Facile synthesis of hydroxyapatite nanoparticles by a polymer-assisted method: morphology, mechanical properties and formation mechanism

Synthetic hydroxyapatite (HA), is emerging as the most promising bioceramic material for orthopaedic applications due to its similarity to the inorganic matrix of living bone and teeth. The miniaturization of size and tuning of the morphology are an important factor for current biomedical research. Polymers are useful components in the formation of one-and zero-dimension nanosized materials. Rod-like assemblies of HA spherical nanoparticles of ~20 nm with nanopores can be obtained by a novel, one-pot polymer assisted hydrothermal synthesis using Ca(OH) 2 and NaH 2 PO 4 .2H 2 O precursors with the polymer PEO, in two different sizes without controlling the pH manually. The effect of the amount and the molecular weight of the polymer, mechanical properties and morphology were studied, and formation mechanism was proposed. The conclusion is supported by the results from X-ray diffractometry (XRD), Fourier transforms infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). With increasing the PEO content in the precursor solution, particle size can be decreased, and Young's modulus can be increased. The Young's modulus of HA synthesized using PEO are comparable with that of natural cortical bone. In addition, synthesized HA can be used as a biomaterial due to its uniform morphology, highly disperse particles of nano size and nanoporosity.