Sequential Infiltration Synthesis of Al2O3 in PMMA Thin Films: Temperature Investigation by Operando Spectroscopic Ellipsometry

Sequential infiltration synthesis (SIS) is a scalable and valuable technique for the synthesis of organic-inorganic materials with several potential applications at the industrial level. Despite the increasing interest for this technique, a clear picture of the fundamental physicochemical phenomena governing the SIS process is still missing. In this work, infiltration of Al2O3 into thin poly(methyl methacrylate) (PMMA) films using trimethyl aluminum (TMA) and H2O as precursors is investigated by operando dynamic spectroscopic ellipsometry (SE) analysis. The TMA diffusion coefficient values at temperatures ranging from 70 to 100 °C are determined, and the activation energy for the TMA diffusion process in PMMA is found to be Ea = 2.51 ± 0.03 eV. Additionally, systematic data about reactivity of TMA molecules with the PMMA matrix as a function of temperature are obtained. These results provide important information, paving the way to the development of a comprehensive theory for the modeling of the SIS process.