Preparation, Characterization and Morphology of Tapered Block Copolymers

以仲丁基锂为引发剂，以苯/四氢呋喃(50/50)为引发剂，在0℃的条件下，通过单体混合物的阴离子共聚反应合成了异戊二烯和苯乙烯的锥形嵌段共聚物。基于气相色谱和1H-核磁共振的分析表明，单体组成从链端逐渐变化到另一端。此外，对锥形嵌段共聚物进行了臭氧氧化，以分解聚异戊二烯序列中的1，4-微结构。臭氧分解产物的凝胶渗透色谱(GPC)分析结果证实，产物在链上存在锥形区域。合成了两种不同链长的锥形嵌段共聚物和一种规则的嵌段共聚物。用透射电子显微镜和小角X射线散射仪对其形貌进行了研究。三种共聚物的微相分离结构显示出几乎相同的交替片层结构。

Tapered block copolymers of styrene and isoprene were prepared by anionic copolymerization of monomer mixtures using sec-BuLi as an initiator in benzene/THF (50/50) at 0℃. Analyses based on both gas chromatography and ^1H-NMR indicated that monomer composition gradually varied from one chain end to the other. Furthermore, the tapered block copolymers were ozonized so as to decompose 1,4-microstructure in the polyisoprene sequences. The GPC analysis results of the decomposed products by ozonolysis confirmed that the products had tapered regions in the chains. Two tapered block copolymers with different chain lengths in the tapered region and one regular block copolymer were prepared. Their morphologies were investigated by transmission electron microscopy and small angle X-ray scattering. Microphase-separated structures of three copolymers were revealed to show almost the same alternating lamellar structure.