Overall, data in the literature suggest that the limited reactivity of TMA with the PMMA matrix is more the exception than the rule. Interestingly, all these polymers are characterized by the presence of ester groups along the main polymer chain that are expected to act as reactive sites for TMA during the SIS process, but the work discussed above demonstrates that the presence of ester groups alone in the polymer is not sufficient to drive the SIS chemistry and other factors will also be important.