Swelling behavior of ordered miktoarm star block copolymer-homopolymer blends

被引:16
作者
Avgeropoulos, A
Dair, BJ
Thomas, EL
Hadjichristidis, N
机构
[1] MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA
[2] Univ Athens, Dept Chem, Ind Chem Lab, Athens 15771, Greece
关键词
miktoarm star block copolymers; binary blends; morphological transition;
D O I
10.1016/S0032-3861(02)00131-3
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
We report the morphological characterization of asymmetric miktoarm star block copolymers of the (PS-b-PI)(n)PS type where n = 2, 3 (denoted 2DB and 3DB miktoarm stars, respectively) and a symmetric super H-shaped block copolymer of the (PS-b-PI)(3)PS(PI-b-PS)(3) type (denoted SH) which were synthesized by anionic polymerization. The initial volume fraction of PS (phi(PS)) for each copolymer was 0.51-0.56, giving a lamellar morphology. Addition of homopolystyrene (hPS) with a molecular weight lower than the respective PS blocks in the neat materials lead to a transition from the lamellar structure to hexagonally packed cylinders. Addition of low molecular weight homopolyisoprene (hPI) on the other hand, only resulted in swollen lamellae even when the overall composition was highly asymmetric (80/20). Changes in the lamellar spacing as well as in the respective PS and PI layer thickness were measured by SAXS. The transition from lamellae to cylinders with increased PS content occurred without the observation of an intervening cubic morphology for the 2DB and 3DB miktoarm stars. However, blends with 30 and 35% hPS ((phi(PS))(total) = 0.68-0.70) with the super H-shaped block copolymer lead to the observation of lamellar-catenoid structures. (C) 2002 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:3257 / 3266
页数:10
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