Solid-phase Polycondensation Reaction of Bisphenylurethane and Diamino Dicarboxylic Acid

Abstract

Polyquinazolinediones containing benzimidazole units were prepared by the solid phase polycondensation of O-phenylurethanes with diamino dicarboxylic acids. The solid phase reaction was investigated by TGA and DSC. The quinazolinedione formation involved the addition of amino group to the isocyanate group, formed by the thermal decomposition of phenylurethane, and the subsequent cyclodehydration of formed urea with acid. The polymerization proceeded in two stages, as reported previously in the reaction of bisphenylurethane with diamine. The intramolecular cyclodehydration was suggested to depend uppri the -easiness of mobility of the main chain of the polymer when compared it with that if model reaction., These polymers were thermally stable and partially soluble in organic sclvents. The T, of these polymers was estimated by DSC.