PCL-segmented multiallyl-functionalized poly (ester urethane) prepolymers (PEUs) were prepared in a two-step process. First, hydroxyl-terminated PCL and glycerol simultaneously reacted with an excess of a diisocyanate, the obtained isocyanate functionalized prepolymers then reacts with allyl amine. PEUs structure choice mainly focused on two aspects: the PCL segments concentration and the allyl functionality that, respectively, affects the biodegradability and the density of the issued networks. The concentrations of the different reactants were fixed, taking into account the desired mean structure and also to prevent crosslinking during the synthesis of the prepolymers. FTIR was principally used to monitor the synthesis of allyl functionalized PEUs. The carbonyl absorption of PCL, initially located at 1720 cm−1, reaction of the PCL and shifted toward 1730 cm−1, due to a decrease in crystallinity as confirmed by DSC. The structure of allyl-functionalized PCL-segmented PEU analyzed by 1H NMR, double bond content was between 0.2 and 1.2 mmol g−1. Networks were obtained by UV-initiated radical copolymerization of allyl-functionalized PEUs and HEMA. The effects of PCL concentration and molar mass on their thermomechanical and thermal properties were analyzed. Particular damping properties were obtained. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41295.