Solvent effect on the aggregation behavior of rod-coil diblock copolymers.
Solvent effect on the aggregation behavior of rod-coil diblock copolymers.
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DOI：
10.1021/la703888m
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发表时间：
2008-03
期刊：
影响因子：
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通讯作者：
Jie Zhang;Weiran Lin;Anhua Liu;Zhenning Yu;X. Wan;D. Liang;Qifeng Zhou
中科院分区：
文献类型：
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作者：
Jie Zhang;Weiran Lin;Anhua Liu;Zhenning Yu;X. Wan;D. Liang;Qifeng Zhou
研究了基于聚环氧乙烷 (PEO) 和聚{(+)-2,5-双[4'-((S)-2-甲基丁氧基)苯基]苯乙烯} (PMBPS)、PEO104-b-PMBPS53 的棒状线圈二嵌段共聚物在普通溶剂 THF 和选择性溶剂二恶烷中的水诱导聚集行为。在添加水之前，无论 PEO 嵌段采用何种构象（即，THF 中的无规卷曲构象或二恶烷中的致密小球构象），PEO104-b-PMBPS53 都保持为单聚合物链。 PEO104-b-PMBPS53 开始聚集的临界水含量（约 6 wt%）在两种溶剂中也相似，表明 PMBPS 主导聚集过程。然而，THF/水中聚集体的尺寸、尺寸分布和形态与二恶烷/水中的聚集体有很大不同。在二恶烷中观察到Rh约20 nm的窄分布球体，而在THF中，观察到双峰分布在3和约300 nm处达到峰值。二维广角 X 射线衍射和偏光光学显微镜的结果表明，PMBPS 块在二恶烷/水中聚集时以平行模式堆积。在 THF/水中观察到的各向异性盘状结构也表明了 PMBPS 块在稀溶液中形成聚集体时的取向。
The water-induced aggregation behavior of rod-coil diblock copolymers based on poly(ethylene oxide) (PEO) and poly{(+)-2,5-bis[4'-((S)-2-methylbutoxy)phenyl]styrene} (PMBPS), PEO104-b-PMBPS53, was investigated in the common solvent THF and in the selective solvent dioxane. Before adding water, PEO104-b-PMBPS53 stayed as single polymer chains no matter what conformation the PEO block took (i.e., either the random coil conformation in THF or the compact globule conformation in dioxane). The critical water content ( approximately 6 wt %) at which PEO104-b-PMBPS53 began to aggregate was also similar in both solvents, indicating that PMBPS dominated the aggregation process. However, the size, the size distribution, and the morphology of aggregates in THF/water were quite different from those in dioxane/water. Narrowly distributed spheres with Rh approximately 20 nm were observed in dioxane, whereas in THF, a bimodal distribution peaked at 3 and approximately 300 nm, was observed. The results from 2D wide-angle X-ray diffraction and polarized optical microscopy demonstrated that the PMBPS blocks packed in a parallel pattern upon aggregation in dioxane/water. The anisotropic disclike structures observed in THF/water also indicated the orientation of the PMBPS blocks upon forming aggregates in dilute solution.