氨基酸衍生物介入的支化聚乳酸的合成、表征及药物传输特性研究

Compared with the linear polylactides with the same molecular weight, branched ones show unusual properties, such as low melt viscosity, good solubility and so on. However, there are some problems in the process of the synthesis of polylactide, such as more expensive comonomer, the metal contaminant, the time-consuming synthesis and so on, which limit its application. One-pot synthesis of the branched polylactide is achieved through the introduction of nontoxic and catalytical group into the branched agents, which speeds the pace of industrialization for branched polylactide in medicine and environment. The branched polylactides are synthesized via a one-pot copolymerzation of lactide with multihydroxyamino acid as branched agent and catalyst. The structure and properties of the obtained polymer are characterized. The effect of the catalytical part in the comonomer on the synthesis, the encapsulation of single guest molecular of mixed guest system and crystallographic properties of the polymer are researched, which broaden the scope of application.

和具有相同分子量的线形聚乳酸相比，支化聚乳酸具有特殊的流变和机械属性。然而，目前制备支化聚乳酸存在诸如支化单体昂贵、催化剂金属离子残留、合成步骤繁琐冗长等问题，限制其应用范围。向商品化或容易制备的支化单体中引入具有无毒、高效催化功能的官能团，从而实现无需外加(或加少量)催化剂一锅法制备支化聚乳酸的目的，可以加快其在医学、环境领域的工业化应用步伐。因此，本项目拟以多羟基氨基酸同时作为支化剂和催化剂，一锅法合成支化聚乳酸，对所得支化聚乳酸的结构和性能进行充分表征，阐明支化单体中具有催化功能部分对制备支化聚乳酸的影响，并在此基础上，研究支化聚乳酸结晶、包裹和降解性能，拓宽其应用范围。

目前，制备支化聚乳酸存在诸如支化单体昂贵、催化剂金属离子残留、合成步骤繁琐冗长等问题，限制其应用范围。本项目利用两种兼具支化和催化作用的含叔胺支化单体，一锅法合成了多种支化聚乳酸(BPLA)，并对其进行了充分的表征。通过荧光光谱、紫外-可见光分光光度、差示扫描量热等技术研究了支化聚乳酸的荧光性质、包裹性质及和线性聚乳酸共混后的结晶和机械性质，结果表明，叔胺赋予支化聚乳酸荧光特性，而且通过对支化聚乳酸空气氧化后，可以使支化聚乳酸的最大吸收和发射波长发生红移，且荧光效率增强；同时引入的叔胺使支化聚乳酸具有客体包裹能力，将支化聚乳酸和线性聚乳酸共混后，显著地改善了线性聚乳酸的结晶和机械性能，有助于开拓可降解聚乳酸的新应用领域。

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