环内酯的制备及表征

发布时间：2018-04-11 18:45

  本文选题：环内酯 + 乙交酯　； 参考：《天津科技大学》2017年硕士论文

【摘要】：环内酯聚合物因为具有良好的可生物降解性和生物相容性,已经被越来越多的人们所关注,但由于生产成本较高,很大程度上制约了它在实际生活中的应用。聚乙交酯和聚丙交酯是应用最多的环内酯聚合物,而作为其聚合反应单体的乙交酯和丙交酯的成本及产品性能对于环内酯聚合物的普及有着极其重要的作用。本文首先以羟基乙酸为原料,分别用熔融法和共沸溶剂法制备了乙交酯,通过控制变量法,研究了催化剂体系、催化剂用量、升温速率、解聚剂的分子量、解聚温度以及高沸点有机溶剂等反应条件对乙交酯产率的影响,然后采用不同的溶剂体系对乙交酯进行了纯化,在不同的温度下进行重结晶,制备出α晶型和β晶型的乙交酯,并通过熔点、红外光谱、核磁共振氢谱、X-射线衍射图、热分析图和偏光显微图对产物乙交酯进行了表征。实验研究结果表明,乙交酯合成的最佳条件如下:在高沸点有机溶剂聚乙二醇二甲醚(NHD)和四乙二醇二甲醚(TGDE)作为混合溶剂的条件下,解聚反应阶段升温速率为15℃/min,解聚温度为225℃时,乙交酯的粗产率可达91.61%;乙交酯纯化的最佳溶剂体系为乙酸乙酯与丙酮的体积比(3～9):1,总产率可达79.4%;通过偏光显微镜观察,发现α晶型为薄片状而β晶型为颗粒状,其中β3晶型更易形成二聚体,有利于发生聚合反应。另外,以L-乳酸为原料,采用熔融法和共沸溶剂法制备了 L-丙交酯,通过控制变量法,研究了催化剂体系、催化剂用量、缩聚反应时间和解聚温度等反应条件对L-丙交酯产率的影响,并研究了重结晶次数对L-丙交酯纯度的影响,最后采用酸碱滴定法测定了 L-丙交酯中微量水和乳酸的含量,通过熔点、红外光谱、核磁共振氢谱、X-射线衍射图和热分析图对产物L-丙交酯进行了表征。实验研究结果表明,制备过程中采用溶剂共沸法,L-丙交酯合成的最佳条件如下:催化剂氧化锌和辛酸亚锡的摩尔比为7:3,其用量为L-乳酸质量的1%,缩聚反应时间为4h,解聚温度为240℃时,L-丙交酯的粗产率可达89.57%;使用乙酸乙酯作为溶剂,当重结晶3次时,纯化L-丙交酯的产率和纯度最优。最后分别对乙交酯和L-丙交酯的制备过程进行了物料衡算,为乙交酯和L-丙交酯的规模化生产提供了一定的依据。
[Abstract]:Because of its good biodegradability and biocompatibility, cyclic lactone polymer has been paid more and more attention by people. However, because of its high production cost, its application in real life is restricted to a great extent.Poly (glycolide) and polylactide (poly (lactide)) are the most widely used cyclic lactone polymers. The cost and product performance of glycolide and lactide as monomers play an important role in the popularization of cyclic lactone polymers.In this paper, glycolide was prepared by melt method and azeotropic solvent method using glycolic acid as raw material. The catalyst system, amount of catalyst, heating rate, molecular weight of depolymerization agent were studied by controlling variable method.The effects of depolymerization temperature and high boiling point organic solvent on the yield of glycolide were studied. Then the glycolide was purified by different solvent systems and recrystallized at different temperatures to produce 伪 -crystalline and 尾 -crystalline glycolide.The product was characterized by melting point, infrared spectrum, H-NMR X-ray diffraction, thermal analysis and polarizing microscopy.The experimental results show that the optimum conditions for the synthesis of glycolide are as follows: under the conditions of high boiling point organic solvents polyethylene glycol dimethyl ether (NHDD) and tetraethylene glycol dimethyl ether (TGDED) as mixed solvents,The crude yield of glycolide can reach 91.61 when the heating rate is 15 鈩，

本文编号：1737215