The chemical structure of this oligoPBAT-dithiol-protected was first assessed by FTIR. The FTIR spectrum of oligoPBAT-dithiol-protected was compared with the spectra of oligoPBATdiol and DNTPAA (Figure ). All bands from oligoPBAT-diol were still present on the FTIR spectrum of oligoPBAT-dithiol-protected, except the broad band centered on 3411 cm -1 , corresponding to O-H stretching, due to the esterification of the OH chain ends. Only a very weak residual band was observed at 3414 cm -1 . The two new bands at 3114 and 3090 cm -1 were assigned to DNTPAA's Caromatic-H stretching vibrations. The other new bands at 1592, 1520 and 1340 cm -1 , also present on the FTIR spectrum of DNTPAA, were assigned to C=C stretching, NO2 asymmetric bending and NO2 symmetric bending, respectively . The analysis of the FTIR spectrum of oligoPBAT-dithiol-protected thus confirmed the effective functionalization of the chain ends of oligoPBAT-diol by esterification. The chemical structure of OligoPBAT-dithiol-protected was also deeply analyzed by several and complementary NMR techniques. Firstly, 1 H NMR unequivocally confirmed the success of the esterification, with the disappearance of the triplets at 3.66 and 3.72 ppm, assigned to CH2-OH protons, and the appearance of two overlapping singlets at 3.84 ppm, labelled j and assigned to OOC-CH2-S-Ph protons (Figure ). The peaks at 9.07, 8.38 and 7.71 ppm were assigned to the protons k, l and m of the grafted 2,4-dinitrobenzene rings, respectively. The peaks j, k, l and m were integrated and the ratios of the area of the peak j to the peak areas of k, l and m were equal to 2.2, 2.0 and 2.0, respectively. This confirmed that all the detected dinitrobenzene groups were bonded to PBAT oligomers and did not belong to residual free DNTPAA. C APT NMR was also used. On the corresponding oligoPBAT-dithiol-protected spectrum, three peaks at 121.8, 127.3 and 127.5 ppm were obtained and assigned to the tertiary carbons of the 2,4-dinitrobenzene chain ends (Figure ). They were shifted compared to their counterparts obtained on the 13 C APT NMR spectrum of DNTPAA at 121.3, 127.5 and 128.4 ppm, respectively (Figure ), due to the esterification of the carboxylic acid (COOH) groups. The quaternary carbons of the 2,4-dinitrobenzene chain ends were not detected, due to the higher relaxation time of the quaternary carbons . The success of the esterification was also confirmed by the disappearance of the peaks at 29.2 ppm and 62.3 ppm, corresponding to the carbons CH2-CH2-OH and CH2-CH2-OH, respectively, that were obtained on the spectrum of oligoPBAT-diol. Instead, new peaks, labelled m and q, appeared at 66.0 and 35.1 ppm and were assigned to the carbons CH2-OOC-CH2-S-Ph and CH2-OOC-CH2-S-Ph, respectively. In the same way, the peaks assigned to carbons b' and c' of oligoPBAT-diol were shifted from 65.2 to 66.0 ppm and from 64.1 to 64.7 ppm, respectively. 1 H-15 N HMBC NMR was also used to analyze the synthesized oligoPBAT-dithiol-protected since nitrogen-based DNTPAA was used in the esterification step. In this way, DNTPAA was first analyzed to obtain reference spots (Figure ). J and 4 J couplings were obtained between the nitrogen atoms of the nitro groups and the three aromatic protons, as detailed in Table in SI. The signals were obtained as expected and in accordance with the 1 H NMR spectrum obtained beforehand (Figure ). The coupling between Hf and NⅡ generated a double spot due to the multiplicity of the peak of Hf in 1 H NMR, which is a doublet of doublets. NⅠ and NⅡ could not be clearly distinguished due to apparently very similar chemical shifts. The spot at {δH = 1.20 ppm; δN = 336.9 ppm} was assigned to a 3 J N-H coupling of residual TEA, as supported by 1 H NMR (Figure ). OligoPBAT-dithiol-protected was then also analyzed by 1 H-15 N HMBC (Figure ). The obtain spots were similar to the ones obtained on the 1 H-15 N HMBC spectrum of DNTPAA, with some shifts linked to the esterification step (Table in SI), with reduced intensity due to the lower content of nitrogen atoms. Thus, 1 H-15 N HMBC confirmed the presence of dinitrobenzene groups in the chemical structure of oligoPBAT-dithiolprotected.