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標題: Exploration on Syntheses of Poly-amide/imide Polymers via Polycarbodiimide Intermediates
作者: 黃偉翔
weihsiang, Huang
關鍵字: isocyanate;異氰酸鹽;carbodiimide;amide;imide;amide-imide;acylurea;碳二醯胺;醯胺;醯亞胺;醯胺─醯亞胺
出版社: 化學工程學系
Our recent research in model reactions of aromatic carbodiimides (CDI) with carboxylic acids [especially with trimellic anhydride (TMA)] has yielded a stepwise selective route for the synthesis of amides (or amide-imides in the case of TMA as a starting acid). When CDI is mixed with carboxylic acids in an ambient temperature, high yields of soluble acylureas can be obtained. The heating of the latter at >130℃ results in formation of amides and isocyanates. In TMA case, isocyanate will further react with amide-anhydride to form amide-imide under the influence of catalyst (PC 41) and give off carbon dioxide simultaneously.
This new sequential methodology has been applied to the synthesis of polyamide-imide polymer (PAI) starting from 4,4'-methylene diphenyl diisocyanate (MDI) and TMA. In the polymer synthesis, MDI was first converted into poly-CDI in the presence of DMPO. Polyacyurea (PACU) was then prepared by mixing P-CDI with TMA. PACU solution was spread on to a substrate and was heated to 220~320℃ to form PAI film. PAI thus formed has shown to have high thermal stability of Tg of >300 ℃and Td of 470℃ with char yield of 40%.
Other syntheses of PAI foams and PI seem also plausible through soluble solution of the respective PACU.

本實驗對於芳香族碳二醯胺(CDI)和芳香族有機酸,特別是和苯偏三甲酸酐(TMA)間的反應有進一步的研究。發現由苯基異氰酸鹽(phenyl isocyanate)所合成的芳香族CDI,與芳香族有機酸酐在常溫下反應生成的『中間產物』acylurea(ACU),具有比一般二元酸、醯胺、醯亞胺等較高的可溶性於有機溶劑之中。另外,ACU也可由熱裂解方式先形成醯胺-酸酐及異氰酸鹽,再利用觸媒(PC 41)的作用下將醯胺-酸酐有效地轉化成醯胺-醯亞胺,並可同步釋出二氧化碳。
本研究之聚醯胺-醯亞胺(PAI)的製備,是採用前所未利用之『分段式』進行法,先將二元異氰酸鹽(4,4’-MDI)以一步驟方式合成高分子碳二醯胺(PCDI),再將PCDI和TMA於低溫下,反應生成Polyacylurea(PACU)中間體,最後以熱處理方式將PACU轉化成PAI。生成PAI最佳的熟成溫度為320℃(約在PAI的Tg之上),時間為4小時,而製得的PAI具有極佳的熱穩定性,其Td為501℃,Tg為308℃,焦碳殘餘量(char yield)為40%。
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