Preparation, Characterization and Morphology of Tapered Block Copolymers

以苯/四氢呋喃（50/50）为引发剂，在0℃条件下，用阴离子共聚法制备了苯乙烯和异戊二烯的锥形嵌段共聚物。基于气相色谱和核磁共振的分析表明，单体组成从链的一端到另一端逐渐变化。此外，对锥形嵌段共聚物进行臭氧化处理，以分解聚异戊二烯序列中的1,4-微观结构。臭氧分解产物的GPC分析结果证实产物链上有锥形区域。制备了两种不同链长的锥形嵌段共聚物和一种规则嵌段共聚物。用透射电镜和x射线小角散射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层状结构。

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.