噻吩系環境應答型硬桿-柔軟嵌段共聚物: 合成、形態與光物理性質之研究

Thiophene Based Stimuli Responsive Rod-coil Block Copolymers: Syntheses, Morphologies and Photophysical Properties

黃冠凱(Kuan-Kai Huang)

指導教授 ： 陳文章

國立臺灣大學/工學院/化學工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.10031

摘要

環境應答型嵌段共聚高分子因其具備對特定標的物之高靈敏度而受到廣泛應用。諸多研究中，更以共軛結構之硬桿-柔軟嵌段共聚高分子最受矚目，其可藉由外界環境微小變異有效操控材料之光電性質；且其自組裝能力亦因不同嵌段間之不互溶性及硬桿段π-π作用力影響，生成具新穎功能性之奈米構形。如此奈米構形進而對於材料之物理性質造成影響。然而環境應答型硬桿-柔軟嵌段共聚高分子結構與相型態對應於高分子光電性質之相關研究至今仍未趨完善。故本論文之研究目標著眼於合成環境應答型之噻吩系硬桿-柔軟嵌段共聚高分子，探討在不同環境下該材料高分子結構、微胞型態對於光電性質之影響。
本論文第一部份(第二章)為探討雙親性聚噻吩-聚甲基丙烯酸二甲基氨乙酯嵌段共聚高分子之合成、分子結構及其多功能感測特性。此新穎嵌段共聚物採原子轉移自由基聚合方式，製備不同長度之聚甲基丙烯酸二甲基氨乙酯鍊段(重複單元為43、65與124)，並藉溶劑組成、溫度與酸鹼值變化，探討微胞結構及其相應光電性質。其中重複單元為43之共聚高分子因溶液水相比例提升，微胞型態由球狀轉為囊狀。於溫度及pH值變化之水相系統中，微胞型態則為不同大小球型微胞，並呈可逆性變化，溫度從25 oC增加至55 oC, 微胞大小由80 nm 增加至 150 nm, 而在pH 4和pH12，微胞大小分別為220 nm和70 nm, 此變化可從動態光散射儀鑑定觀察。對應於光電性質，提升水相比例將誘使噻吩呈現不同程度的聚集使吸收光譜紅移；但對於溫度及pH值變化，吸收光譜並無太大改變，因此溫度及pH值並不會誘使噻吩的排列發生改變。
本論文第二部份(第三章)為探討雙親性聚二乙烯五己基噻吩-聚甲基丙烯酸二甲基氨乙酯嵌段共聚高分子之合成、分子結構及其多功能感測特性。此新穎嵌段共聚物採原子轉移自由基聚合方式，製備不同長度之聚甲基丙烯酸二甲基氨乙酯鍊段(重複單元為101、156與231)，並藉溫度與酸鹼值變化，探討微胞結構及其相應光電性質。其光學穿透度於20至70 oC 為一可逆性的變化。在不同pH值下，因聚甲基丙烯酸二甲基氨乙酯鍊段有不同程度的質子化，除了改變最低臨界溶解溫度(LCST)外，亦改變此共聚高分子之微胞大小。酸性條件下，質子化程度高，高分子溶解度增加因而提高LCST，且因聚甲基丙烯酸二甲基氨乙酯鍊段的排斥使微胞變大；反之，鹼性條件下，溶解度減少而降低LCST，且聚甲基丙烯酸二甲基氨乙酯鍊段的收縮使微胞變大。
以上噻吩系列的嵌段共聚高分子在光學性質及結構皆具有良好的環境應答性質，亦證明其在多功能感測功能應用方面的潛力。

