Preparation and properties of crosslinking polyimides having ethynyl groups on the side

Abstract

3,5-Diamino-4’-ethynylbenzanilide (1) was synthesized from 4-ethynylaniline and 3,5-dinitrobenzoyl chloride. Polyimides (PI-x) having ethynyl groups on the side were prepared from 1, 4,4’-oxydianiline (ODA), and various dianhydrides (x) by the usual two-step procedure that included ring-opening polymerization leading to polyamic acid (PAA-x) and subsequent thermal cyclic dehydration. Since gelation was observed in the polymerization of PAA-c from 3,3’4,4’-benzophenonetetracarboxylic dianhydride (BTDA) (c), the polymerization was performed in the dark. In the dynamic mechanical analysis of PI-x, glass transition temperatures (Tg) were observed at 262–320 °C as tan δ peak temperatures, and the values were higher due to crosslinking of ethynyl groups at 360 °C. Tg of the film prepared from PAA-c solution exposed to a fluorescent lamp was higher than that of a PI-c film prepared in the dark, and photo-crosslinking of ethynyl groups was also observed.