The lack of regiocontrol in the aminolysis of 5CC, i.e. the formation of mixtures of primary, (OH)I, and secondary, (OH)II, alcohols, is a general noted drawback for PHU synthesis . Authors have tentatively addressed the problem by designing suitable monomers. Among them, the group of Endo et al. have demonstrated that the selectivity in favor of (OH)II formation can be increased by increasing the electron-withdrawing ability of the α-or β-substituents of the 5CC. More recently, Kleij et al. have demonstrated that 5CC with bulky substituents can be ring-opened under organocatalytic control (e.g. TBD) with a regioisomer excess up to >99% (e.g. (OH)II). However, to the best of our knowledge, all these methods were tested with model molecules. The preservation of the regiocontrol during the polymerization of bis-5CC derived from these model molecules has not been confirmed yet. More importantly, there are no existing methods to control the degree of regioregularity for the polymerization of a given bis-5CC structure, and thus to explore the impact of the regioregularity onto the properties of the resulting PHUs. As for stereoregularity in PHUs synthesis, it is nearly unaddressed in the literature. This challenge is relegated to the background due to the prevalence of side reactions and low molar masses issues. Yet, the methine carbon of 5CC are chiral centers (Scheme 1) that are inserted in the polymeric chains derived from them. Since the chirality of bis-5CC precursors is usually not controlled, their polyaddition with diamines results in stereo-irregular PHUs. To our knowledge, only one study explored the influence of the stereochemistry of a bis-5CC onto its reactivity and the properties of the resulting PHUs. It was recently reported by Maggliozi et al., who used a procedure of enantioselective crystallization to isolate two crystal structures of diglycerol dicarbonate (DGDC, Scheme 1): the enantiopure meso-DGDC, (R,S), and the racemic mixture of (R,R) and (S,S) DGDC. These two crystals were polymerized in bulk with various diamines (110 °C). Interestingly, the characterizations of the resulting PHUs suggest a slight impact of the stereochemistry of DGDC onto the chain insertion efficiency and on the regioregularity of the chains. PHUs derived from meso-DGDC exhibit slightly higher molar masses, while PHUs obtained from the racemic mixture of (R,R) and (S,S) DGDC come with higher contents of (OH)I. Despite these intriguing results, the procedure to isolate the DGDC stereoisomers is tedious, preventing larger-scale synthesis and systematic studies. Herein, we propose to use enantiopure bis-5CC obtained from the direct carbonatation of sugarbased butadiene tetraols that are enantiopure themselves, namely (i) meso-erythritol and (ii) its (S,S) diastereoisomer, (L)-threitol (Scheme 1). Recently, Dannecker and Meier introduced a simple and sustainable method for the organocatalytic carbonatation of meso-erythritol in the presence of dimethyl carbonate used both as a reagent and a solvent [8]. The corresponding erythritol di(carbonate) (EDC) retains the stereochemistry of the starting tetraol and is obtained in very high yield (90%). We propose to apply the same procedure to (L)-threitol, to obtain a set of two optically pure stereoisomers of butadiene dicarbonates: EDC and its (S,S) diastereoisomer threitol di(carbonate) (TDC). The aminolysis of EDC and its use for the synthesis of PHUs is already well documented in the literature. In particular, several authors reported the straightforward aminolysis of EDC in very mild conditions, including room temperature. This remarkable feature was attributed to the strong mutual inductive effect that the vicinal 5CC exert on each other. However, to the best of our knowledge, there is no report regarding the quantitative measurement of the kinetics rate of the reaction. Schmidt et al. valorized the very high reactivity of EDC for the synthesis of high molecular weight PHUs in bulk, i.e. at high temperature (100 °C), but the reactions are so fast in these conditions, that it is virtually impossible to study their kinetics. Here, we perform a comprehensive study of the aminolysis reaction of EDC and TDC in solvent and at room temperature. The experimental results, supported by DFT calculations, indicate that the kinetics and the regio-orientation of the ring opening of the 5CC are very dependent on the stereochemistry of EDC and TDC respectively. Moreover, for both EDC and TDC, the kinetics rate constant of the aminolysis of the dicarbonate is two orders of magnitude larger than that of the mono-carbonate resulting from the first aminolysis reaction. We use this feature to develop a one-pot, two step polymerization procedure offering sequence-controlled PHUs. In the end, the comparative study of the two vicinal dicarbonates, e.g. EDC and TDC, provides a new family of PHUs with tunable sequence-and regio-regularity. The impact of the chain-regularity of the PHUs onto their thermal properties is investigated. In this work, erythritol di(carbonate) (EDC) was synthesized starting from (R,S) erythritol according to the procedure recently described by Dannecker and Meier (Figure , 84% yield). The same method was applied successfully to L-threitol, the (S,S) diastereoisomer of erythritol (93% yield). This is the first report of the synthesis of L-threitol di(carbonate) using this method. For sake of simplicity, it is called threitol di(carbonate) (TDC) in the rest of the paper. The structure of the two diastereoisomers was confirmed by NMR (Figure ). Moreover, monolithic crystals of EDC and TDC were analyzed by X-ray crystallography, indicating that the (R,S) and the (S,S) isomers are both monoclinic crystals. However, the space group of EDC is P21/n while TDC is associated to the P21 space group. Figure represents their tridimensional structure. The two carbonate cycles of EDC are located on either side of the butane skeleton, meaning that the carbonyl groups point in opposite direction. In the case of TDC, the two carbonate cycles are facing each other. The crystallographic data confirm that the stereochemistry of the dicarbonate is consistent with those of the starting tetraol. The melting temperature, Tm, of the two crystals were measured by Dynamic Scanning Calorimetry, DSC (see Figure ). The melting point of EDC, Tm = 169 °C, is higher than that of TDC's, Tm = 137 °C. These results confirm that the stereoisomery of bis(carbonate) impacts their thermal properties, as already noticed by Magliozzi et al. for the stereoisomers of DGDC.