Synthesis and properties of new thermosetting oligoimides containing terminal propargyl groups

A series of new oligoimides based on 4,4- and 3,4-oxydianiline and 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, possessing different average chain lengths, and containing terminal propargyl groups were synthesized according to an efficient single-step high-temperature polycyclocondensation method. Their molecular weight characteristics, solubility in organic solvents, thermal (DSC, TMA, and TGA), and rheological properties were studied. The synthesized oligoimides exhibited a significantly lower exothermic effect upon curing due to their elongated chain as compared to diimides. The oligoimides upon increasing the temperature enter into a viscous fluid state, in which they remain up to the curing onset temperature of 270–320 °C. The symmetry of structure of the diamine moiety (4,4-ODA or 3,4-ODA) and the molecular weight of oligoimides affect the temperature of transition to the viscous fluid state.