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  • 學位論文

側鏈結構效應對聚芴共軛高分子(PF8及PF2/6)電紡纖維的表面形態、微結構與光物理性質影響的研究

Effect of the side-chain structure of polyfluorenes (PF8 and PF2/6) on the morphology, microstructure and photophysical properties of electrospping fibers

指導教授 : 陳建宏
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摘要


本論文利用光學顯微鏡(OM)、偏光顯微鏡(POM)、掃描式電子顯微鏡(SEM)、UV光吸收光譜(UV-vis)、光激發光光譜(PL)、掃描示差熱卡分析儀(DSC)及X-光繞射儀(XRD)進行側鏈結構效應對poly(9,9-dioctylfluorene) (PF8)和poly[9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl] (PF2/6) 聚芴電紡纖維的形態(morphology)、微結構(microstructure)及光物理性質(photophysical properties)影響的研究: 第二章為探討不同靜電紡絲條件製備PF8電紡纖維對其形態、微結構與光電性質的差異,所獲得的結論如下:在濃度大於12.0wt%,PF8共軛高分子可利用靜電紡絲技術成功製備出均勻型態的PF8電紡纖維,這是因為PF8共軛高分子鏈間的??-?鈰幭|作用力增加PF8分子鏈的共軛鏈長。其纖維直徑約為1.0-2.0?慆,在正交偏振光下所觀測剛紡製好之PF8奈米纖維有明顯的雙折射現象,意味PF8奈米纖維中的PF8分子鏈有延著纖維軸方向的順向排列的異向性結構(雙折射行為)。因此,PF8電紡纖維的紫外光吸收(UV-vis)光譜圖發現PF8共軛高分子奈米纖維的主要吸收峰呈現明顯的紅移(red-shifted)現象。這現象可能是電紡纖維中有較長的共軛結構導致往長波長方向偏移。相對的,在光激發光(PL)光譜圖中發現在PF8電紡纖維擁有較寬波長且呈現明顯的藍移(blue-sifted)現象,這現象歸因於PF8電紡纖維中大量的延著纖維軸順向排列的PF8共軛高分子鏈。並且發現在較高的濃度條件下??-phase聚集結構的含量增加導致意味??-phase聚集結構的光激發光峰強度隨之增加。PF8電紡纖維的WAXD繞射圖呈現PF8電紡纖維得微結構主要為非晶結構。因此在熱分析中在約57 oC有一玻璃轉移溫度及熱應力釋放峰,並且在約80 oC有一明顯且大的熱結晶化峰產生,隨後在約120 oC有一微弱的結晶相轉變峰以及在約145 oC有一PF8結晶的熔融峰。因此利用廣角X光繞射儀解析PF8電紡纖維在升溫過程的微結構的轉變。 另外,第三章為進行不同製條件對PF2/6共軛高分子電紡纖維的型態、微結構、光物理性質及熱性質等分析,本章節之結論如下:PF2/6共軛高分子也可直接利用電紡紡製成直徑約1.0-2.0 ?慆的均一性PF2/6共軛高分子電紡纖維。並且由分析中發現PF2/6電紡纖維中PF2/6共軛高分子鏈也延纖維軸方向排列的非結晶結構,因PF2/6共軛高分子鏈間並無明顯的分子鏈間的片狀聚集結構(??-phase),導致PF2/6電紡纖維的UV光吸收光譜及光激發光行為均明顯朝短波長方向偏移(藍移),因此可激發出較高能量的深藍色發光。因此在UV光吸收光譜圖中PF2/6電紡纖維呈現比一般PF2/6薄膜有些許紅移現象;相對的在PL光激發光光譜圖中PF2/6電紡纖維呈現比一般PF2/6薄膜有明顯的籃移現象,這現象表示PF2/6電紡纖維為高順向性且規則排列分子鏈研纖維軸方向排列所導致。相對的PF2/6薄膜中為含有不規則排列的PF2/6之α-相結晶,因此在DSC及XRD分析中顯示出PF2/6薄膜為含有局部結晶性的材料且其熔融峰溫度為158 oC,並且在冷卻過程中於溫度為99.2 oC有明顯的結晶化溫度。相對的PF2/6電紡纖維因高順向性但快速固化而形成含有順向的繞射峰的非晶結構,因此在DSC中僅在溫度約為147.8oC有一微小的熔融峰(Tm)。由以上結果意味因PF2/6電紡纖維中分子鏈受牽伸力作用之下呈現較高順向性的PF2/6分子鏈延電紡纖維軸方向排列成液晶狀的結構。

