Surface-initiated reverse atom transfer radical polymerization (SI-RATRP) for blood-compatible polyurethane substrates

A well-defined polymer brushes (2-(methacryloyloxy) ethyl phosphorylcholine, MPC) grafted from the polyurethane (PU) substrate by surface-initiated reverse atom transfer radical polymerization (SI-RATRP) was studied. In this work, a kind of silane coupling agent (3-chloropropyltrimethoxysilane, CPTM) was adopted to serve as a coupling agent as well as a ligand for the first time. Surface structure, wettability, morphology of the PU substrates before and after modification were characterized by Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy measurement (XPS), Atomic force microscope (AFM), Water contact angle measurement, respectively. The results showed that zwitterionic brushes were successfully fabricated on the PU surfaces, and the content of the grafted layer increased gradually with the polymerization time. The blood compatibility of the PU substrates was evaluated by protein adsorption tests and platelet adhesion tests in vitro. It was found that all the PU functionalized with zwitterionic brush showed improved resistance to nonspecific protein adsorption and platelet adhesion.