【作者】 宋杰；

【导师】 闫玉华；

【作者基本信息】 武汉理工大学 ， 材料学， 2004， 硕士

【摘要】 聚乳酸(PDLLA)由于具有良好的生物相容性，可降解性，其最终降解产物为二氧化碳和水，由机体正常的新陈代谢排出体外，因此被广泛应用于手术缝合线、烧伤覆盖物，骨折内固定材料等。将其作为骨折内固定材料关键是要保证初始力学强度满足修复松质骨骨折的要求，对于合成高分子量聚乳酸工艺条件的研究是本论文的重点。 聚乳酸的制备方法主要有两种：直接缩聚法和开环聚合法。直接缩聚法制得的聚乳酸分子量低，而且分子量分布较宽。其力学性能不能满足生物医学上的某些要求。因此，目前制备高分子量聚乳酸(PDLLA)最常用的方法是开环聚合法，即通过D,L-乳酸合成丙交酯，再由丙交酯开环聚合形成聚乳酸。 本文采用开环聚合法由用D,L-乳酸合成PDLLA。该合成反应主要分为两步进行——丙交酯的合成和丙交酯的开环聚合。首先在催化剂ZnO的作用下减压脱水生成聚乳酸的低聚物，然后通过升高温度使低聚物裂解得到丙交酯，合成的丙交酯在辛酸亚锡催化作用下聚合得到PDLLA。 在合成丙交酯的过程中，通过对反应装置的改进，解决了丙交酯的堵塞问题，提高了丙交酯的产率；通过研究催化剂用量、脱水温度、脱水时间、脱水量以及解聚温度、解聚时间等对反应的影响，确定了合成丙交酯的最佳工艺条件。通过对粗丙交酯及提纯后的丙交酯进行性能表征，确定丙交酯的纯度及提纯工艺。对丙交酯聚合的影响因素进行了探讨，主要有本体纯度、引发剂用量、聚合温度、聚合时间、聚合的真空度等。经过对不同条件下合成的PDLLA分子量的测试，结果表明，通过控制聚合反应的条件可获得分子量较高的PDLLA，主要工艺参数为：引发剂与单体的质量比率为0.03％左右，聚合温度在140℃左右，聚合时间48h，聚合真空为0.05mmHg。更多还原

【Abstract】 The macromolecule poly-lactic acid ( PDLLA ) since there being the good compatibility and degradable, Hence widely having been used to the absorbing operation thread, burn cover and internal fixation of bone fracture. The second operation suffering may be avoided as filling the stuff inner place the fracture admittedly. But causing to poly-DL- lactide initial stage mechanics intensity fit the stuff demand admittedly, the key is how to improve the molecular weight.The preparing means of poly-lactic acid chiefly have immediate-condensation polymerization and the ring-open polymerization. Compared with these two method, The molecular weight by immediate-condensation polymerization is low but also the molecular weight distribute broadly, The stuff can not fit some mechanics performance admittedly, so, preparing high molecular weight PDLLA in common use is that the ring-open polymerization, that is, synthesis lactide by lactic acid and ring-open polymerization by lactide.Preparing degradable PDLLA by D,L-lactic acid in this paper. That reactchiefly to be divided into two steps--Preparing lactide and Ring-openpolymerization. First of the step is in the condition of vacuum and the action ofcatalytic agent--ZnO, Obtaining PDLLA by ring-opening polymerizationwhich initiated with Sn(Oct)2.In the first process, The apparatus modification react by means of adjust instrument, Resolve lactide jam, Moreover decrease much loss; Research the catalytic agent the amount to be used, Dehydration temperature, Dehydration time, Dehydration amount along with depolymerization temperature, depolymerization time which affect the reaction, Getting the optimum technology term of the reaction. Characterized lactide and purified lactide. Research in the purification process infrared spectrum and the melting point alternation. Discussing initiator the amount to be used, polymerization temperature, polymerization time and vacuum and so on that affect the molecular weight. According to the research, preparing the high-molecular weight lactic acid by means of the ring-open polymerization is feasible. The main parameters are: I/M about 0.03%, polymerization temperature 140℃, polymerization time 48h, vacuum 0.05mmHg.更多还原