Due to the presence of two types of oxygen atoms in the PPA backbone, in addition to the fact that H tends to protonate oxygen atoms easily, depolymerization can occur through both endcap cleavage and protonation of oxygen atoms present in the backbone. For this reason, polymer chemists tend to use endcaps rich in oxygen atoms to accelerate depolymerization rate. For example, Moore and co-workers reported the use of a specific ion coactivation (SICA) effect that allowed the ion and acid coactivated-triggered depolymerization of a cyclic PPA microcapsules at the solid/liquid interface of the polymer and solution.