High performance crosslinked polyimide based on main-chain type polybenzoxazine

Abstract

A main-chain type polybenzoxazine with amic acid and benzoxazine groups as repeating units in the main chain, termed as poly(benzoxazine amic acid) (poly(BZaa)), has been synthesized. It has been prepared by a polycondensation reaction of primary amine-bifunctional benzoxazine with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride using dimethylacetamide as the solvent. Poly(BZaa) can undergo a crosslinking reaction to form a crosslinked polyimide (cPI) at 300 °C. Additionally, a model reaction is designed from the reaction of 3-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-amine with phthalic anhydride. The structures of the model compound are confirmed by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopies. Differential scanning calorimetry (DSC) and FTIR are also used to study the crosslinking behavior of both the model compound and polymers. The thermal properties of the crosslinked polymers are also studied by thermogravimetric analysis (TGA).