微波辅助壳聚糖接枝聚乳酸共聚物的合成及表征

在微波辅助下，以辛酸亚锡为催化剂、壳聚糖(CS)为大分子引发剂引发消旋丙交酯（D,L-LA）本体开环聚合制备了壳聚糖接枝聚乳酸共聚物。通过正交实验研究了微波功率、催化剂用量、反应温度和反应时间对聚合反应的影响，确定了最佳合成条件。并通过红外光谱、元素分析、核磁共振氢谱、X-射线衍射和热分析对接枝共聚物的结构与性能进行了表征。结果表明，在微波条件下，能快速、有效地合成预定结构的壳聚糖接枝聚乳酸共聚物；聚乳酸支链的引入，有效削弱了壳聚糖分子间和分子内较强的氢键作用，与相应的壳聚糖比较，共聚物的结晶性能下降，热分解温度降低；原料配比对共聚物的结构与性能有显著影响，随nD,L-LA/nCS糖环数值增大，共聚物中平均乳酰单元数逐渐增大，共聚物的结晶性能、起始分解温度逐渐下降。

Microwave-assisted synthesis and characterization of chitosan-graft-poly(D,L-lactide) copolymers

Using a new method—microwave-irradiation to get the chitosan-graft-poly(D,L-lactide)(CS-g-PLA) copolymer, the graft copolymerization was carried out by ring opening polymerization using stannous octoat (Sn(Oct)2) as catalyst without any organic solvent. In order to find the best reaction condition, the effection of different condition in copolymerization were studied by the orthogonality experiment, including power of microwave, dosage of Sn(Oct)2, reaction time and temperature. And the graft copolymers were characterized by FTIR, 1H-NMR, DSC, X-RD and TG. The results showed that microwave-assisted ring-opening polymerization can obtain the CS-g-PLA copolymer successfully and raipdly.Compared with chitosan, the grafting copolymerization has destroyed the original crystallinity of chitosan, the products’ onset temperature of degradation and thermal stability descended. The feed ratio(D,L-lactide /aminoglucoside units molar ratio) had a strong influence on the structure and properties of CS-g-PLA copolymer, higher feed ratios led to graft copolymer with higher average degree of polymerization of polylactide branch chains, and the lower crystallinity and onset temperature of degradation.