Surface DBD plasma functionalization of the interior of PVC and PTFE tubes: effects on surface properties and environmental safety assessment of leaching

This study investigates the internal surface modification of polytetrafluoroethylene (PTFE) and poly(vinyl chloride) (PVC) tubes using a liquid-electrode surface dielectric barrier discharge (SDBD) plasma system. The approach addresses the “hollow body problem” by enabling uniform treatment of narrow internal geometries without vacuum conditions, while maintaining temperatures below the thermal deformation limits of the polymers. Water contact angle measurements showed successful conversion from hydrophobic to wettable surfaces (WCA ≈ 65–75°) with stable properties over 25 days, while X-ray photoelectron spectroscopy confirmed significant surface chemical restructuring, including approximately 50% fluorine replacement in PTFE. Furthermore, High-Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC/MS) enabled an integrated environmental safety assessment. The analysis revealed trace perfluorocarboxylic acids (C3–C8) originating from PTFE as process-related byproducts that remained non-leachable after treatment. For PVC, the study differentiated between temperature-induced diffusion of bis(2-ethylhexyl) phthalate (DEHP) and the formation of phthalic acid as an indicator of plasma-induced oxidative degradation. Ultimately, these results demonstrate that SDBD plasma treatment is an effective method for modifying polymer tube surfaces while preserving material integrity and limiting hazardous substance release, providing critical insights into the environmental and biomedical safety of polymer plasma treatment systems to support their potential use in medical and related applications.