Synthesis of telechelic macromonomers was performed in two steps based on our previous work and the reaction scheme is presented in Figure Error! Reference source not found.. In the first step, 50 mL of EtOAc in a 250 mL round-bottom flask was degassed with three argon/vacuum cycles. Then, the flask was placed in an ice bath and different amounts of catalyst (0.1, 0.25, 0.50, and 1 mol% calculated with respect to Priplast OH groups) and 13 mL of IPDI were added. After that, 50 g of Priplast (P1838), dissolved in 50 ml of EtOAc, was added dropwise, the flask was immersed into an oil bath, and the reaction was carried out at 70 °C in argon atmosphere. The second step was started when the ratio of A2262/A1526 of decaying N=C=O groups and forming urethane bonds (bending N-H vibrations), as calculated from FT-IR spectra, reached approx. 5. Based on NCO titration, this value corresponds to approx. 50% of reacted groups. For the case of the synthesis with use of the 0.1 mol% of catalyst, the ratio stabilized at approx. 10, therefore the second step was started with this higher ratio. Then, 6 mg of PTZ (inhibitor), a second dose of catalyst (the same amount as in the first step), and 13.2 mL of HEMA were added to the reaction mixture. The reaction was considered finished when all of the isocyanate groups were converted, as determined using FT-IR (absence of the band at 2262 cm -1 ). The flask was then removed from the oil bath and allowed to cool to room temperature.