金属配合物催化合成聚酯酰胺

Poly(ester amide) is a type of synthetic polymers containing ester groups and amide groups on the backbone. On account of the characteristic of the polyester and polyamide, poly(ester amide)s can be used as biodegradable materials, thermal plastic elastermers, thermotropic liquid crystal materials and hyperbranched polymers, by finely tuning their microstructures. To date, the main route to poly(ester amide)s remains the polycondensation of diols, amino acid and diacid, or through polytransesterization of ester monomer containing amide group, under high temperature as well as vacuum conditions. However, the resultant poly(ester amide)s usually have low molecular weight and broad molecular weight distribution due to the transesterification under elevated temperature. Moreover, the random distribution of the ester and amide group along the backbone of poly(ester amide)s significantly affects the mechanical properties and degradable property of the materials and thus confine their application. To address this issue, we propose two pathways to achieve structure-regulated poly(ester amide)s, namely, the ring-opening polymerization of 2,5-morpholine-dione and the copolymerization of acid anhydride with aziridine to yield poly(ester amide)s, respectively. The project is to rationally design metal catalyst, through finely tuning the sterics and electronics of ancillary ligand, to achieve controlled polymerization for the synthesis of poly(ester amide)s.

聚酯酰胺是一类主链上含有酯基和酰胺基团的聚合物。由于兼具聚酯和聚酰胺的双重特性，聚酯酰胺可作为可降解材料，热塑性弹性体，热致液晶材料以及超支化聚合物在日常生活中扮演很重要的角色。虽然很多课题组都致力于聚酯酰胺合成方面的研究，但是其合成方法主要集中于氨基酸，二醇以及二元酸的熔融态共聚，或先合成含有酰胺基团的酯类前体，再通过缩聚方法来制备。这种方法通常需要高温以及减压条件下进行，在聚合反应中常常伴有酯交换反应发生，造成得到的聚酯酰胺聚合物通常分子量不高，分子量分布较宽。同时，聚合物主链上酯基与酰胺基的无归分布也影响了聚合物的力学性质等，严重的影响了聚酯酰胺的应用范围。本研究项目拟通过采用杂环底物开环聚合以及共聚合两种方法得到结构规整的聚酯酰胺。通过合理的设计金属催化剂，通过调节配体的空间位阻以及电子效应，使中心金属可以活化底物来实现聚合反应。

我们按原计划合成了四齿席夫碱配体以及相应的金属配合物，并新合成了SalanCrCl配合物，通过核磁共振氢谱以及高分辨质谱对它的结构进行了表征。制备了反应底物2-甲基吖丙啶，并研究了2-甲基吖丙啶与丁二酸酐的共聚反应。结果表明，2-甲基吖丙啶与丁二酸酐在室温下快速发生反应；加入金属配合物或季铵盐或有机碱对共聚反应的影响不明显。2-甲基吖丙啶与丁二酸酐反应得到醇溶性的聚酯酰胺低聚物，分子量不超过1000..探索了以配合物salanCrCl为引发剂，在丁二酰亚胺与环氧环己烷中的催化性质。研究表明，丁二酰亚胺在金属铬配合物的作用下可以使环氧环己烷发生开环反应，生成N-(2-羟基环己基）丁二酰亚胺。季铵盐的加入可以明显的提高反应的转化率；而温度对反应的产率影响不大。.salanCrCl配合物作为引发剂可以引发环氧丙烷与降冰片烯酸酐以及环氧环己烷与丁二酸酐的开环共聚反应。得到的聚合物中含有部分的醚建，初步的结果显示分子量在5000左右，分子量分布相对较窄（PDI =1.4）。