Effect of oxygen plasma-treatment on surface functional groups, wettability, and nanotopography features of medically relevant polymers with various crystallinities

The surface properties of polymeric biomaterials play a crucial role in their biocompatibility and performance. This study explores the application of cold oxygen plasma treatment as a versatile technique for surface modification of polymeric materials with different degrees of crystallinity: crystalline high-density polyethylene (HDPE), crystalline-amorphous poly(chloro-paraxylylene) (parylene C), and amorphous aromatic polyetherbased polyurethane (PU). The investigations focus on the generation of surface functional groups and hydrophilicity, as well as nanotopography. X-ray photoelectron spectroscopy (XPS) analysis confirmed the generation of oxygen-containing functional groups, resulting in controlled wettability (water contact angle), while atomic force microscopy (AFM) showed topography modifications in the nanoscale. At the same time, it was revealed that oxygen plasma treatment did not affect the bulk properties (confirmed by TG and XRD). The effects of the same plasma treatment conditions varied significantly among the different polymers studied, depending on their crystallinity. This was discussed in terms of the preferential etching of amorphous regions in the polymeric structures. The findings emphasize the advantages of oxygen plasma treatment for tailoring the surface properties of polymeric biomaterials, highlighting its significance for biomedical applications.