Infiltration of Al2O3 into poly (methyl methacrylate) (PMMA) thin films using trimethyl aluminium (TMA) and H2O as precursors has been widely investigated and is commonly considered as a reference system in the scientific community. Variation of sorption, diffusion and reaction of TMA into this specific polymer as a function of processing parameters have been well studied. In particular, upon increasing the processing temperature, a progressive enhancement of TMA diffusivity is determined, but a concomitant reduction of TMA solubility and reactivity is induced, significantly decreasing the amount of TMA trapped into the polymer matrix. As a consequence, the effective incorporation of Al2O3 into the PMMA matrix is generally limited, irrespective of the processing temperature. Recent results have highlighted that several polymers, like poly(ethylene terephthalate glycol) (PET-G), polycaprolactone (PCL), poly (lactic acid) (PLA) and poly(butylene succinate) (PBS) exhibit significantly higher reactivity to TMA compared to PMMA . In particular, by monitoring the evolution of the film thickness during the infiltration process, Petit et al. demonstrated extremely efficient infiltration of Al2O3 into PET-G arising from the irreversible reaction of TMA with the polymer matrix which limits the out-diffusion of TMA. Biswas et al.