Preparation and Properties of Polyamides by Ring-opening Polyaddition Reaction of N, N'-Bis(ethoxycarbonyl)pyromellitimide with Aromatic Diamines

Abstract

Polyamides were prepared by the ring-opening polyaddition reaction of N, N'-bis(ethoxycarbonyl)pyromellitimide with bis(4-aininophenyl) ether (ODA) and other aromatic diamines in N-methyl-2-pyrrolidone (NMP). The preparation of high molecular weight polymer required high monomer concentration and a longer reaction time such as over 5 days at room temperature. When the reaction temperature was raised to 70° C, gelation was occurred due to the partial imidization of the resulting polyamide, along with the increase of the rate of polymerization. The polyamide having the highest viscosity was obtained from ODA among the aromatic diamines. Tetrahydrofuran was not satisfactory as reaction medium, because the polymer was precipitated from the reaction mixture during the polymerization. The polyamide solution in NMP showed good hydrolytic stability against the contact of water. DTA curve of the polyamide exhibited an endothermic peak at 160° C, which is attributable to elimination of urethane during polyimide formation. The behavior was also supported by TGA.