An in situ characterization method using liquid Nuclear Magnetic Resonance (NMR) spectroscopy has been developed to aid the preparation of highly reactive non-isocyanate polyurethanes (NIPUs) from cyclic carbonate aminolysis. Using this methodology, the aminolysis kinetics and the final polymer structure of a model NIPU obtained by reaction of a 5-membered bis-cyclic carbonate (5CC) and 1,4-diaminobutane have been fully investigated, as a function of the type and concentration of the aminolysis catalyst, and the reaction temperature. Several catalysts already reported in NIPUs syntheses, including 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), have been compared. The kinetics of the 5CC hydrolysis side reaction was also studied. With an activation energy of 29.7 kJ mol -1 , TBD was clearly the most efficient catalyst used, allowing 5CC conversion ratio of up to 100 % using a concentration of 0.35 eq 5CC . However, under these experiment conditions, TBD concentration also showed to have a non-negligible influence on the hydrolysis rate, representing between 6 and 14 % of the initial 5CC concentrations, at 353 K. Neither the catalyst or the temperature seemed to affect the polymer structure, with secondary hydroxyl-containing isomer proportions of (70 ± 6) %. Finally, this in situ NMR method is paving the way for rapid screening of innovative catalysts for sustainable NIPU synthesis.

5CC 5-membered cyclic carbonate NMR Nuclear magnetic resonance DBU 1,8-diazabicyclo[5.4.0] undec-7-ene TBD 1,5,7-triazabicyclo[4.4.0]dec-5-ene Ea Activation energy TU 1-(3,5-bis(trifluoromethyl)phenyl)-3-butylthiourea k Am Aminolysis rate constant TU - TU anionic form NIPU Non-isocyanate polyurethane