"2,2'-雙取代聯苯聚醯亞胺的合成及其碳材製備"

Abstract

本篇論文利用聯苯為主體，在其2,2'-位置引入不同之取代基，成功合成出三個二胺單體，再與市售二酸酐反應，合成出四種聚醯亞胺。在二胺單體分子設計中，利用剪刀狀構型破壞聯苯的共軛結構，可由X射線的單晶繞射圖證明。因此，所合成出的聚醯亞胺高分子為非共平面的結構，避免分子間的堆疊，可由熱重分析儀與熱示差掃描卡計得知其具有良好之熱穩定性，並且在800 ℃下其碳殘留率都還有50 %以上。利用所合成出的聚醯亞胺高分子在高溫下具有高碳化殘留率，且因其含有耐高溫之多苯環結構，導致其在高溫熱裂解時，可進行分子間或分子內的重排堆疊，形成部分石墨化的結構，其石墨化程度都在30 %以上，可由拉曼光譜和X射線光電子能譜證明之。 為了使碳化的殘留率更高，我們加入銅化合物，藉由銅的催化效應及能促使多個C-C鍵環化形成像苯環之環狀結構，而不至形成小分子氣化，因此可增加碳殘留率並能提高石墨化的比例。

In this thesis, 2,2'-disubstitued biphenyl derivatives of polyimides were successfully prepared. These compounds possess scissor-like conformations which were evidenced by using the spectroscopic, as well as by X-ray crystallography. The presence of the ample conformational variations influences their physical properties and thermal stability: (1) the scissor-like structures would breakdown the intramolecular π-conjugation of the molecule, (2) The non-coplanar structure would also hamper the intermolecular stacking, prohibiting the compounds from crystallization and therefore increasing the thermal stability of their amorphous film structure. Showing through the thermogravimetric analyzer and thermal differential scanning calorimeter were observed that the materials have good thermal stability. They have more than 50 % of carbon residue at 800 °C. Because the high temperature resistant synthetic materials have more aromatic structure, pyrolysis part of the molecule will be re-arranged in parallel to the aromatic stack. Therefore, we use Raman spectroscopy and X-ray photoelectron spectroscopy to confirm that the materials are formed partly graphite structure and the degrees of graphitization are in more than 30 %. To get higher residual ratio of carbonization, we added copper compounds to these polymers. By the catalytic effect of copper, it could induce multiple C-C bond cyclization to form the ring structure like aromatic rings. Therefore, we can increase the carbon residue ratio and the proportion of graphite.