Preparation and characterization of some new diaminobisimides

Abstract

A series of stable diaminobisimides (DABIs) has been prepared as alternatives to simple aromatic diamines for use in the preparation of condensation polymers. These DABIs were prepared by reacting two moles of an aromatic diamine with one mole of a dianhydride under conditions that minimize side reactions and the formation of oligomers. In many cases, the pure DABI consisting of two moles of the diamine and one mole of the dianhydride (i.e. the 2:1 product) can be obtained free of oligomers (i.e. the 3:2, 4:3 etc products). The studies have shown that the major factor determining the yield and purity of a DABI is the extent of conjugation between the two amino groups in the starting diamine: to a lesser extent steric effects in the diamines also influence the product composition. The reaction conditions necessary to produce these new DABIs are described together with extensive characterization of these materials by FTIR, ¹H and ¹³C NMR and gel permeation chromatography. The results indicate that pure DABIs are more manageable materials than the impure. insoluble materials previously described in the literature and can be used successfully to produce useful high-temperature stable polymers.