PLA/AgNO₃ composites fabricated by stereolithography with improved mechanical and antibacterial properties

Abstract

The development of polymer composites with antibacterial functionality and improved mechanical performance has attracted increasing attention for applications requiring both structural integrity and microbial resistance. In this study, poly(lactic acid) (PLA) composites containing silver nitrate (AgNO₃; 1, 3, and 5 wt%) were fabricated by stereolithography (SLA) and characterized. SEM and EDX analyses confirmed the presence of silver within the PLA matrix, with relatively uniform distribution at lower contents and localized heterogeneities at higher loadings. FTIR results indicated that the chemical structure of PLA was largely preserved after AgNO₃ incorporation, with minor spectral shifts suggesting possible interactions with silver-containing species. TGA revealed a slight increase in the onset degradation temperature, from 315 °C for neat PLA to 321 °C for the composite containing 5 wt% AgNO₃. Mechanical testing showed improvements in both tensile and flexural properties with increasing AgNO₃ content, with tensile strength rising from 39.6 MPa to 55 MPa and flexural strength from 45.4 MPa to 76.7 MPa. Antibacterial tests demonstrated clear inhibition against Escherichia coli and Staphylococcus aureus, with stronger activity observed at higher AgNO₃ contents.