The main aim of this study was the preparation of modified polyureas with improved thermal stability and solubility. Accordingly, a series of aromatic/aliphatic pyridine-based polyureas was synthesized from the reaction of a novel diamine (DA) with different diisocyanates, including 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, 1,5-naphthalene diisocyanate, and isophorone diisocyanate, by a solution polymerization route. The DA monomer was prepared via a two-step reaction. The nucleophilic substitution reaction of oxydianiline with 6-chloronicotinoylchloride led to the preparation of a diamide dichloro compound, and the subsequent reaction of this compound with 4-aminophenol resulted in the preparation of the DA. After polymerization, the structural characterization and physical properties of the polymers were examined. The resulting polymers were soluble in common polar aprotic solvents, and they showed improved thermal stabilities in comparison with common polyureas. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012