After 2 min of reaction, the molecular mass distribution is eluted between 8 and 11 min, compared with 7.5 and 10 min initially found for the raw polymer, meaning that the average molar mass of PBPAC has slowly decreased, from approximately 32000 g•mol -1 to 23000 g•mol -1 . After 5 min of reaction, the molecular mass distribution is eluted between 9 and 11 min, indicating a further reduction in mass, reaching approximately 4000 g•mol -1 . After 15 min, elution times ranged from 9.7 min to 12 min. Finally, the 30 min and 2 h samplings lead to a similar mass distribution, ranging from 10 min to 12 min, reaching approximately 1000 g•mol -1 . The exact values are presented in the Table . Interestingly, the elution profile is found to slowly shift from the classical mass distribution centered around the average DP, towards a massif with two main peaks (at 10.76 min and 11.09 min respectively), reflecting the appearance of two major species, or families of species. Note that, as previously observed, the peak that elutes at 11.09 min is close to the retention time of BPA. However, for the same reason as mentioned previously, the products formed cannot be confirmed based on SEC analysis alone. Also, after 30 min, it is no longer the elution time that varies, but only the width and intensity of these two peaks, showing that degradation seems to converge towards these two majority species in the allotted time. It should be noted, however, that the peak at 11.09 min is increasing the most, and thus seems to be affected most from the continuing degradation as it can be expected from our previous findings with total methanolysis. Also, regarding the peak at 10.76 min, it should be noted that as its intensity seems to vary only slightly, it could suggest either the creation of a transition species, which is consumed at a rate equivalent to that of its formation, or a species produced at a given moment in the de-polymerization process and which proves to be fairly stable over the measurement time. However, given that the methanolysis conditions have been modified very little, and that in the case of the total methanolysis only the peak at 11.09 min was again observed at the end of the reaction, we can logically assume that this transitory peak would effectively disappear if the deterioration were allowed to continue over a longer period. Interestingly, the absence of any low-mass peaks before 10 min of degradation suggests that the depolymerization mechanism is most probably endo and not exo, which supports the previous hypothesis, the peak at 10.76 min probably being an oligomer, or family of oligomers, of a specific polymerization degree that serves as an intermediate species towards more complete degradation into BPA. This hypothesis can be confirmed by the expected increase in polydispersity measured in the first few minutes, reflecting the random cleavage of polymeric bonds. Indeed, the increase in polydispersity rose from 1.5 to 1.6 after 2 min, then to 2.2 after 5 min. From this, we can then calculate the percentage of depolymerization, since the method for calculation effectively depends on the type of cleavage. In our case, the (2) 𝑛 = % ! % -1 For the calculation of the number of cleaved bonds, the Mn of the polymer was taken into account. The results obtained for the depolymerization percentages calculation are listed in Table . As observed, the percentage of degradation increases from just 0.4 % after 2 minutes of reaction, to 33 % after 2 hours. This indeed correlates to the decrease in Mn and Mw. In addition, the example shows that in the case of endo degradation, from as little as 0.4 % depolymerization, SEC is able to confirm that degradation has taken place. Using the results presented in Table , the depolymerization detection limit can then be calculated to 0.06 %, which makes SEC an extremely sensitive analytical technique in our conditions. It then appears to be an indispensable analytical method for confirming that degradation has taken place, especially when the percentage of degradation is low, and for determining changes in MWD during depolymerization. However, as in the case of total depolymerization, SEC still struggles to identify the products formed, and in our case, also the transitional species.