Atmospheric Pressure Plasma‐Assisted Surface Modification of <scp>PLA</scp> Films via Acrylic Acid Polymerization

ABSTRACT Polylactic acid (PLA) films have limited surface functionality, which restricts their use in biomedical and packaging applications. In this study, polylactic acid (PLA) thin films were surface‐modified via plasma polymerization of acrylic acid (AAc) to improve their hydrophilicity and functional group density for potential applications in industry such as active packaging. The process was performed using an atmospheric Dielectric Barrier Discharge (DBD) plasma system in two‐step process: argon plasma pretreatment followed by plasma polymerization of AAc. The effects of pretreatment time (30–120 s), AAc monomer concentration (10%–90%), and post‐treatment time (0–10 s) were systematically evaluated. The density of carboxylic acid (COOH) groups was quantified using the toluidine blue O (TBO) assay, with the highest uptake obtained at 120 s pretreatment, 30% AAc concentration, and 5 s post‐treatment. ATR‐FTIR analysis confirmed the incorporation of COOH and OH functional groups on the surface. Water and ethylene glycol contact angles were measured to assess surface wettability, and surface free energy was calculated using the Owens‐Wendt method. FE‐SEM images revealed uniform poly(acrylic acid) layer formation at shorter post‐treatment durations, and AFM analysis confirmed increased surface roughness correlated to enhanced hydrophilicity. The results demonstrate that optimized plasma polymerization can effectively functionalize PLA surfaces, enhancing their surface functionality and hydrophilicity, which may enable further functionalization for industrial applications such as active packaging.