Surface Modification Of Hydroxyapatite Nanoparticles And Research Of Its Reinforced HIPS, PP Composites

Hydroxyapatite has been widely used in biomedical materials because of its good compatibility and osteoconduction. The fabrication of nanocomposites can be used as high-loaded graft material with polymers. However, HAP nanoparticles can be aggregated easily. The interfacial adhesion strength with the polymer matrix is very weak as a result of their high polarity and great surface energy, which caused its organic combination with bioinert polymer materials to be greatly limited. In order to solve this problem, the grafting modification of HAP surface properties is developed through a transition phase to increasing the binding ability and interfacial compatibility between HAP and polymer matrix. Nowadays, because of the low grafting efficiency and grafted amount, the application of HAP nanoparticles has been limited in more fields.Surface-initiated Atom transfer radical polymerization (SI-ATRP) can trigger the appropriate polymer reaction by means of the initiated point on the material surface, then it will prepare the well-controlled polymer film and the construction. The weight of the polymer film can be controlled by adjusting the polymerization conditions. That is the reason why SI-ATRP is widely used in the nanocomposites based on polymers.High impact polystyrene (HIPS) is one of the general plastics with good mechanical properties. It can also be transferred from a bioinert material to a bioactive one when it added HAP nanoparticles. Polypropylene (PP) is one of the widely used thermoplastic resin which is cheap, green and convenient. However, the application of PP, to some extent, has been limited, because of the high crystal degree, low toughness and poor machining precision.In this paper, the surface of HAP nanoparticles has been successfully modified through SI-ATRP reaction. With this method, the amount of the polymer grafted could be well controlled by adjusting the initiator/monomer ratio. The fabrication of nanocomposites was made by adding the modified HAP (HAP-PS) to HIPS and PP, respectively, which enhanced the interfacial binding strength between inorganic phase and organic phase. The main findings were as follows,Firstly, HAP nanoparticles were synthesized via general precipitation and 2-bromoisobuturyl bromide (BIBB), which was react with the hydroxy on its surface directly to form ATRP initiator (HAP-Br). FT-IR, TGA and TEM were used to characterize the nanoparticles we got. Secondly, HAP-Br was used to initiate the SI-ATRP of Styrene (St) to prepare polymer grafted HAP (HAP-PS). The products were investigated by FT-IR, TGA and TEM. Thirdly, nanocomposite of HIPS reinforced by HAP-PS was prepared via solvent blending. DSC, SEM and other instruments were employed to investigate the material. Lastly, HAP-PS/PP nanocomposite was prepared by solvent blending with the modified HAP dispersed uniformly in PP. DSC, SEM, POM, ARES and other instruments were used to investigate the products.