for the low t data with p < 0.4 in order to determine an effective time offset t0. This offset accounts for sample handling and temperature equilibration in the NMR spectrometer in the initial period. For the three graphs in Figure , we have shifted each data set along the time axis by the corresponding 𝑡 0 and plotted against equation (5). Up to p ~ 0.6, the reactions closely follow the predicted ideal reaction kinetics. Using the obtained k values at temperatures of 25, 40, and 60 °C from Table , the Arrhenius activation energy Ea of 21.8 ± 0.9 kJ mol -1 was determined. The corresponding ln k vs. 1/T plot and the associated calculation of Ea are shown in the SI in Chapter 11 (Figure ). A significant slowdown of kinetics is visible at higher conversions. This observation is equivalent to the behavior of the simulation data shown in the SI Chapter 12. Such a slowdown in a recombination reaction of two species at stoichiometric conditions is a signature of composition fluctuations. These become stationary after gelation as the star polymers are rapidly incorporated into the gel (see SI Figure ). Therefore, the slowdown also is a measure for the quality of the mixture. The onset of this process occurs at almost the same conversion as in the perfect mixtures of the simulations, indicating near perfect mixing conditions in the experiment. Regarding the NMR spectra in Figure , it is noticeable that the signal widths widen significantly with increasing crosslinking. This is caused by the reduced mobility of the segments in the network.