The goal of our charge derivation procedure is to obtain a set of charges that is able to describe any polymerization state n of DGEBA (Scheme 2a), the amine hardener as well as any state of curing (Scheme 2b). The polymeric character of the system suggested a fragment-based approach, in which the DGEBA and DDS molecules were broken down into pieces ("Blocks") equipped with capping groups at the extremities (Scheme 3). Charges for each capped block fragment were derived by imposing two simultaneous conditions: both the block itself and a DGEBA molecule of any length, resulting from linking the blocks together and removing the capping groups, had to be charge neutral. For this purpose, appropriate intermolecular charge constraints (C1-C6) were applied during charge derivation. More specifically, partial atomic charges were derived following the RESP methodology , as implemented by the RED.III.5 tools 41 using geometry optimized molecular structures and ESPs obtained with Gaussian 16 at the HF/6-31G(d) level of theory. The aromatic ether groups of DGEBA were modelled by -CH3 capping groups on the PHE fragment together with -OCH3 capping groups on the terminating EPX/EPO block fragments, to account for the chemical environment occurring after those blocks are joined together. The DDS molecule was not further split into fragments and used as a single unit during charge derivation. One additional block (OPO) is necessary to describe the covalent network during and after the curing reaction (Scheme 3). OPO, the terminal fragment of a DGEBA molecule resulting from a cross-linking event, required charge constraints compatible with the overall charge neutrality of the unreacted system. With this definition of the OPO and DDS fragments, we can describe all six possible curing states of DDS, obtained by combining either a primary or secondary amine on one side of the hardener with another primary or secondary amine on the other side. Thanks to the combination of inter-and intramolecular charge constraints (see Figure ), this drastically simplifies the number of necessary fragments and allows the usage of the reaction schemes depicted in Schemes 4 and 5 for all curing states (details on this procedure follow in the next sections). The final partial atomic charges for all blocks fragments are reported in Scheme S1.