an energetic copolyurethane thermoplastic elastomer is prepared by polymerizing a dihydroxyl terminated telechelic energetic polymer having a functionality of two or less with a diisocyanate at a nco / oh ratio of about 0 . 7 to 1 . 2 . the resulting copolymer is easy to incorporate in gun propellant or explosive formulations and is recyclable . these energetic copolyurethane thermoplastic elastomers were obtained mainly by macropolymerization of gap prepolymers with 4 , 4 ′- methylenebis - phenyl isocyanate . in these syntheses , gaps having molecular weights of 500 , 1000 and 2000 were used as macromonomers and polymerized with mdi to yield three different copolyurethane thermoplastic elastomers . this process may be applied to any dihydroxyl terminated energetic prepolymers . the hard segments of the etpe are obtained by the formation of hydrogen bonds between the urethane groups .