Several segmented polyurethanes have been synthesized, based on a variety of hydroxyl-terminated polybutadienes (HTPB) , two of which included a free radically polymerized, branched polybutadiene with an average functionality of 2.1, and a hydrogenated derivative. The third was an anionically polymerized, high vinyl content polybutadiene with an average functionality of 1.9. Polyurethanes were prepared in bulk, without added catalyst, by a two-step process, where first the HTPB was endcapped with an excess of 2,4-toluenediisocyanate followed by chain extension by 1 , 4-butanediol . Series of samples of varying hard segment (urethane) content were prepared by this method.