TPU with outstanding wettability and hydrophilic stability is obtained by plasma-induced graft polymerization

Hydrophilic thermoplastic polyurethane (TPU) is applicable in the fields of packaging, oil–water separation, and biomedical. Nevertheless, the process of its preparation is still a great challenge. The objective of this study is to develop TPU with excellent wettability and hydrophilic stability by surface modification. Four methods were evaluated: coating with PVP (polyvinylpyrrolidone) solution, immersion in PVP solution, N2/Ar plasma treatment, and N2/Ar plasma-induced graft polymerization with PVP. Finally, the results indicate that the sample called TPU-g-PVP, which utilizes plasma-induced grafting, exhibits the best performance. The water contact angle (WCA) reduces from 109° to 9.2°, and maintains within 20° after 80 days under atmospheric conditions. Its surface energy (72.4 mN/m) is increased by 2.8 times than untreated TPU. The surface morphology and roughness are almost unchanged when compared to the original TPU when compared to the original TPU. Some characteristic peaks (–OH and C = O) of PVP on the TPU-g-PVP were found by infrared spectroscopy. X-ray photoelectron spectroscopy (XPS) examination revealed a reduction in C on the TPU surface as the quantity of N and O increases. Experiments on biocompatibility showed that the PVP deposited substrates improved cell adherence without generating new cytotoxicity.