Chemical synthesis and characterization of hydroxyapatite (HAp)-poly (ethylene co vinyl alcohol) (EVA) nanocomposite using a phosphonic acid coupling agent for orthopedic applications

A novel bio-analogue hydroxyapatite (HAp)-poly (ethylene co vinyl alcohol) (EVA) nanocomposite has been synthesized by a solution-based chemical methodology with varying HAp contents from 10 to 60% (w/w). The surface of HAp particles has been modified with 2-carboxyethylphosphonic acid in order to enhance the interfacial bonding interaction between HAp and EVA, and hence to improve the mechanical properties of the composite. The interfacial modification has been investigated through Fourier transform infrared absorption spectra (FTIR), X-ray diffraction (XRD) and thermal analyses. The surface morphology of the composite and the homogeneous dispersion of nanoparticles in the polymer matrix have been investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. The use of phosphonic acid coupling agent promotes the uniform dispersion of HAp particles in the polymer matrix with strong particle–polymer interfacial bonding, which leads to a significant improvement in mechanical properties of the composite. The cell viability test indicates that the HAp-EVA nanocomposite is cytocompatible. The developed HAp-EVA nanocomposite may be potentially used as bone substitutes.