The expected depletion of oil resources and a greater awareness for the environmental impact of plastic products have created a strong interest toward energetic polymers that are not only biodegradable but also obtainable from renewable resources. In this work, a copoly(ester/ether) was synthesized from polyepichlorohydrin and sebacoyl chloride using pyridine as a Lewis-base catalyst. The chlorinated polymer was azidified with NaN3 in dimethyl sulfoxide solutions. The success of the reaction was confirmed by H-1-NMR, C-13-NMR, and Fourier-transform infrared spectroscopy. Two types of polyurethane networks were synthesized from the nonenergetic and the energetic copolymers, adding polycaprolactone triol and using L-lysine diisocyanate as a nontoxic curing agent. The two resulting polyurethanes were soft thermoset elastomers. The polyurethanes were chemically and mechanically characterized, and their biodegradability was evaluated in compost at 55 degrees C. The nonenergetic and the energetic polyurethanes showed a glass-transition temperature of -14 degrees C, and -23 degrees C, respectively. The weight loss of the polyurethanes during the composting experiments was monitored. It increased almost linearly with time for both materials. After 20 days, the nonenergetic samples lost about 50% of their mass because of the biodegradation mechanism. Instead, the energetic elastomers lost only about 25% of their initial mass after 25 days. The experimental results revealed that the azide pendant group in the soft segment (the polyether segments) is the main factor that controls the physical, mechanical, and degradation properties of these polyurethane networks. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 3645-3657, 2011