Surface Modification Of Hydroxyapatite Nanoparticles And Performance Study Of Its Reinforced PCL Composites

In recent years, the preparation of bone repairing materials has been gradually become one of the most important tasks in chemical, medical and materials field. In order to integrate the performance of variety materials, great progress has been made and the idea of composites materials has been accepted widely in recently years. Due to the weak interfacial compatibility between hydroxyapatite and polymer matrix, the application of biocomposites also has been limited. To solve this problem, chemic grafting modification strategy has been developed. However, because of the low grafted amount and uncontrollable grafting efficiency, the application of hydroxyapatite has been limited in more fields.Atom transfer radical polymerization (ATRP) is a useful polymerization method for constructing well-defined block and graft copolymers on material surface to modify their surface properties. Furthermore, ATRP is widely applied to prepare polymers with predictable molecular weights and narrow molecular weight distribution for its advantage of controlled chain growth and multiplicity of monomers.In this paper, a novel strategy to modify hydroxyapatite nanoparticles (HAP) surface has been developed by combination of ATRP and ring opening polymerization (ROP). In this method, definite functional groups were introduced onto the HAP surface and the amount of the functional groups could be controlled by adjusting the initiator/monomer ratio. The preparation and characterization of HAP and modified HAP were studied. The main contents were as follows:1.HAP nanoparticles were synthesized via chemical precipitation firstly. Then, 2-bromoisobuturyl bromide (BIBB) was coupled to the surface of HAP nanoparticles directly to obtain ATRP initiator (HAP-Br). FT-IR, TGA, XRD and TEM were used to investigate the nanoparticles of HAP and HAP-Br.2.HAP-Br was used to initiate the ATRP of 2-hydroxyethyl methacrylate (HEMA) to get functionalized HAP (HAP-PHEMA). The ROP ofε-caprolactone (CL) was initiated by HAP-PHEMA to obtain high grafting ratio modified HAP. These products were characterized by 13C CP/MAS, FT-IR, TGA, XRD and TEM.3.Composite materials of polycaprolactone (PCL) reinforced by modified HAP nanoparticles were prepared via solvent blending. DSC, SEM and other instruments were employed to inverstigate the composite materials.