Radical copolymerizations of butyl methacrylate and macromonomers prepared by the ring-opening polymerizations of L-lactide and ɛ-caprolactone initiated with hydroxyethyl methacrylate produced comb-shaped polymers grafted with hydroxy-terminated oligolactide and oligocaprolactone (PBML and PBMC). The crosslinking reactions of PBML and PBMC with hexamethylene diisocyanate produced polyurethane networks (PUN-BML/C) with the feed PBML/PBMC weight ratios of 100/0, 75/25, 50/50, 25/75 and 0/100. The formation of polyurethane network structure was confirmed by the analyses of FT-IR spectra and gel fractions. The glass transition and 5% weight loss temperatures (T_g and T_d5) of PUN-BML/C 100/0 and PUN-BML/C 0/100 were much higher than those of PBML and PBMC, respectively. Scanning electron microscopic and dynamic mechanical analyses revealed that the oligolactide and oligocaprolactone segments of PUN-BML/C 75/25, 50/50 and 25/75 conetworks are not fully miscible to each other but compatibilized to some extent. The tensile strength and modulus of PUN-BML/C increased with increasing feed PBML content, and PUN-BML/C 75/25 exhibited the highest elongation at break and tensile toughness.