利用超臨界二氧化碳製備核殼型導電性材料

Abstract

本研究以超臨界二氧化碳為媒介進行導電性核殼(Core-Shell)材料的製備，並且探討以不同的苯磺酸和操作條件在超臨界二氧化碳環境中對於材料導電度的影響。 聚乙烯二氧基噻吩(poly(3,4-ethylenedioxythiophene)，PEDOT)具有高導電率、高透光性以及良好的環境穩定性等特點，目前被廣泛的應用於發光二極體、太陽能電池、超級電容器、電致發光層及選擇性穿透膜等的理想材料。二氧化矽的加入已被證明可以增加材料的耐熱性及機械性能，本研究即進行有機(PEDOT)/無機(SiO2)奈米混成實驗。 本研究探討PEDOT在奈米級二氧化矽表面上進行包覆聚合反應實驗。技術方面可以藉由超臨界二氧化碳技術避免掉化學溶劑的使用，以及透過調整反應時間、壓力即可控制包覆量，並取得最佳的參數條件，反應後的產品進行FTIR及TGA的鑑定PEDOT包覆於Silica表面上的情形，透過UV-vis及四點探測儀分析產物的電學性質，最後透過TEM來觀察不同反應條件下，對於產物結構的影響。結果顯示在溫度為40℃，壓力在280bar，反應時間48小時，質子酸(Decylbenzene sulfonic acid, DBSA)摻合度(DBSA/EDOT)莫耳比為0.2的操作條件下，可以得到最大包覆量為62.69 wt.％，在此條件下的導電度也是最好的，可以達到6.7×10-2 S/cm。利用TEM的觀察中，可以發現材料出現了核殼型(Core-Shell)結構，證明在超臨界二氧化碳環境下能夠進行有機(PEDOT)/無機(SiO2)複合材料的製備。

The conducting core-shell materials are formed using supercritical carbon dioxide as the solvent in this study. The effect of various sulfonic acids and operating conditions on the conductivity of the doping process are discussed. Poly(3,4-ethylenedioxythiophene) (PEDOT) has high conductivity, relatively high transparency and long-term stability. The materials are widely applied in light-emitting diode, solar cell, super capacitor and ion-selective organic transistor. The properties of nanocomposites can be altered by coating the particles with an outer shell that influences the final electrical, thermal and mechanical properties. The synthesis of organic (PEDOT) and inorganic (SiO2) nanocomposites are investigated in this study by applying the supercritical fluid technology. Unlike the conventional process with organic solvent, supercritical carbon dioxide was used as the solvent in this study to coat PEDOT onto the surface of nanosilica particles. The coating process was operated at different pressures, dopant concentrations and doping times. The optimal reaction condition are at 40℃, 280bar, reaction time of 48 hours and the molar ratio of 0.2 (DBSA/EDOT). The product is characterized by FTIR and TGA. The maximum coating percentage is 62.69 wt.％ under the optimal operation condition. The electrical property was analyzed by UV-vis and Four-Point Probe. The maximum conductivity is 6.7×10-2 S/cm. Core-Shell structure of the product was confirmed through the TEM image.