Effect of Loop/Bridge Conformation Ratio on Elastic Properties of the Sphere-Forming ABA Triblock Copolymers under Uniaxial Elongation
Effect of Loop/Bridge Conformation Ratio on Elastic Properties of the Sphere-Forming ABA Triblock Copolymers under Uniaxial Elongation
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DOI：
10.1021/ma050720w
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发表时间：
2005-10
期刊：
影响因子：
5.5
通讯作者：
Yoshiaki Takahashi;Yihu Song;N. Nemoto;A. Takano;Y. Akazawa;Y. Matsushita
中科院分区：
文献类型：
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作者：
Yoshiaki Takahashi;Yihu Song;N. Nemoto;A. Takano;Y. Akazawa;Y. Matsushita
用一系列分子量几乎相同但桥部分不同的聚苯乙烯-b-聚异戊二烯-b-聚苯乙烯（SIS）和环状SI混合制备的成球三嵌段共聚物的拉伸行为进行研究。聚苯乙烯-b-聚异戊二烯-b-聚（2-乙烯基吡啶）样品也用作100%桥接参照。用小角X射线散射法研究的晶格变形可以用仿射变形很好地表示，与桥分数无关。通过IR二向色性检查的I段的宏观应力和取向函数也可以近似地由仿射变形表示，其中幅度与桥分数成比例。在应力-应变曲线中，在低应变下观察到小肩部。肩部的存在可以通过晶格的恢复力来解释，恢复力的大小取决于微畴晶格的规则性。结果表明，恢复力与中间嵌段链的桥率呈线性关系。
Elongational behavior of sphere-forming triblock copolymers is examined using a series of sample having almost the same molecular weight but different bridge fractions prepared by mixing polystyrene-b-polyisoprene-b-polystyrene (SIS) and the cyclic-SI. A polystyrene-b-polyisoprene-b-poly(2-vinylpyridine) sample was also used as a 100% bridged reference. The lattice deformation examined by SAXS can be well expressed by affine deformation, independent of the bridge fraction. Macroscopic stress and the orientation function of I segments examined by IR dichroism can be also approximately expressed by affine deformation, where magnitudes are proportional to the bridge fraction. In the stress−strain curves, small shoulders were observed at low strains. The presence of the shoulder can be explained by restoring force of the lattice, the magnitude of which depends on the regularity of the microdomain lattice. It is found that the restoring force linearly depends on the bridge fraction of the middle block chains i...