結晶-無定形雙團鏈式共聚物摻合體之特殊結晶行為研究

Morphology and Crystallization Behavior of the Binary Blend of Crystalline-Amorphous Diblock Copolymers

朱哲毅(Che-Yi Chu)

指導教授 ： 陳信龍

國立清華大學/工學院/化學工程學系/碩士(2007年)

https://doi.org/10.6843/NTHU.2007.00659

摘要

無(僅英文摘要)

關鍵字

摻合體 ； 共結晶

並列摘要

Recently the co-crystallization behavior in the binary blend of PEO-b-PB with different molecular weights has been studied ( Huang, Y.-Y.; Nandan, B.; Chen, H.-L.; Liao, C.-S.; Jeng, U.-S. Macromolecules 2004, 37, 8175. ). The co-crystallization observed represents a scenario where a kinetically driven process found in homopolymer crystallization may turn into a thermodynamically controlled process in the crystalline-amorphous systems. It will be of interest to extend this concept to explore the possibility of co-crystallizing two chemically different blocks (C and D) in the binary blends of A-b-C and A-b-D. The diblock components chosen should bear identical amorphous block to enhance the miscibility of the two copolymers.

Previous studies of the binary blend of PEO and PLLA70-75 homopolymers revealed that these two polymers were miscible in the melt state, but they did not co-crystallize. Furthermore, the previous studies on the binary blends of a short symmetric diblock copolymer and a long symmetric or slightly asymmetric diblock copolymer indicted that the short diblock could act as the cosurfactant for the long diblock copolymers. Consequently, we chose a symmetric PS-b-PEO (SEO) and a symmetric PS-b-PLLA (SLLA) to prepare the blends in which the two diblocks may mix intimately by such a cosurfactant effect. We then proceed to explore if the two chemically different crystalline blocks can co-crystallize. If they can not co-crystallize, then it will be of interest to explore the crystallization behavior of these two crystallizable blocks under the influences of intimate mixing and localization of the junction points at the interface. Such constraints may drastically impact the crystallization process. The PEO/PLLA mixture studied here may hence be considered as a spatially confined blend of polymer brushes.

Our results on the melt morphology of SEO/SLLA blends indicated that the PS blocks from these two copolymers mixed intimately in the PS lamellar microdomains in the melt. Furthermore, PLLA and PEO also formed a miscible mixture in the corresponding microdomains. Due to the intimate mixing and the restricted mobility of the junction points from the two copolymers, the crystallization behavior of PLLA was significantly perturbed compared with that of the corresponding homopolymer blends. In the SLLA-rich blends, a new entity exhibiting a melting point of ca. 100℃ was found to develop irrespective of the crystallization condition. This new species coexisted with the crystalline phases of PEO and PLLA, and was attributed to the crystallites formed by the co-crystallization of PEO and PLLA under highly restricted conditions.

並列關鍵字

SEO ； SLLA ； blends ； co-crystallization

參考文獻

New York, 2002.

3. Ikkala, O.; Brinke, G. Science, 2002, 295, 2407.

Macromolecules 1970, 3, 87.

5. Leibler, L.; Pincus, A. Macromolecules 1984, 17, 2922.

6. Hashimoto, T.; Koizumi, S.; Hasegawa, H.; Izumitani, T.;