This article studies the development of a series of heterocyclic polyurethanes (PUs) with various pyridazine content and different crosslinker structure in their main chains. All of the isocyanate-terminated PU prepolymers were prepared from poly(tetramethylene oxide) glycol of molecular weight 1400 (Terathane 1400) and 1,6-hexamethylene diisocyanate. The properties of the obtained linear and crosslinked pyridazine-based PU were compared with the properties of common PUs obtained by chain extension with 1,4-butanediol. All the obtained PUs were characterized through spectral and thermal behavior. The pyridazine-based PU showed improved thermal stability with 10% weight loss at temperatures above 370400 degrees C. With the increase of pyridazine content the values of Young's modulus are higher and the strain at break decreases. Increasing pyridazine content leads to increased films surface hydrophilicity. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013