P3HT及P3HT/PCBM電紡纖維之形態、結構與光物理性質的研究

The morphology, microstructure and photophysical properties of P3HT and P3HT/PCBM electrospun fibers

陳勝南(Sheng-Nan Chen)

指導教授 ： 陳建宏

崑山科技大學/工程學院/材料工程研究所/碩士(2011年)

https://doi.org/10.6828/KSU.2011.00089

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)、掃描式熱卡分析儀(DSC) 及X-光繞射儀(XRD)進行一系列聚噻吩(Poly(3-hexylthiophene) (P3HT))及P3HT/奈米碳球(PCBM)混摻奈米纖維的形態(morphology)、微結構(microstructure)及光物理性質(photophysical properties)影響的研究，本研究結果獲得以下的結論：
第二章，由OM及 SEM結果顯示P3HT電紡奈米纖維在較高濃度及較強的靜電壓下可形成較均勻的纖維外觀形態且降低纖維直徑至約200奈米。相對的由POM觀測中得知P3HT電紡奈米纖維呈現出一個清晰的雙折射現象歸因於靜電牽伸力誘導P3HT高分子鏈沿著纖維軸方向排列所產生的高順向性結構。因此在紫外光(UV-vis)及光激發光(PL)光譜圖結果表明P3HT奈米纖維的光激發光和吸收效率的光物理性質是明顯的優於一般滴鑄膜，由於P3HT奈米纖維的高表面積的能量吸收現象及P3HT高分子鏈沿著奈米纖維軸對齊排列呈現的高順向性有著更顯著的能量轉移效應。WAXD數據顯示P3HT滴鑄膜呈現出P3HT之Type I結晶的(100)、(200)、(300)及(020)繞射峰。相對的，P3HT電紡纖維的WAXD數據顯示明顯的Type I結晶的(100)、(200)、(300)及(020)繞射峰，相對的在2?嶈軉?21.28o之呈現出一額外的Type II結晶的繞射峰。這結果說明P3HT電紡纖維外部之分子鏈因靜電場的牽伸導致P3HT電紡纖維中有致P3HT分子鏈延纖維軸方向排列的Type II結晶的繞射峰及一般完整的Type I結晶結構。並且WAXD顯示P3HT電紡奈米纖維中Type I結晶繞射峰的角度比P3HT滴鑄膜低表示P3HT電紡奈米纖維中Type I結晶中晶面間距(d-space)較寬，表示P3HT電紡纖維的結晶結構較一般的P3HT滴鑄膜有較複雜的結晶結構及較不完整的結晶結構。因此在DSC圖譜中P3HT奈米纖維呈現熔融溫度較低的雙重熔融峰(高順向性的Type II及一般規則堆積且較不完整的Type I結晶)。另一方面，在DSC冷卻過程P3HT奈米纖維的結晶化速率大於P3HT滴鑄膜應該為奈米纖維表層的順向性分子鏈將作為如晶核功能而加速P3HT的結晶化。
在第三章，利用固定重量濃度為15.0 wt%之不同混摻比P3HT/PCBM混合溶液製備一般滴鑄膜及電紡奈米纖維以探討PCBM含量對P3HT/PCBM電紡奈米纖維的外觀形態、微結構及光物理性質影響研究。由OM及SEM數據顯示隨PCBM含量的增加，不同混摻比之P3HT/PCBM電紡奈米纖維的外觀形貌將由一均勻性的纖維結構轉變成含有大量紡錘狀及液滴狀的纖維結構，這現象意味隨PCBM含量的增加，P3HT/PCBM混摻體系中的P3HT共軛高分子的含量及P3HT分子間的糾結程度下降，因此靜電場作用下無法紡製成均勻的纖維結構。在POM觀測得知不同混摻比之P3HT/PCBM電紡奈米纖維中P3HT高分子鏈沿著纖維軸方向排列所產生的順向性結構隨PCBM含量的增加逐漸降低。在UV-vis光譜圖結果表明隨PCBM含量的增加，P3HT/PCBM電紡奈米纖維的吸收效率明顯增加。而歸一化UV-vis光譜圖中發現隨PCBM含量的增加不同混摻比之P3HT/PCBM電紡奈米纖維在波長為200-300、350及650nm以上的範圍有明顯的UV-vis光吸收增加現象歸因於奈米化的PCBM奈米球結構的吸收特性。另一方面，由WAXD數據顯示P3HT/PCBM電紡纖維及薄膜中呈現出明顯之P3HT的Type I結晶的繞射峰之外還有P3HT的Type II結晶的繞射峰。相對的，在較低含量之PCBM條件下，P3HT/PCBM電紡奈米纖維在2?嶈軉?17o~21 o呈現一均勻分散的非晶散射峰；相對的，在較高含量之PCBM條件下，P3HT/PCBM電紡纖維及薄膜於2?嶈軉?3.48o、7.32 o、20.06o、21.86o及23.1o也呈現出額外的PCBM結晶繞射峰，意味不同混摻比之P3HT/PCBM共軛高分子溶液在電紡過程中產生明顯的液液相分離現象，並且P3HT及PCBM分子在相分離區中各自結晶。最後在DSC分析圖得知不同混摻比P3HT/PCBM共軛高分子奈米纖維均顯示一個清楚較寬的熔融峰(由Type I及Type II合併結晶的熔融)，此熔融溫度隨PCBM含量之增加由230.2°C（較完整結晶的熔融）下降至208.4°C（更不完善的結晶的熔融），這現象意味P3HT/PCBM共軛高分子奈米纖維中結晶結構的完整性或微結晶尺寸隨PCBM含量的增加而明顯的下降的趨勢。

