【作者】 赖琛；

【导师】 唐绍裘；

【作者基本信息】 湖南大学 ， 材料学， 2006， 博士

【摘要】 羟基磷灰石生物活性陶瓷具有良好的生物相容性,植入体内不仅安全无毒,还能引导骨生长。因此,它主要用于人体硬组织(骨、牙)的修复和替换,也用于人工血管、气管等软组织及药物控释和输送载体,还是一种优良的生物化学吸附剂。尽管羟基磷灰石陶瓷材料具有良好的生物相容性和生物活性,但是其抗弯强度低、脆性大,在生理环境中抗疲劳性不高,只能应用于不承重或者仅承受纯压力负荷的环境中。本实验的目的是为了制备出高长径比的羟基磷灰石纳米线,从而增加羟基磷灰石生物陶瓷材料的柔韧性和强度。实验用反胶团——热液法在高温高压的密闭反应釜中,以十六烷基三甲基溴化铵/环己烷/正戊醇/水溶液形成的反胶团溶液来控制羟基磷灰石纳米材料的生长形态,制备了宽度为40~60nm、长度为2~3μm、平均长径比高达80的纳米线。EDS能谱研究表明,该羟基磷灰石的Ca/P为1.78,大于计量型HA的钙磷比(Ca/P=1.68),是富钙型羟基磷灰石,同时电子衍射图、高分辨二维晶格像展示了该材料是结晶完好并且无晶格缺陷或位错的单晶体。论文的第三章探讨了不同的表面活性剂体系、Wo(体系中水的物质的量与表面活性剂的物质的量的比)、Po(正戊醇的物质的量与表面活性剂的物质的量的比)、反应温度、反应时间和pH值等工艺条件对产物的形态、结晶度和成分的影响。最终确定了最适宜制备高长径比羟基磷灰石纳米线的反应条件。论文在第四和第五章中分别讨论了在反胶团体系中合成羟基磷灰石纳米线的机理、反胶团对材料形态控制机理、反胶团-热液法的反应动力学、在反胶团中晶体的成核和生长机理。结合透射电镜和扫描电镜技术表征了纳米线的微观结构。利用傅立叶变换红外光谱分峰技术对反胶团的微观结构进行了研究;采用31P的核磁共振探讨了在水核中反应物离子与表面活性剂分子之间的相互作用;采用紫外可见光技术研究了水和正戊醇含量对反应体系的影响。利用时间分辨荧光技术以Ru(bpy)32+作为荧光探针确定了在不同Wo,Po值下荧光衰减的曲线方程,并且求出了反映局部受限的程度的参数S。结果表明:在CTAB/环己烷/正戊醇/反应物溶液体系中,当Wo=10,Po=3时,探针Ru(bpy)32+的运动完全受到限制。从而提出了在水核中纳米线的形成和反胶团对其控制形态的机理:组成反胶团的表面活性剂分子与反应物中的PO43-之间有着强烈的作用,正是这种作用导致形成了表面活性剂分子——无定形核的复合体,从而使得反胶团之间发生定向、不可逆的融合,保证了仅在一维方向上生成纳米线。水和正戊醇的含量变化会影响到反胶团的形态、尺寸以及表面活性剂分子与反应物离子之间的作用,从而对在其中更多还原

【Abstract】 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更多还原