| Research Abstract |
Preparation and properties of polyimide gels were clarified for the first time under this project. Polymide gels were prepared by (1) spontaneous gelation of polyamide acids, (2) addition of crosslinking reagent, and (3) chemically crosslinking of polyimide chains. Isocianates are one of the crosslinking reagents, whose chemical structure affects on the gelation reactions.
Volume phase change phenomena of the polyimide gels were observed in Water-NMP mixed solution. The volume change occurs continuously or discontinuously depending on the solvent. The mechanism involves change of hydrogen bonds and dielectricity of the solvents.
Those phenomena were also observed by the fluorescence change during phase transition. Fluorescence efficiency of the polyimide gels was higher than or dinary polyimides. Absorbance of the polyimide gels was smaller than conventional polyimide films, showing that they have small dielectric constants. This properties is one of the great advantage of polyimide gels in applying high speed electronics.
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