Four specific states were chosen to best represent the initial, TS, and final states of the depolymerization reaction with the knowledge that these could not be comprehensive to all the bond rotations and extensions. The exact, optimized configurational response along the polymer chain during the TS cannot be accurately captured as it is a specific energetic path in the potential landscape. As electron withdrawing effects of pendent functional groups drop off significantly along the polymer backbone, we only examine a single repeat unit for comparison of qualitative energetics between ab initio and semi-empirical methods. Additionally, using longer chains would need to be frozen in ab initio calculations to make them tractable while in semi-empirics they would be extremely susceptible to fall into local minima. Keeping a longer polymer chain would also necessitate freezing atoms, and we would only be able to compare the solvent effects for larger materials with a higher degree of polymerization (DPn). The results of the DFT optimized barriers from 1a-g (Fig. ) are shown Fig. , with the average absolute enthalpic energy barriers ranging around 40 kcal/mol (Fig. ) for an uncatalyzed ring closure to re-form a cyclic carbonate (Fig. ). From the absolute enthalpic barriers alone it is challenging to ascertain a clear trend in terms of the computed volume or solvent interaction energy. Instead, by plotting the difference in the energy barrier or solvent interaction energy for each compound relative to 1a-which bears only hydrogen atoms attached to its C2 carbon-we can observe changes in the energy barrier which may correspond to the steric and electronic effects of the substituents at the C2 carbon in conjunction with respective solvent environment (Fig. and Fig ). From these plots, it is apparent that using acetonitrile (MeCN) as a solvent universally lowers the relative enthalpic barrier to depolymerization by over 2 kcal/mol in some instances (Fig ). In contrast, use of toluene (PhMe) or tetrohydrofuran (THF) as solvents lead to an increase of the relative energy up to nearly 4 kcal/mol. Similar trends are also observed in the DFT computed enthalpic barriers where MeCN typically gave the lower enthalpic barrier heights, albeit that the DFT computed barriers are approximately 1-5 kcal/mol higher relative to the corresponding DFTB computed ones (Fig. ). Analogous trends are seen also with the solvent interaction energy, where again use of MeCN universally lead to lower values (Fig. ). With the computed volume relative to 1a (Fig. ), no apparent correlation was observed with changes in relative solvent interaction energy or relative enthalpic barrier height across all solvents. Prior experimental work had observed trends in the depolymerization of many of the same or similar monomers under thermodynamic control, where sterically bulkier substituents at the C2carbon in general favored higher yields of the corresponding cyclic carbonate (see Supplementary Fig. for summarized literature examples). Based on the computational enthalpic barrier data presented here, the correlation between the steric size of the C2-substituents and either the absolute or relative enthalpic barriers is less clear when MeCN is used as solvent whereas PhMe and THF do show in general decreasing barrier heights from 1c to 1g as the molecular volume increases (Fig. and). This is roughly consistent with prior thermodynamic trends observed when using THF and suggests when using these solvents bulkier substituents give both a faster rate and stronger thermodynamic driving force. While the overall interrelationships between solvent, structural features, and enthalpic barrier are complex, the overall trends with the solvent interaction energies, enthalpic barrier height, and solvent identity are more clear and correlate well with experimental observations on the solvent effect on the Tc. In reported experimental work, nonpolar solvents such PhMe resulted in higher Tc values compared to polar aprotic solvents such as MeCN. This trend is also generally observed in the DFTB absolute and relative enthalpic barriers where MeCN is utilized, suggesting that MeCN not only lowers the Tc, but also accelerate the reaction as well. From published experimental results, polar aprotic solvents also tend to give better results in terms of conversion to monomer whereas nonpolar solvents give poorer results (Supplementary Fig. ). As the thermodynamic interpretation of the reported solvent-solute interaction is the contribution to the free energy from vacuum to solvated, a negative contribution from MeCN suggests the molecules are able to achieve tighter conformations. MeCN is allowing conformations which would typically require a higher temperature to access, likely by screening intramolecular interactions.