以聚(3-己基噻吩)溶液製備一維帶狀銀金屬及成長機制之探究

Abstract

為優化以聚(3-己基噻吩)電紡纖維圖式製作銀金屬－纖維複合物圖式的問題，在本論文裡，我們採用修改靜電紡絲加工程序的策略，以四氫呋喃(THF)液體收集聚(3-己基噻吩)/聚環氧乙烷(P3HT/PEO)混摻電紡纖維以製作有一維帶狀銀金屬沿著電紡纖維延伸的方向包覆成長的銀金屬－纖維複合物，其中導電高分子聚(3-己基噻吩)為電子予體，藉四氫呋喃對聚(3-己基噻吩)的膨潤作用而使銀離子在膨潤的聚(3-己基噻吩)高分子鏈聚集體上還原形成具一維結構的銀金屬。 於溶液裡的聚(3-己基噻吩)為無規則捲曲的構型，高分子鏈之間沒有π-π堆疊(π-π stacking)交互作用；我們將聚(3-己基噻吩)的氯仿溶液滴入含有銀前驅物的四氫呋喃/水共溶劑系統裡探討其溶液態成長具一維結構的銀金屬的成長過程。在這成長過程裡，涉及到：一、以NRTL熱力學模型迴歸關聯計算四氫呋喃－水－氯仿三成份液液相平衡，其結果顯示這系統使用的溶液混合比例藉著液液相分離趨向熱力學穩定。二、由不同溶劑品質的溶劑經擴散而發生的高分子溶液－凝膠轉換，該凝膠轉換為加熱可逆的物理型凝膠化，是因聚(3-己基噻吩)的糾纏所造成。三、在不同時間點開始的銀金屬成長事件，在最適化的時間條件啟動的帶狀銀金屬的長度可達ca. 102 μm。然於銀金屬的結構方面：該帶狀銀金屬結構具有高度的晶體位向排列一致性，其結構主要晶面是為{111}晶面族及<110>的晶面成長方向。在同樣具有高長寬比的一維銀金屬，我們的銀金屬預期會有更好的傳導性質。在我們的銀金屬成長系統裡，不需要額外引入還原劑以及額外的模板，且在常溫、常壓的環境條件下就可以製備得一維帶狀銀金屬－電紡纖維複合物。

Optimizing the problems in the pattern of silver-fiber composites fabricated by a pattern of poly(3-hexylthiophene) (P3HT) electrospun fibers, in this thesis, we adopted a modified electrospinning processing strategy, in which the P3HT/poly(ethylene oxide) (PEO) blending electrospun fibers were collected in a bath of THF. Such the fibers were employed to fabricate the silver-fiber composites, on which there was a part of 1-D belt-like silver grew along with the elongation direction of fibers. P3HT, one conducting polymer, was an electron donor, and what the swelling effect of THF in P3HT let silver ions reduced on the swollen P3HT polymer chain aggregates to generate silver with 1-D structure. P3HT was a random coil in the solution state, where there was no π-π stacking interaction between polymer chains; based on this concept, we introduced a drop of P3HT in chloroform into a THF/water co-solvent system containing silver precursor, discussing the processes that 1-D silver grew via P3HT solution. In such the processes, there were three major topics involved. First, a ternary liquid-liquid phase equilibrium for THF-water-chloroform was estimated by NRTL model regression correlation, and the result demonstrated the molar ratio of mixing solvents in this system became thermodynamically stable via liquid-liquid phase separation. Second, the polymer solution-gel transition (i.e. gelation) happened through molecular diffusion of solvents with different quality, and the gelation causing by the entanglement of P3HT rigid backbone was thermoreversible. Third, there were silver growth events launched at different time, in which the maximal length of belt-like silver was ca. 102 μm when it started on the optimized time. This silver structure had high degree of consistent arrangement, and showed the major crystal plane of {111} and the major growth direction of <110> as well. Our silver was expected to perform more advantageous transporting properties in the case of 1-D silver with high aspect ratio. Last but not least, in our growth system for silver, without any extra reducing agent and other templates, we can fabricate 1-D belt-like silver-electrospun fiber composites under ambient temperature and pressure conditions via addition of silver precursor only.