【作者】 谭军军；

【导师】 陈民芳；

【作者基本信息】 天津理工大学 ， 材料物理与化学， 2008， 硕士

【摘要】 羟基磷灰石(Hydroxyapatite,简称HAp或HA)是一种典型的生物活性材料,具有优良的生物相容性和生物活性。人体的骨骼和牙齿是纳米羟基磷灰石针晶(nano-hydroxyapatite,n-HA)有序排列于胶原纤维而组成的天然复合材料,具有天然的纳米组装结构和优良的力学性能。而这种三维有序的纳米自组装结构与无机液晶态极其相似。本文采用化学沉淀法制备高长径比的羟基磷灰石纳米颗粒,通过控制反应条件(温度、pH值、反应物浓度、Ca/P比值)和有机物或分散剂种类与添加量变化,调控n-HA的形状和尺寸,然后将其制备成分散性很高的溶胶态,通过溶胶中羟基磷灰石含量的控制,研究实现羟基磷灰石无机液晶态的条件,并对液晶现象进行了初步的观察。结果表明:以浓度为0.2mol/L的硝酸钙和磷酸铵溶液为原料,控制反应pH为8,温度为90℃,可制备出长200nm-500nm,直径20nm-30nm,长径比为15-20的n-HA。在常压化学沉淀条件下,纳米羟基磷灰石的生长规律为:随反应温度升高n-HA颗粒形状相似、尺寸增大,结晶度提高,而其它因素的影响不明显。分别采用明胶、低分子量聚丙烯酸钠、柠檬酸钠和六偏磷酸钠复合体系作为纳米羟基磷灰石颗粒的分散剂,通过对n-HA水溶胶对比显示:明胶对n-HA有独特的表面包覆作用而使其保持在水溶液有中一定的悬浮稳定作用;低分子量聚丙烯酸钠通过表面吸附也对n-HA产生一定的稳定作用;柠檬酸钠和六偏磷酸钠复合体系的分散效果最好,可制备出高度稳定n-HA溶胶体系。对柠檬酸钠和六偏磷酸钠为复合分散剂的n-HA溶胶浓缩后的体系进行了初步的液晶观察,当溶胶浓度为5%时没有双折射现象,达到10%时,双折射现象较弱,而其浓度达到20%,体系出现了比较显著的双折射现象,此时溶胶的凝胶化临界浓度为8%.更多还原

【Abstract】 Hydroxyapatite, (HAp or HA in short) a typical biomaterial, has excellent biocompatibility and bioactivity, and the bone and the teeth of we human being are natural composites composed of nano-hydoxyapatite, which is systematically organized in collagen fiber with excellent physical property. As we can see, this self-assembled three-dimension nano-structure is similar to that of inorganic liquid crystal.In this paper, HA particles (n-HA) with high aspect ratio were prepared by chemical deposition. The reacting temperature, pH, the concentration and Ca/P molar ratio of the materials, and the amountof diffierent dispensants determine the shape and size of n-HA and the quality of n-HA aqueous colloids;The conditions for prepartion of n-HA sol and its liquid crystal were studied by controlling the proportion of n-HA in sol. The results are as follows:HA nano particles, 200nm in length, 20-30nm in diameter, 15-20 in aspect ratio could be obtained by the reacting between Ca(NO3)2 and (NH4)PO4 solutions in 0.2mol/L concentration at 90℃, pH 8. As the reaction temperature goes, it was discovered that as the reaction temperature went high, the sizes of n-HA were enlarged and crystallinity is improved while the shapes were still very simillar to the original.Found out the proper dispersant such as Gelatin, low molecular weight Polyacrylate sodium, sodium citrate and sodium hexame taphospha for preparation of n-HA colloid. Compared with these dispersants for their stability and dispensilility, it is obvious that gelatin has a particular function of the coating n-HA and it has a certain function on the stability of HAp in aqueous solution; low molecular weight polyacrylate sodium, by chemical absorption on the surface, is also functional for the dispense of n-HA in solution; sol with good quality could be prepared by using sodium citrate and sodium hexame taphospha as multiplex dispersant.Inspection on liquid crystal state was carried out in the solution that was prepared by using sodium citrate and sodium hexame taphospha as multiplex dispersant, Gelatin respectively. It was found that the birefringence would be obvious when the non-volatile matter content of the sol was over 20%, when it was over 10% the birefringence would become less obvious, while below 5%, there would be no such phenomenon. It was also figured out that the concentration of gelatin is 8%, that is to say; the sol should be concentrated into gel state if there should be obvious phenomena of birefringence.更多还原