As a last complementary NMR analyses, the synthesized oligoPBAT-dithiol-protected was also analyzed by P NMR (Figure in SI). No peak was obtained apart from excess TMDP, cholesterol and water, which confirmed the absence of residual -OH chain ends with the thiol protection. Finally, oligoPBAT-diol and oligoPBAT-dithiol-protected were analyzed by DSC (Figure ). OligoPBAT-diol melting resulted in a two-step endothermic peak between 140 and 180 °C, approximately. However, contrary to some previous results on PBAT-based structures [11], an endothermic peak assigned to the melting of short chains based on butylene adipate (BA) units was not recorded. Surprisingly, the endothermic peaks of oligoPBAT-dithiol-protected were completely different, with a main broad melting peak at 105 °C, and another endothermic peak at 54 °C, with a corresponding weak crystallization peak during cooling around 45 °C. The fact that only the thermogram of oligoPBAT-dithiol-protected contained these peaks need additional investigations at this level, because the esterification of chain ends was not expected to yield low-melting products. Consequently, the presence of solvent or some by-products, which were not detected by FTIR and NMR, cannot be fully excluded. In all the cases, this specific behavior needs further investigation to be fully clarified. On the other hand, the increase of Tg from -34 to -4 °C was expected and fully explainable by the addition of rigid aromatic groups at chain ends. The effect of rigid aromatic groups on the Tg has largely been studied in the literature on different macromolecular architectures . Next steps will be the optimization of these systems towards upscaling steps. Then, the thiol groups of OligoPBAT-dithiol-protected were deprotected with an excess of 1-propanethiol, since the base-catalyzed aromatic nucleophilic substitution requires a large excess of 1-propanethiol to adequately drive the equilibrium . The deprotected oligoPBATdithiol was first analyzed by FTIR (Figure ). The band at 2573 cm -1 was assigned to S-H stretching, with a low intensity as usually reported for thiols . Two weak residual bands assigned to NO2 asymmetric bending and C=C stretching of the dinitrobenzene groups were recorded. It could be an indicator for some residual protected chain ends, although the other characteristic bands completely disappeared. The presence of some residual protected chain ends was confirmed by 1 H NMR (Figure ) with the presence of small residual peaks assigned to the protons j, k, l and m, from the protected chain ends. However, the success of the thiol deprotection was clearly confirmed with the appearance of a doublet at 3.25 ppm assigned to the CH2-SH protons. By calculating the weighted ratio of this peak integral to the peak integral of the residual peak j, the percentage of deprotected chain ends was found to be very high, around 94 mol%. The thiol content determined by quantitative 1 H NMR was 1.1 mmol g -1 , corresponding to a 66% conversion rate of oligoPBAT-diol's OH to thiol groups. C APT NMR further confirmed the chemical structure of the synthesized oligoPBAT-dithiol with the appearance of a new peak at 26.6 ppm, labelled s, assigned to CH2-OOC-CH2-SH carbons (Figure ). No peaks corresponding to residual protected chain ends were obtained in this case, since the peaks m, n, o, p and q were completely removed. The peak m of oligoPBAT-dithiolprotected at 66.0 ppm was replaced by the peak s, assigned to CH2-OOC-CH2-SH carbons, at 65.2 ppm. The presence of thiol groups at chain ends was fully confirmed by 31 P NMR with the appearance of two overlapping peaks at 214.63 and 214.65 ppm, corresponding to the two types of -SH chain ends, i.e. SHAA-BDO and SHTA-BDO, similarly to the -OH chain ends of oligoPBATdiol (Figure in SI). P also confirmed that the analyzed thiol groups were at chain ends and not residual 1-propanethiol, of which -SH peak in 31 P NMR was recorded at 218.37 ppm (Figure in SI). Finally, the DSC thermogram of oligoPBAT-dithiol was obtained as expected, with a broad melting endothermic peak between 100 and 140 °C, a crystallization peak at 94 °C. In a very consistent way and in contrast to the results presented on oligoPBAT-dithiol-protected, we can show in this case, a Tg decreased from -4 to -28 °C, due to the removal of the rigid aromatic rings at chain ends (Figure ).