Sulfuric acid is known to catalyze ether cleavage, leaving both sides of the split molecule terminated with OH groups . All the carbon atoms participating in the ether bonds resulting from SU-8 polymerization are sp 3 hybridized. This is relevant because sp 2 hybridized carbon atoms participating in aromatic rings are partially protective against acid induced ether cleavage, so SU-8 can a priori be expected to be susceptible to depolymerization in sulfuric acid. But exposure of SU-8 to sulfuric does not result in depolymerization and dissolution of the polymer, much to the contrary SU-8 hardens, blackens, and cracks, making a complete clean up even more difficult. A drastic change in the reactivity of SU-8 in sulfuric is observed after exposure to dimethylamine. While it is difficult to determine the exact role played by dimethylamine, the initial rationale for using this chemical was the well known tendency of amines to link with epoxide functional groups (Fig. ). While molecules with multiple exposed N-H bonds are often commercially used for inducing cross linking of monomers with epoxide functional groups, it was foreseen that a small molecule with a single available N-H bond would terminate the polymer chain avoiding further polymerization during subsequent processing. Dimethylamine is the smallest molecule meeting this requirement. So dimethylamine can be expected to be protective against further polymerization when the SU-8 is exposed to sulfuric. The highly reactive carbocations resulting from epoxide polymerization can also be expected to be a reaction site for dimethylamine. Such reaction is strongly favoured by a large reduction in the Gibbs free energy as shown in Fig. . The drastic and permanent change induced by exposure to dimethylamine in the depolymerization rate of SU-8 when reacting with sulfuric acid suggests that dimethylamine is also directly involved at the ether cleavage reaction site. The weaker links in the polymer backbone are the ether bonds immediately adjacent to a carbocation and in the vicinity of an hydroxyl group as shown in Fig. . Furthermore, the fact that previous exposure of SU-8 to dimethylamine suffices to permanently change the reactivity of SU-8, led us to hypothesise that dimethylamine reacts with the carbocations in the SU-8 backbone, facilitating the ether cleavage in sulfuric acid. This hypothesis has been tested by quantum mechanical calculations of the energetics of the reaction pathway. It is important to underscore the limitations this type of calculations: the results, summarized in Figure : In our SU-8 removal protocol, dimethylamine reacts with the remaining epoxide groups, inhibiting the further polymerization that can otherwise be expected under acidic conditions. Fig. , are consistent with the proposed hypothesis, but this does not confirm the hypothesis as valid, it merely serves to gain confidence in its validity, as only a few of all the possible reaction pathways can be explored, and only thermodynamic results on stability are easily achievable, results on reaction kinetics being much more challenging to obtain. The cleavage of ether linkages in sulfuric acid has been studied by Sturgeon et al. with quantum mechanical calculations and experimental measurements of reaction kinetics of model molecules. All of the ether bond cleavage reaction pathways studied by Sturgeon et al. start with protonation of an hydroxyl group in the vicinity of the target ether bond. In our case, protonation of the hydroxyl group is hindered by Coulomb repulsion due to the presence of the carbocation in the immediate vicinity of the hydroxyl group and the target ether bond, with a free energy cost of 3.77 kcal/mol as deduced from our DFT calculations. Our calculations also reveal that the attachment of dimethylamine at the carbocation site is energetically very favourable (-29.87 kcal/mol), and results in a threefold reduction of the energy barrier for hydroxyl group protonation (0.92 kcal/mol vs. 3.77 kcal/mol). Hydroxyl protonation after dimethylamine attachment leads to an unstable intermediate product with one positive charge at each side of the ether bond, and the electrostatic repulsion between these two charges spontaneously rips apart the ether bond with a free energy change of -13.72 kcal/mol.