Solvent Effect on the Aggregation Behavior of Rod-Coil Diblock Copolymers
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- 作者：Jie Zhang ; Weiran Lin ; Anhua Liu ; Zhenning Yu ; Xinhua Wan ; Dehai Liang ; Qifeng Zhou
- 刊名：Langmuir
- 出版年：2008
- 出版时间：April 15, 2008
- 年：2008
- 卷：24
- 期：8
- 页码：3780 - 3786
- 全文大小：371K
- 年卷期：v.24,no.8(April 15, 2008)
- ISSN：1520-5827
文摘
The water-induced aggregation behavior of rod-coil diblock copolymers based on poly(ethylene oxide) (PEO) andpoly{(+)-2,5-bis[4'-((S)-2-methylbutoxy)phenyl]styrene} (PMBPS), PEO104-b-PMBPS53, was investigated in thecommon solvent THF and in the selective solvent dioxane. Before adding water, PEO104-b-PMBPS53 stayed as singlepolymer chains no matter what conformation the PEO block took (i.e., either the random coil conformation in THFor the compact globule conformation in dioxane). The critical water content (~6 wt %) at which PEO104-b-PMBPS53began 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 fromthose in dioxane/water. Narrowly distributed spheres with Rh 
20 nm were observed in dioxane, whereas in THF,a bimodal distribution peaked at 3 and ~300 nm, was observed. The results from 2D wide-angle X-ray diffractionand polarized optical microscopy demonstrated that the PMBPS blocks packed in a parallel pattern upon aggregationin dioxane/water. The anisotropic disclike structures observed in THF/water also indicated the orientation of thePMBPS blocks upon forming aggregates in dilute solution.
20 nm were observed in dioxane, whereas in THF,a bimodal distribution peaked at 3 and ~300 nm, was observed. The results from 2D wide-angle X-ray diffractionand polarized optical microscopy demonstrated that the PMBPS blocks packed in a parallel pattern upon aggregationin dioxane/water. The anisotropic disclike structures observed in THF/water also indicated the orientation of thePMBPS blocks upon forming aggregates in dilute solution.