L-乳酸和乙醇酸共聚物的直接合成与微结构分析  

Synthesis of Copoly (Lactic Acid/ Glycolic Acid) by Direct Melt Polycondensation and Microstructure Analysis of the Synthesized L-LA/GA

作　　者：兰平[1] 吕佳[1] 

机构地区：[1]嘉兴学院,浙江嘉兴314001

出　　处：《高校化学工程学报》2006年第6期951-956,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：浙江省嘉兴市科技计划项目(2006AY2013)资助。

摘　　要：采用直接法熔融缩聚制备L-乳酸(L-LA)和乙醇酸(GA)共聚物。先是以摩尔比为90/10的L-LA和GA为原料生成低聚物,然后L-LA和GA低聚物在双催化剂二水合氯化亚锡和对甲苯磺酸的催化下进一步反应。在反应中,未使用任何有机溶剂。反应最终产物的性能和结构通过核磁共振(NMR)、差示扫描量热(DSC)等手段进行表征。结果表明,GA显示了比L-LA更高的反应活性,聚合过程中可能通过酯交换减少了GA和LA嵌段长度,而且随着GA含量和反应时间的增加会使共聚物产生更多的消旋,并使结晶度下降。目前反应条件下进行了嵌段共聚而非随机共聚。结果也表明,相对分子质量较高的L-LA和GA共聚物是可以通过直接聚合在适宜的工艺条件下制得。A two steps direct copolymerization process was developed to synthesize the copoly （lactic acid/glycolic acid） -L-LA/GA. During which the first step is to produce oligomer and then the oligomer of lactic acid/glycolic acid is polymerized with binary catalyst of tin chloride dehydrate/p-toluenesulfonic acid. In this way, the direct synthesis of L-LA/GA without any organic solvent was investigated, and the properties and structures of the products-L-LA/GA were characterized by nuclear magnetic resonance （NMR）, differential scanning calorimetry （DSC） and others. It could be seen that GA shows higher reactivity in copolymerization than that of L-LA, and the transesterification can occur during polymerization which decreases the sequence lengths of GA and LA blocks. The racemization of copolymers can be promoted by increasing GA fraction and reaction time. The racemization and transesterification will result in to shorten the sequence length and decrease the crystallinity, which were verified by DSC measurements further. Present reaction conditions bring out sequential block copolymerization instead of random copolymerization of lactic acid with glycolic acid. The results also show that comparatively high molecular weight copolymer of lactic acid and glycolic acid can be prepared by direct copolymerization process proposed under appropriate process conditions.

关 键 词：乳酸 乙醇酸 熔融缩聚 直接法 微结构 

分 类 号：O632.33[理学—高分子化学] O631.5[理学—化学]