Multifunctional applications of alumina (Al₂O₃) nanofiller-doped PMMA films: evaluation of nanocomposite films for electronic, optoelectronic, and environmental photocatalytic applications

Polymethyl methacrylate (PMMA) nanoparticles (NPs) integrated with alumina (Al₂O₃) nanocomposite films were prepared using a solution-casting method. XRD, FTIR, SEM, and TEM analyses were used to characterize the obtained composite films. The study investigated the impact of Al₂O₃ nanoparticles (Al₂O₃ NPs) on the optical characteristics of the PMMA polymeric matrix using UV–Vis-NIR optical spectroscopy. The fabricated films demonstrated unique light-blocking capabilities within a range of 190–275 nm. Optical energy gaps changed dramatically when Al₂O₃ nanoparticles were added to polymeric chains of PMMA. The direct optical gap decreased from 4.95 to 4.85 eV, while the indirect optical gap decreased from 4.78 to 4.5 eV. The behavior of the Urbach energy (E_U) increases with increasing Al₂O₃ NP loading. The study demonstrated remarkable optical limiting capabilities using two laser sources with wavelengths of 632.8 nm and 533 nm. The inclusion of Al₂O₃ NPs resulted in an enhanced dielectric constant, indicating increased polarization of particles within polymeric films at reduced frequencies. As Al₂O₃ NPs content and frequency increased, AC conductivity also increased. PMMA/Al₂O₃ composite films demonstrated a photocatalytic degradation efficiency of 96.15% and a reaction rate constant of 0.0284 min⁻¹ in degradation of RhB dye with (1.66 wt.%) alumina content exhibited the highest efficacy under UVA light. ^·OH radicals are the reactive species responsible for the degradation of RhB dye. These promising outcomes suggest the potential multifunctional applications of Al₂O₃/PMMA nanocomposite films, including their use as laser optical limiters and photocatalytic membranes for wastewater treatment, reinforcing their utility in various domains.