Polyurethane with long hard segment for self-healing in blood environment around body temperature

Intravascular medical devices, like catheter, not only need to fulfill the challenge of biocompatibility but also be resistant to cracking or even breakage due to blood flushing and corrosion. Here, we synthesized polyurethanes with long hard segment for higher mechanical strength and effective self-healing in blood. In detail, Bis(trifluoromethyl)benzidine (TFMB) and dynamically linked 4-Aminophenyl disulfide (APS), and mixed diisocyanates of diisothiocyanate (PDITC) and hexamethylene diisocyanate (HMDI) were chosen to construct the long hard segment, which possesses hydrophobicity, dynamical bonds and a super strong hydrogen bonding interaction. For a selected sample, PU-4, which benefited from multi-hydrogen bonding, the degree of hydrogen bonding association kept as high as ∼ 97 % from 30 to 70 °C, and rheological testing proved that the hard domain and physical network are still stable at ∼ 115 °C. On the other hand, the surface content of Si is as high as 40 wt%, which not only endows the polymer with hydrophobicity but also a bioinert and antithrombotic surface. Consequently, the PU-4 showed a hemolysis rate of 0.4 %, an activated partial thromboplastin time of 50 s and free of platelet adhesion. By successfully screening complicate protein and ionic interactions with polymer chains, the self-healing of PU-4 in blood at 35 °C was realized, with mechanical strength recoverability up to 82 %.