Atmospheric DBD-induced grafting for durable hydrophilic modification of inner wall of TPU catheters

Durable hydrophilization of thermoplastic polyurethane (TPU) catheter lumens is limited by hydrophobic recovery and geometric confinement. This study proposes an atmospheric-pressure dielectric barrier discharge (DBD)-assisted plasma grafting strategy to immobilize polyvinylpyrrolidone (PVP K30) onto the inner surface of TPU catheters. Plasma activation generates reactive sites and controlled micro-roughening, enabling subsequent covalent grafting under mild thermal conditions. The water contact angle decreased from 101.33° to 9.91° and remained below 20° over 100 days. The modified layer exhibited high axial and circumferential uniformity and remained stable upon ultrasonication, with consistent values observed across catheters of different diameters. After 30 min of ultrasonic treatment, the water contact angle changed by less than 10°. Spectroscopic and morphological analyses corroborated PVP incorporation and surface-limited restructuring. Mechanistically, the results indicate that long-term hydrophilicity is governed by interfacial chain immobilization rather than transient plasma oxidation. This work provides an organic-solvent-free, vacuum-independent route for durable lumen hydrophilization of polymer catheters.