含碳六十之新型態高分子複合體的合成分析與其光電性質之研究

Studies on Novel C60-anchored Polymers and Their Optoelectronic Properties

朱智謙(Chih-Chien Chu)

指導教授 ： 何東英

共同指導教授 ： 王立義(Leeyih Wang)

國立臺灣大學/理學院/化學研究所/博士(2005年)

https://doi.org/10.6342/NTU.2005.00065

摘要

在本篇論文中，我們首先成功的合成出定義明確的新型態的多重臂鏈含碳六十之高分子。我們製備出核心為malonate ester、尾端為多重活性溴基的起始劑，接著再利用原子轉移自由基聚合法合成出分子量可受控制且分佈窄的的二、四、八臂鏈poly(tert-butyl acrylate)（PtBA）高分子。由於高分子核心部分之malonate ester，此不同臂鏈數目的高分子可以藉由Bingel三環加成反應與碳六十進行反應而得到新型態多重臂鏈含碳六十之高分子。由GPC、NMR、UV-vis所得到的高分子分子量分析結果顯示它們屬於單取代的碳六十衍生物。而在1H-NMR的分析中，含碳六十之高分子結構中靠近碳六十的氫原子訊號因為碳六十分子的拉電子效應產生明顯的低場位移與多重分裂等現象，此結果顯示出碳六十已經成功的鍵結在此不同臂鏈數目的高分子上。而相較於碳六十分子，此新型態高分子在UV-vis吸收光譜中的藍位移現象，更可以被進一步判斷出高分子在碳六十表面上的鍵結方式為σ-homoaromatic（又稱為6-6-ring-bridged）的模式。接著在TFA酸性水解條件之下，我們成功的將多重臂鏈含碳六十之PtBA高分子臂鏈上的tert-butyl保護基團完全除去而得到水溶性多重臂鏈含碳六十之poly(acrylic acid)（PAA）高分子。而我們在GPC-MALLS-RI的分析中發現水溶性的二及四臂鏈含碳六十PAA高分子有明顯的兩性分子聚集行為，而八臂鏈高分子則因為對於核心疏水的碳六十分子的包覆較為完整，因此在水中並不會產生聚集的現象。而由靜態光散射法所計算出來二臂鏈高分子的聚集數目、Rg值，與動態光散射法所計算而得的Rh值都顯示出此高分子聚集體是屬於單一核殼型微胞，並非單一臂鏈含碳六十之高分子常見的二次聚集體—large compound micelle（LCM）。而我們也由AFM的分析中，明顯的觀察到二臂鏈高分子在水中所形成單一核殼型微胞粒子，其粒徑分佈約在10~60 nm之間，此數值與光散射法所計算出來的粒徑大小相當吻合。最後我們也將水溶性二臂鏈及八臂鏈含碳六十之PAA高分子與帶有正電荷的紫質衍生物—TMPyP，藉由靜電作用力相互吸附後得到具備”給體—受體”（donor-acceptor）電荷轉移能力（charge transfer）的高分子複合體。由於二臂鏈高分子系統在水中容易形成聚集體的緣故，吸附在外殼PAA層的TMPyP可以與核心的碳六十分子簇同時進行分子內與分子間的電子轉移，造成複合體中紫質共軛環的Q band螢光放射的quenching效率可以達到80%以上，而此數值為在水中以單一分子形式存在的八臂鏈高分子與TMPyP複合體的兩倍。

