| Summary: | 碩士 === 國立中興大學 === 化學工程學系 === 91 === This study concerns the thermally induced cycloaddition reactions of ketenes with Methylene-(diphenylene isocyanates), MDI. Through the optimization of reaction condition and ketene candidates, we have found high yield syntheses of mono- and bis-azetidine-2,4-diones.
Aromatic azetidine-2,4-diones have been found to have several good characteristics to be used for as polymer intermediates. Firstly, they are thermally stable even heated to 220 ℃ for short period of time without sign of decomposition. Secondly, they react rapidly and almost quantitatively with aliphatic primary amines into malonamide derivatives at ambient temperature. Lastly, the reactions of azetidine- 2,4-diones with alcohols, secondary amines, and aniline are far less slower than those of aliphatic amines, such that the latter tend to be dominant when mixture of the above were co-existing as the co-reactants.
We also have investigated the polymerization of aliphatic amines with bis-azetindine-2,4-diones and have prepared several high molecular weight malonamides. Polymerization could be conveniently carried out in the melt by mixing to the bis-azetidine-2,4-diones with primary amines in absence of solvent. The thermal analysis of the polymer showed that Tgs are 90~135℃ and Tds are generally greater than 330 ℃. The speed of the ring-opening reaction seems to be slightly slower than those of polyurethane preparation, but thermal stability seems superior. Further research should be able to utilize bis-azetidine-2,4- diones for one-shot syntheses of polyamides and polyamide elastomers.
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