171.7±14.8MPa (mean±SD)) and modulus (4.8±0.2 vs 5.0±0.3GPa (mean±SD)). Although the mechanical properties were not found to be significantly different (p>0.05), PEEK_L_HA contained substantially larger hydroxyapatite inclusions (100–1000 μm) compared to HA_PEEK (50–200 μm), due to the inherently agglomerative nature of the covalently bonded hydroxyapatite and poly(ether ether ketone) additive. Larger inclusions would expectedly weaken the HA_L_PEEK composite; however, there is no significant difference between the flexural modulus of poly(ether ether ketone) with respect to HA_L_PEEK (p=0.13). In addition, the flexural modulus of HA_PEEK is significantly lower compared to poly(ether ether ketone) (p = 0.03). Ultimately, covalent linking reduces hydroxyapatite particulate de-bonding from the polymeric matrix and inhibits micro-crack development, culminating in enhanced transfer of stiffness between hydroxyapatite and poly(ether ether ketone) under loading


Original languageEnglish
Pages (from-to)1-13
Number of pages13
JournalJournal of Tissue Engineering
Early online date17 Dec 2018
Publication statusPublished - 1 Jan 2019


  • poly(ether ether ketone), hydroxyapatitie, composite, spinal fusion