並列摘要


In this work, we provided insights into effects of the side-chain structure of polyfluorenes; poly(9,9-dioctylfluorene) (PF8) and poly[9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl] (PF2/6) on the morphology, microstroctore and photophysical properties of electrosppining nanofibers through the optical microscope (OM), polarized optical microscope (POM), scanning electron microscope (SEM), differential scanning calorimeter (DSC), Wide angle X-ray Diffraction (WAXD), UV-vis absorption (UV-vis) and photoluminescence (PL) spectra. In the second chapter, the effect of the prepare condition on the morphology, microstructure and photophysical properties of PF8 electrosppining nanofiber. The conclusion of the charpt as shown in below: In the concentration higher than 12.0wt%, PF8 cnjugated solution can format a uniform and homogenous electrospun fiber with diameter ca. 0.5 – 2.0 ?慆, which presente a clearly green-blue emission profile attributed to more ??-phase domains accompanied with high-extended PF8 polymer chains in the fiber axes. Compared with the drop-casted thin-film, the microstructure of PF8 electrospun fiber shows a red-shifted in the UV-vis, while that presents a blue-sifted in the PL spectra, attributing to the high-extended of PF8 chains in the fiber axes of PF8 electrospping fiber promote a higher energy in the absorption and emission behavior. However, compared with drop-casted thin film, the microstructure of PF8 electrospun fiber presentes the amorphous metastable structure; therefore, more complexly thermal properties of the PF8 electrospun fiber displaies in DSC. In heating trace the thermal behavior of PF8 electrospun fiber shows a stress-relief peak at ca. 57 oC and a cooling crystallization exothermic peak at ca. 80 oC, and then presents a crystallization transition peak at ca. 120 oC followed by a melting endothermic peak at ca. 145 oC. Moreover, these crystallization and crystal structure transition behaviors of PF8 electrospun fiber also provide by the heat-dependence wide angle X-ray diffraction (WAXD) technical. In the third chapter, we study the effects of the prepare condition on the morphology, microstructure and photophysical properties of PF2/6 electrospun fiber, the conclusion of the chapter as shown in below: Herein, PF2/6 conjugated polymer also could prepare a uniform and homogenous morphology with diameter ca. 1.0 – 2.0 ?慆 electrospun fiber. The PF2/6 electrospun fiber presentes a clearly deep-blue emission attributed to a more high-extended PF2/6 polymer chains and small content ??-?? stacking ??-phase domains in the PF2/6 fiber axes. Therefore, PF2/6 electrospun fiber shows a more blue-sifted in the UV-vis and PL spectra, respectively. Moreover, compared with the PF2/6 drop-casted thin film, the photophysical properties of PF2/6 electrospun nanofiber also presents a red-shifted in the UV-vis, while that shows a blue-sifted in the PL spectra, corresponding to the high-extended of PF2/6 chains in the fiber axes of PF2/6 electrospun fiber promote a higher energy in the absorption and emission behavior. On the other hand, the broadness of the UV-vis and PL spectra in PF2/6 electrospun fiber corresponds to the heterogeneous of the fiber dimension and nanoporous on the fiber surface. The XRD result displaies some ordered ??-form crystals in the PF2/6 thin-film, thus it showed a melting endothermic peak at ca. 158 oC. Whereas, the PF2/6 electrospun fiber displaies an amorphous structure; therefore, the thermal behavior of PF2/6 electrospun fiber shows a very small melting endothermic peak at 147.8 oC. These results indicates that PF2/6 polymer chains presente a high-extended PF2/6 polymer chains in the PF2/6 electrospun fiber axes by the drafting force of the electrospping technology.

並列關鍵字

polyfluorenes electrospping fibers PF8 PF2/6

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