Study On The Synthesis Of Hydroxyapatite Nanowires With Reverse Micellae-Solovthermal Method And Its Mechanism

Hydroxyapatite has good biocompatibility. It is nonpoisonous and safe to transplant into the living body of human being and it can induce the growth of bones, therefore, it is mainly used as biomaterials to replace or repair human hard tissues such as bones or teeth in clinical applications. It can also be used as soft tissue, such as artifical trachea or blood vessel. In addition, it can be used to control the release and delivery of drugs. It is an excellent biochemical adsorbent. However, due to its low bending strength, low thoughness and low fatigue strength in physiological enviroment, hydroxyapatite bioceramics cannot be used for heavy load-bearing applications.In our experiments, we aimed at preparing long hydroxyapatite nanowires with high axial ratio to enhance the strength and toughness of hydroxyapatite bioceramic. Nanowires of 40~60 nm width and 2~3μm length were prepared in sealed vessel at high temperature and pressure. By the morphological control of reverse micellae which were consisted of CTAB, cyclohexane, n-pentanol and reactants solution, the axial ratio of nanowires reached 80.EDS patterns showed that the product was calcium-rich hydroxyapatite with a Ca/P ratio about 1.78 (Ca/P ratio of stoichiometric hydroxyapatite is 1.67). The high-resolution transmission electron microscopy (HRTEM) image exhibited which was dislocation-free and had good crystallinity. The selected-area electron diffraction pattern suggested the nanowire was single crystal. In chapter 3, we discussed the influences of technological conditions such as surfactant systems, values of Wo (molar ratio of water to surfactant) and Po (molar ratio of n-pentanol to surfactant), temperature, reaction time and pH values on the morphology crystallinity and composition of the final product. The optimic technological conditions for the preparation of HA nanowires with high axial ratio were determined in our experiments.In chapter 4 and 5, the general mechanism for the growth of nanowires and the morphological-control ability of reverse micellae was described. Furthermore, we presented the equations of crystal nucleation rate and growth rate in reverse micellae solution. The microstructure of reverse micellae was investigated by the peak-fitted technique in FTIR spectrum. The 31 P NMR results explored the interaction between reaction ions in the water nucleus and surfactant molecules. Moreover, the influences...