關鍵字

電紡 ； 奈米纖維 ； 聚噻吩 ； 共軛高分子

並列摘要

In this work, we provided insights into the morphology, microstroctore and photophysical properties of Poly(3-hexylthiophene) (P3HT) and blended P3HT with different contents of phenyl-C61-butyric acid methyl ester (PCBM) (P3HT/PCBM) fibers 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, OM and SEM showed that a uniformly morphology with diameter ac. 200 nm electrospun P3HT fibers prepared by higher concentration of P3HT and higher voltage power supply. The result of POM presented that a cleanly birefringence image of electrospun P3HT fibers attributed high orientation P3HT polymer chain were packed and aligned along the fiber axes. Therefore, results of photophysical properties; such as UV-vis and PL spectra, indicated that the absorption efficiency and photoluminescence of P3HT fibers larger remarkably and smaller seriously, respectively, than that of P3HT thin film and semi-dilute solution meant that a significant energy transfer was presented due to the high orientation P3HT polymer chain were packed and aligned along the fiber axes within the nanofibers. Our results demonstrated that the morphology and photophysical properties of electrospun P3HT fibers have tunable by directly electrospinning technique. However, the result of WAXD indicated that the microstructure of P3HT electrospun fibers show the (100)、(200)、(300) and (020) diffraction planes of P3HT Type I crystalline and a diffraction peak at 21.28o for P3HT Type II crystalline. It meant that the microstructure of P3HT electrospun fibers was conbined major part amorphous structure of Type I and minor part Type II crystals in fibers, Finally, the diffraction peaks of P3HT nanofibers shifted to lower diffraction angle than that of P3HT thin film attributes the d-space between thiophene rings in Type I crystal within the P3HT fibers is larger than that within P3HT thin films. Therefore, the thermal behavior of P3HT electrospun fiber showed a lower nelting temperature but multi-melting endothermic peaks at Tm-II = 218 °C, Tm-I = 225 °C, respectively, comparaed with higher melting temperature and single endothermic peak of P3HT thin-film.
In the third chapter, we provided insights into effects of the PCBM content on the morphology, microstroctore and photophysical properties of P3HT/PCBM fibers. However, the OM and SEM showed that the morphology of electrospun P3HT fibers from a uniformly to spindle-like and drops-shape fibers as PCBM content was increased. This maybe due to decreases in the content of P3HT and entanglement between P3HT chains in the P3HT/PCBM solution. The result of POM also presented that reduced in the birefringence of electrospun P3HT fibers with increasing PCBM content. The result of UV-vis spectrum indicated that the absorption efficiency of P3HT/PCBM fibers rised remarkably as PCBM increased. Moreover, in the normalized UV-vis spectrum indicated that the increase in absorption intensities at wavelength c.a. 200-300、350 and 650nm corresponded to the absorption efficiency of PCBM in P3HT/PCBM nanocomposity. Finally, the DSC profile indicated that the melting peck from 230.2°C (perfect crystalline) to 208.4°C (imperfect crystalline) means that the perfecticity and size of P3HT crystal was decreased with increasing PCBM. Therefore, the WAXD profile indicated that the microstructure of P3HT electrospun fibers show the (100)、(200)、(300) and (020) diffraction planes of P3HT Type I crystalline and a diffraction peak of P3HT Type II crystalline. The WAXD profile showed a borad diffraction peaks at 2?? ca. 17o~21 o for PCBM amorphous scattering at lower PCBM content; whereas the WAXD profile presented some diffraction peaks at ca. 3.48o、7.32 o、20.06o、21.86o and 23.1o attribute to the PCBM crystalline. The intensity of the diffraction peaks of PCBM crystalline in P3HT/PCBM fibers lower than that in P3HT/PCBM thin-film meaned that the aggregate or assemble of PCBM molecules in P3HT/PCBM thin-film were larger than that in P3HT/PCBM fibers due to phase-separation driving force during electorspping process.

並列關鍵字

Electrospinning ； Nanofibers ； P3HT ； conjugated polymers

參考文獻

[16]王盈淇.溫度效應對電紡絲製備高分子纖維之影響,成功大學,民國 95 年。

[15]黃怡慧.以電紡絲製備聚羥基丁酸酯,成功大學,民國 93 年。

[14]林健樺.以電紡絲製備聚苯乙烯纖維膜,成功大學,民國 92 年。

[73] Wu W. C., Liu C. L., Chen W. C. Polymer 2006, 47, 527.

[98]Loscertales I. G., Barrero A., Guerrero I., Cortijo R., Marquez M., GaoÁaÂn-Calvo A. M. J. Am. Chem. Soc. 2004, 126, 5376.