關鍵字

聚噻吩 ； 環境應答 ； 硬桿-柔軟嵌段共聚物

並列摘要

Stimuli responsive block copolymers can provide a variety of applications due to their high sensitivity in detecting targeted species. Among of these studies, conjugated rod-coil block copolymers have attracted considerable attention because of their electronic and optoelectronic properties could be efficiently manipulated by minor perturbations of environmental stimuli. In addition, self-assembly of π-conjugated polymer based block copolymers leads to various nanoscale morphologies driven by inherent immiscibility between different blocks and the packing constrains imposed by the π-π interaction of the conjugated segment. Such morphological transformation results in the variation of their physical properties. Regioregular poly(3-hexylthiophene) is one of the widely studied π-conjugated polymer with high environmental stability, good optical and electronic property. However, the effects of molecular architecture and photophysical properties of poly(3-hexylthiophene) based rod-coil block copolymers with multifunctional sensory characteristics have rarely been explored. In this thesis, new poly(3-hexylthiophene) based rod-coil block copolymers bearing stimuli responsive coil blocks were synthesized to explore the effects of polymer structure and morphology on photophysical properties in different enviroment.
In the first part of this thesis (chapter 2), the synthesis, structures and multifunctional sensory properties of amphiphilic poly[3-hexylthiophene]-block-poly[2-(dimethylamino)ethyl methacrylate] (P3HT-b-PDMAEMA) rod-coil diblock copolymers are reported. The new copolymers, with PDMAEMA coil lengths of 43, 65 and 124 repeating units, were synthesized by atom transfer radical polymerization (ATRP). The surface structures and photophysical properties of the synthesized polymers were studied through the variation of temperature, pH, and solvent composition (THF/water). The P3HT20-b-PDMAEMA43 structure changed from spheres to vesicle as the solvent composition changed from 0 to 100 wt% water. The micellar aggregates of P3HT20-b-PDMAEMA43 in water showed a reversible sphere size transformation from 80 nm to 150 nm on heating from 25 to 55 oC, and the micelle size also exhibited a transformation from 70 (pH = 12) to 220 nm (pH 4). The variation of the micelle size with temperature and pH was judged by dynamic light scattering (DLS) measurements. The intermolecular P3HT aggregations led to a red-shift on the absorption spectra of the block copolymer as the water content increased. However, the temperature or pH values did not affect the abosprtion spectra significantly.
In the second part of this thesis (Chapter 3), the synthesis, structures and multifunctional sensory properties of amphiphilic multifunctional sensory properties and morphologies of poly[2-vinyl-5-hexylthiophene]-block-poly[2-(dimethylamino)ethyl methacrylate] semirod-coil diblock copolymers are reported. The new copolymers, with PDMAEMA coil lengths of 101, 156 and 231 repeating units, were synthesized by atom transfer radical polymerization (ATRP). The photophysical properties of the synthesized polymers were studied through the variation of temperature and pH. The optical transmittance observed during the heating-cooling cycle of 20-70 oC suggested the thermo responsive behavior of PVT-b-PDMAEMA was reversible. The LCST of the PVT20-b-PDMAEMA45 decreased with an increasing pH, depending on the protonation to the PDMAEMA block. The micelle diameter reduced upon increasing pH 4 to pH 12 was probably due to the suppressant electrostatic repulsion on the charged PDMAEMA chains in the corona.
The above thiophene based rod-coil diblock copolymers exhitited multifuncation stimuli responsive characteristics on the morphology and photophysical property, which suggested their potential application on sensory devices.

並列關鍵字

Polythiophene ； Stimuli Responsive ； Rod-coil Block Copolymers

參考文獻

[8] (a) Lin, C.-H.; Tung, Y.-C.; Ruokolainen, J.; Mezzenga, R.; Chen, W.-C. Macromolecules 2008, 41, 8759. (b) Ma, Z.; Qiang, L.; Zheng, Z.; Wang, Y.; Zhang, Z.; Huang, W. J. Appl. Polym. Sci. 2008, 110, 18. (c) Xiao, X.; Fu, Y.-Q.; Zhou, J.-J.; Bo, Z.-S.; Li, L.; Chan, C.-M. Macromol. Rapid Commun. 2007, 28, 1003. (d) Yang, C.-C.; Tian, Y.; Jen, A. K.-Y.; Chen, W.-C. J. Polym. Sci. Pol. Chem. 2006, 44, 5495. (e) Tung, Y.-C.; Wu, W.-C.; Chen, W.-C. Macromol. Rapid Commun. 2006, 27, 1838.

[3] (a) Lin, S. T.; Tung, Y. C.; Chen, W. C. J. Mater. Chem. 2008, 18, 3985. (b) Han, K.; Su, W.; Zhong, M.; Yan, Q.; Luo, Y.; Zhang, Q.; Li, Y. Macromol. Rapid Commun. 2008, 29, 1866. (c) Yang, C.-C.; Tian, Y.; Chen, C.-Y.; Jen, A. K.-Y.; Chen, W.-C. Macromol. Rapid Commun. 2007, 28, 894. (d) Lee, H.; Wu, W.; Oh, J. K.; Mueller, L.; Sherwood, G.; Peteanu, L.; Kowalewski, T.; Matyjaszewski, K. Angew. Chem. Int. Ed. 2007, 46, 2453. (e) Jiang, J.; Tong, X.; Zhao, Y. J. Am. Chem. Soc. 2005, 127, 8290.

[13] A. O. Patil, Y. Ikenoue, F.Wudl, A. J. Heeger, J. Am. Chem. Soc.1987, 109, 1858 – 1859.

[25] Zhang, X.; Xia, J.; Matyjaszewski, K. Macromolecules 1998, 31, 5167. Zeng, F.; Shen, Y.; Zhu, S.; Pelton, R. Macromolecules 2000, 33, 1628. Shen, Y.; Zeng, F.; Zhu, S.; Pelton, R. Macromolecules 2000, 33, 5399.

[9] Zhang, X.; Xia, J.; Matyjaszewski, K. Macromolecules 1998, 31, 5167. Zeng, F.; Shen, Y.; Zhu, S.; Pelton, R. Macromolecules 2000, 33, 1628. Shen, Y.; Zeng, F.; Zhu, S.; Pelton, R. Macromolecules 2000, 33, 5399.