自組裝膠體晶體及其金屬反蛋白石結構之製備及特性分析

Abstract

本研究以電泳披覆法 (Electrophoretic deposition) 分別製作平板及柱狀自組裝膠體晶體於ITO導電玻璃及碳纖維上。以最佳化之參數所製備之平板膠體晶體具有單一光子能隙 (Photonic band gap) ，其能隙位置會隨著實驗中使用之微球尺寸而改變；而柱狀膠體晶體由於反射面積有限，加上自組裝之微球延柱狀表面呈輻射狀之排列，導致其光子能隙強度減弱，然而，其反射峰之半高寬卻因柱面之特性而增加。另外，柱狀膠體晶體表面由於入射光之散射，因此可觀察到彩虹般的平行線。 本研究接著以定電壓1 V在50 ℃下進行電鍍 (Electrodeposition) ，將鎳填入膠體晶體之孔隙中，製備金屬反蛋白石結構，再以250℃之熱處理去除結構內之聚苯乙烯微球。由於膠體晶體之侷限，金屬反蛋白石結構具有特定的成長方向。另外，隨著熱處理的時間增加，聚苯乙烯可完全被移除，同時結晶性也隨之增強，電阻率隨之下降。在光學分析上，平板鎳之反蛋白石結構具有光子能隙邊界 (Photonic band edge) ，而柱狀結構則具有共振腔之特性。

Planar and cylindrical colloidal crystals were fabricated by electrophoretic deposition with 460 and 660 nm PS microspheres on ITO-glass and carbon fibers, respectively. To improve the quality of the colloidal crystals, variables including microsphere concentration, electrical field, and deposition time were investigated. With the optimized process, the multi-layer colloidal crystals with ordered structure could be obtained within 1 hr. In planar colloidal crystals, we observed an obvious photonic band gap in reflectance spectra. In contrast, a series of iridescent fringes was present in cylindrical colloidal crystals. To fabricate Ni inverse opals, potentiostatic electrodeposition was carried out on the colloidal crystals. With careful control in the plating step, we were able to obtain inverse opals in finite thickness. To remove the PS microspheres, the deposited samples underwent chemical dissolution using ethyl acetate and thermal oxidation at 250 ℃ after the electrodeposition. The heat treatment was able to clean the PS microspheres without structure distortion. Meanwhile, the crystallinity of the Ni inverse opals was improved during the heat treatment.