關鍵字

碳六十 ； 高分子 ； 紫質 ； 原子轉移自由基聚合 ； 光激發電子轉移

並列摘要

Synthesis of novel C60-anchored telechelic and star-shaped polymers has been demonstrated. First, multi-armed poly(tert-butyl acrylate) (PtBA) bearing a malonate ester core and well-controlled molecular weight was synthesized through atom transfer radical polymerization (ATRP). Based on ‘arm-first’ strategy, the highly effective Bingel reaction between C60 and the polymers was then introduced to yield the novel macromolecules anchored to a C60 core. The GPC profiles obtained by UV and RI dual detectors indicated that C60 had been covalently bonded to the polymers. The molecular weights of the C60-bonded telechelic and star-shaped polymers ((PtBA)n-C60, n = 2, 4, 8) were similar to that of the homopolymers (PtBA), and these results strongly suggested that the C60-bonded polymers were monosubstituents. 1H-NMR analysis demonstrated the clear down-field-shift of the benzylic protons in the relating C60-based polymeric structures due to the electron-withdrawing properties of C60 moiety. Thus, the results reinforced the conclusion that C60 had been covalently bonded to the polymers. Furthermore, UV-vis studies showed an apparent blue shift and a sharp band atλmax = 426 nm for C60-bonded telechelic and star-shaped polymers in comparison with C60 molecule. The absorption phenomenon seems to be highly characteristic for ‘closed’ 6-6-ring-bridged methanofullerene derivatives. Moreover, the C60 contents in these polymers can be determined by facile quantitative calculation based on Beer’s law from the absorbance atλmax = 326 nm. The results were consistent with the theoretical values calculated based on the assumption that C60-derived polymers was a monoadduct. Subsequent acidic hydrolysis of multi-armed C60-anchored PtBA successfully led to corresponding water-soluble multi-armed C60-anchored poly(acrylic acid) (PAA). The aggregation behavior for the novel water-soluble C60-anchored polymers in aqueous solution was carefully examined using GPC-MALLS-RI technique, dynamic light scattering (DLS), and atomic force microscopy (AFM). Based on preliminary calculation of the average aggregation numbers, Rg and Rh values for these polymers, two-armed C60-anchored PAA revealed apparent primary intermolecular association which corresponds to the individual micelle-like aggregates, but eight-armed C60-anchored PAA still remained unimers in aqueous solution since hydrophobic/hydrophilic balance was easily achieved through intramolecular association. Moreover, AFM images also showed that the dimensions of the micelle-like aggregates comprising of two-armed C60-anchored PAA range from 10 to 60 nm. Finally, donor-acceptor nanoensembles were prepared via electrostatic interactions of multi-armed C60-anchored PAA and water-soluble porphyrin derivative (TMPyP). The fluorescence quenching efficiency monitored by PL studies for the two-armed C60-anchored PAA/TMPyP nanoensembles was a 2-fold increase than that for the eight-armed C60-anchored PAA/TMPyP nanoensembles. Such enhancement of the fluorescence quenching, observed for the two-armed C60-anchored PAA/TMPyP nanoensembles, implied that the electron transfer takes place intramolecularly as well as intermolecularly due to the unique micelle-like aggregation behavior of two-armed C60-anchored PAA.

並列關鍵字

fullerene ； polymer ； porphyrin ； ATRP ； PET

參考文獻

3. [a] Hirsch, A. Fullerenes and Related Structures; Springer: Hidelberg, 1999. [b] Anantharaj, V.; Bhonsle, J.; Canteenwala, T.; Chiang, L. Y. J. Chem. Soc., Perkin Trans. 1999, 31. [c] Wudl, F. J. Mater. Chem. 2002, 12, 1959. [d] Canteenwala, T.; Padmawar, P. A.; Chiang, L. Y. J. Am. Chem. Soc. 2005, 127, 26.

5. Ederle, Y.; Mathis, C. Macromolecules 1997, 30, 4262.

9. Yang, J.; Li, L.; Wang, C. Macromolecules 2003, 36, 6060.

10. Chiang, L. Y.; Wang, L. Y.; Kuo, C. S. Macromolecules 1995, 28, 7574.

11. Anantharaj, V.; Wang, L. Y.; Canteenwala, T.; Chiang, L. Y. J. Chem. Soc., Perkin Trans. 1 1999, 3357.