Effects of Femtosecond Laser‐Induced Microscale Surface Textures on the Properties of Poly(vinyl alcohol) and Chitosan Films

ABSTRACT

Femtosecond laser surface texturing was applied to solution‐cast poly(vinyl alcohol) (PVA) and chitosan (CS) films to evaluate changes in surface topography and associated properties without altering film formulation. Grid‐like microscale grooves were generated under the selected processing condition. Thickness measured using a contact gauge increased significantly for both films. Tensile strength was not significantly affected in either polymer. PVA elongation at break decreased significantly, whereas the change in CS elongation at break was not statistically significant. Water contact angles increased from 65.91° to 72.76° for PVA and from 78.18° to 82.82° for CS; both surfaces therefore remained hydrophilic but showed reduced immediate wettability. FTIR characteristic‐band positions remained largely unchanged, and spectral intensity differences were not used to infer changes in functional‐group concentration. UV–Vis transmittance also changed after texturing, but scattering limits quantitative interpretation. Antibacterial inhibition increased from 2.55% to 39.80% against Escherichia coli and from 13.28% to 18.49% against Staphylococcus aureus for PVA. For CS, inhibition was already above 90% before texturing and exceeded 98% after texturing. Residual acetic acid may have contributed to the high baseline inhibition of CS, whereas the additional increase was observed after laser texturing under otherwise identical film‐preparation conditions. Femtosecond laser texturing therefore modified surface‐related film properties, but further validation is required for practical active‐packaging applications.