Novel thermosetting diimides containing terminal propargyl groups

A series of new thermosetting diimides containing terminal propargyl groups was synthesized via one-step high-temperature catalytic condensation of dianhydrides of a tetracarboxylic acid with N-Boc-(4-propargyloxy)aniline (APR) in the so-called “active medium”, viz. molten benzoic acid. Structures of the obtained compounds were confirmed by ¹H NMR and IR spectroscopy. The effect of symmetrical and unsymmetrical structures of the middle bis-imide moiety obtained from dianhydrides of isomeric diphenyltetracarboxylic acid on physicochemical characteristics of the diimides was evaluated. A similar comparison of properties was also carried out for a pair of new propargyl-containing diimides synthesized from dianhydrides of symmetric and asymmetric structure: 4,4-biphenylenedioxydiphthalic and 3,4-biphenylenedioxydiphthalic dianhydrides, respectively. Thermal properties of thermosetting oligoimides were estimated using DSC and TMA methods. It was found that their thermal properties and solubility in organic solvents depend significantly on the structure of central bis-imide moiety.