钠、钾配合物的合成、表征及催化丙交酯开环聚合

发布时间：2018-04-24 17:34

  本文选题：开环聚合 + 钠配合物　； 参考：《中国科学技术大学》2017年硕士论文

【摘要】：近年来,生物可降解聚合物一直受到人们的广泛关注,其中,脂肪族聚酯由于具有良好的生物相容性、生物降解性以及优越的机械性能而备受关注。合成脂肪族聚酯的原料来源广泛,且得到的聚合物具有分子量可控、分子量分布窄等优点,已被广泛应用于手术缝合线、口腔植入物、药物载体、基因载体、组织工程、组织支架等领域。聚丙交酯(PLA)作为一种重要的生物可降解聚合物,其合成原料可从玉米、甜菜等自然作物中获得,并且最终降解为对环境无污染的CO2和H2O,因此具备广阔的应用前景。金属催化环酯开环聚合是合成聚丙交酯的一种有效方法,研究出高效的金属配合物催化剂具有重要的应用价值,这也是近年来该领域的研究热点。本论文合成和表征了各种配体配位的钠、钾配合物,研究它们在选择性催化外消旋丙交酯(rac-LA)开环聚合中的作用,并对催化剂结构和丙交酯的催化活性及立体选择性的关系进行了讨论。主要内容如下:第1章介绍了生物可降解材料的发展背景和金属催化丙交酯开环聚合的机理以及聚丙交酯的立体结构;并分类介绍了各种金属体系(铝、钙、镁、锌以及碱金属等)催化丙交酯开环聚合的研究进展。第2章介绍了 N,N-双齿配体配位的钠、钾配合物的合成、表征及催化rac-LA开环聚合。研究发现:在苄醇(BnOH)存在的条件下,此类钠和钾的络合物都能有效地催化rac-LA开环聚合,且活性相当高。聚合反应在较低单体催化剂比例时可控性很好,继续增大单体催化剂比例,聚合向着不可控方向发展。增大BnOH比例,聚合反应可控性增加;降低反应温度,催化剂催化聚合的立体选择性提高,-60 ℃条件下得到了 Pm值为0.66的聚丙交酯。第3章介绍了一系列2-苯并三唑取代的酚氧配体和冠醚为辅助配体配位的钠、钾配合物,在BnOH存在的条件下,这些配合物都能立体选择性地催化rac-LA开环聚合,且催化活性相当高。溶剂、单体催化剂比例以及温度都对催化剂催化rac-LA的立体选择性影响很大。当温度由20℃C降低到60℃时,Pm值由0.61增加到0.77。在甲苯中聚合,得到等规取向的PLA,而在CH2Cl3和THF中聚合,得到杂规取向的PLA。
[Abstract]:In recent years, biodegradable polymers have been widely concerned. Among them, aliphatic polyester has attracted much attention because of its good biocompatibility, biodegradability and excellent mechanical properties. The synthetic aliphatic polyester has been widely used in surgical suture, oral implants, drug carriers, gene carriers, tissue engineering and so on for its advantages of controllable molecular weight and narrow molecular weight distribution. Tissue scaffolds and other fields. Poly (lactide), as an important biodegradable polymer, can be synthesized from natural crops such as maize and beet, and finally degraded to CO2 and H _ 2O, which has no pollution to the environment, so it has a broad application prospect. Metal catalyzed ring opening polymerization of cycloesters is an effective method for the synthesis of poly (lactide). The study of metal complex catalysts has important application value, which is also a hot research field in recent years. In this paper, the coordination of various ligands with sodium and potassium complexes was synthesized and characterized. The role of these complexes in selective ring-opening polymerization of rac-lactide rac-LAs was studied. The relationship between catalyst structure, catalytic activity and stereoselectivity of lactide was discussed. The main contents are as follows: in Chapter 1, the development background of biodegradable materials, the mechanism of metal-catalyzed ring-opening polymerization of lactide and the stereoscopic structure of poly (lactide) are introduced. Zinc and alkali metals) as catalysts for ring-opening polymerization of lactide. In chapter 2, the synthesis, characterization and catalytic rac-LA ring-opening polymerization of sodium and potassium complexes coordinated by N-N-didentate ligands were introduced. It is found that in the presence of benzyl alcohol BnOH, the complexes of sodium and potassium can effectively catalyze the ring-opening polymerization of rac-LA, and their activity is quite high. The polymerization has good controllability when the ratio of monomer catalyst is low, and the polymerization is uncontrollable with increasing the ratio of monomer catalyst. When the ratio of BnOH was increased, the controllability of polymerization was increased, and the stereoselectivity of catalyst was increased by decreasing the reaction temperature. The poly (lactide) with pm value of 0.66 was obtained under the condition of increasing the ratio of BnOH and the stereoselectivity of the catalyst. In chapter 3, a series of 2-benzotriazole-substituted phenoxy ligands and sodium and potassium complexes with crown ether as auxiliary ligands are introduced. In the presence of BnOH, these complexes can stereoselective catalyze the ring-opening polymerization of rac-LA. And the catalytic activity is quite high. Solvent, monomer ratio and temperature have great influence on the stereoselectivity of rac-LA. When the temperature is reduced from 20 鈩，

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