studied infiltration of Al2O3 into PMMA and PLC, demonstrating that the interaction of PCL with metal precursors is very strong, even though its ester functional groups are seemingly similar to those present in the more weakly interacting PMMA polymer. Similarly, Padbury et al. reported that nearly 100% of the reactive groups in the PLC matrix react with TMA molecules, leading to a significant amount of Al2O3 incorporated into the polymer matrix during a single SIS cycle. Finally, Motta et al. reported homogeneous growth of Al2O3 throughout the entire thickness of a 30 µm thick PBS freestanding membrane. Moreover, Al2O3 mass uptake in PBS thin films was demonstrated to be much higher than in standard PMMA films, under the same process conditions. Consequently, having the same functional groups does not guarantee strong infiltration of the inorganic phase into the polymer matrix but more understanding of the details of precursor infiltration is required.