Surface modification of polymer and thin film via plasma treatment: A comparative study of nitrogen and Sulfur hexafluoride effects

The surface characteristics of polymeric materials significantly influence their applications in biomedical and industrial fields. This study examines the effects of nitrogen (N 2 ) and sulfur hexafluoride (SF 6 ) plasma treatments on polyvinyl chloride (PVC) and polytetrafluoroethylene (Teflon) to assess modifications in wettability, chemical composition, topography, and antibacterial behavior. SF 6 plasma improved fluorination by creating CF 3 -rich surfaces, while nitrogen plasma introduced polar functionalities like C– N, C = O, and O–C = O, according to X-ray photoelectron spectroscopy (XPS) study. Following plasma treatments, atomic force microscopy (AFM) studies revealed an increase in surface roughness; nitrogen plasma significantly roughened the surface, especially for PTFE. Increased polar surface groups following nitrogen plasma resulted in increased hydrophilicity, while fluorine enrichment and surface texturing following SF 6 plasma resulted in increased hydrophobicity, according to contact angle analysis. These tendencies were confirmed by surface free energy calculations, which revealed a preponderance of dispersive interactions after SF 6 plasma and an increase in the polar component after nitrogen plasma. Antibacterial testing showed no effective bacterial suppression in spite of these significant physicochemical alterations. The lack of bactericidal chemical capabilities and the potential encouragement of bacterial adhesion by increased surface roughness are the reasons for the lack of antibacterial activity. Overall, plasma treatments successfully changed the wettability and surface chemistry of PVC and PTFE; nevertheless, additional antimicrobial chemical inclusion or the creation of sharper nanoscale surface structures would be necessary to achieve antibacterial functionality.