Preparation and characterization of maleimide-polystyrene/SiO₂-Al₂O₃ hybrid nanocomposites by an in situ sol-gel process and its antimicrobial activity

Inorganic-organic nanocomposites have unlocked new opportunities in the design of innovative materials and compounds with enhanced and unique properties, based on soft chemistry. In the present study, a hybrid nanocomposite of maleimide-polystyrene (PSMA) with SiO₂ and Al₂O₃ (PSMA-SA) was synthesized by means of the sol-gel approach in the presence of γ-aminotriethoxysilane (γ-APTES), in which tetraethoxysilane (TEOS) and aluminum isopropoxide (AIP) were used as precursors. The Michael reaction led to bonding between the PSMA and SiO₂-Al₂O₃, giving a stable cross-linked network that prevented aggregation and mechanical mixing of the nanoparticles. XRD and FTIR analysis confirmed the effects of the coupling agent in promoting the Michael reaction. Thermal properties of the hybrid nanocomposites were tested through TGA and DSC. SEM, TEM and optical tests confirmed the controlled morphology and optical transparency of the composites. Additionally, the hybrid nanocomposites showed excellent solvent resistance and antimicrobial activity against pathogenic bacteria such as Bacillus cereus and Escherichia coli.