两亲性六臂星形聚合物PDLLA-b-PEO的合成及其受限结晶和胶束化行为  

Synthesis,confined crystallization and micellization of six-armed star-shaped Poly(D,L-lactide)-b-Poly(ethylene oxide) copolymer

作　　者：张凤波[1] 谢续明[1] 袁伟忠[2,3] 袁金颖[2] 

机构地区：[1]清华大学化工系高分子所 [2]清华大学化学系有机光电子与分子工程教育部重点实验室,北京100084 [3]同济大学纳米与生物高分子材料研究所,上海200092

出　　处：《中国科技论文在线》2011年第3期176-180,186,共6页

基　　金：高等学校博士学科点专项科研基金资助项目(200800030047);国家自然科学基金资助项目(20874056)

摘　　要：通过阳离子活性开环聚合和大分子酯化反应的两步法,合成两亲性的聚消旋丙交酯-b-聚氧乙烯(sPDLLA-b-PEO)六臂星形嵌段聚合物。通过差示扫描量热法(DSC)测定了聚合物本体结晶行为。结果表明,无定形链段PDLLA的引入和特定的星形结构,使得PEO链段的结晶受到限制,出现了冷结晶现象,并且最大结晶温度随着升温速率的升高而增加。通过偏光显微镜(POM)研究了六臂嵌段聚合物结晶形貌,发现六臂sPDLLA-b-PEO生长产生环带球晶。并且通过调控聚合物与溶剂的比例,以及聚合物膜的厚度,发现溶剂可以减小球晶生长中积累的应力,使环带结构消失;但六臂聚合物对于几何受限的响应性较强,到膜厚减小时,环带结构重新出现。最后,通过渗析的方法,用不同的溶剂制备尺寸不同的胶束。Amphiphilic six-armed star-shaped sPDLLA-b-PEO was synthesized by combination of ring opening polymerization and macromolecular esterification to investigate its confined crystallization and micellization behavior due to its novel structure.The composition and structure of star-shaped copolymer were characterized by 1H NMR,GPC and FT-IR.The bulk crystallization behaviors of sPDLLA-b-PEO were determined by DSC,and sPDLLA-b-PEO exhibited specific cold crystallization process due to chain end restriction from both the star-shaped molecular architecture and amorphous PDLLA block.Moreover,the maximum cold crystallization temperature was increasing with heating rates increasing.It was also found by POM that sPDLLA-b-PEO had banded spherulites.The band periodicity in the spherulites of the block copolymers in solution cast films changed with evaporation rate,and became larger or even disappeared.By means of dialysis,spherulitic micelles with different sized were obtained from different solvents.

关 键 词：六臂聚丙交酯-b-聚氧乙烯星形嵌段 受限结晶 溶剂效应 膜厚效应 胶束化 

分 类 号：O631.3[理学—高分子化学]