In order to investigate the gelation kinetics of the cross-linking reaction between 3 and 5 according to Scheme 3, time-dependent in-situ 1 H NMR measurements of the reacting mixtures were carried out at 25, 40, and 60 °C in THF-d8 at a concentration of 70 g L -1 . In the following, these networks will be referred to as CN25, CN40 and CN60. For each measurement, corresponding volume fractions of two stock solutions of the star polymers 3 and 5 were poured into an NMR tube and brought to the desired reaction temperature within ~5 min. The reaction was equimolar with respect to the reacting terminal groups. Selected spectra recorded during the reaction at 40 °C are shown in Figure . For clarity, only the region of aromatic protons is shown. The intensities of the signals at 9.5 ppm (H7' of CN) and at 8.54 ppm (H10 of 3) were used to calculate the conversion p of the cross-linking reaction (see also SI Figure ). The signal assignment is based on the spectra of the corresponding star block copolymers, as described recently. In Figure , the H7' signal of the formed benzamide group appears already after 3 min, indicating that the reaction begins immediately after the solutions are poured together. However, the reaction is of intermediate rate and could be well followed up to conversion of p ~0.9 for CN40 and p ~ 0.8 for CN25 and CN60. Continuing the reaction outside the spectrometer reveals that complete conversion could not be achieved under the given reaction conditions, even after a total reaction time of three For a more detailed analysis of kinetics, we consider that the reactive groups are stoichiometrically balanced, [3] 0 = [5] 0 . In this case, kinetics can be written as