Surface graft polymerization of poly(ethylene glycol) methacrylate onto polyurethane via thiol-ene reaction: preparation and characterizations.

A new surface modification that facilitates the grafting of poly(ethylene glycol) methacrylate (PEGMA) on a polyurethane (PU) surface was developed using a thiol-ene reaction. The thiolated PU surface for the grafting of PEGMA was created by fabricating allylated PU through an allophanate reaction, which was then modified with tetra-thiols to enhance the functionality of the PU surface. The amount of thiol groups increased with increasing irradiation time, and its concentration was almost equilibrated after 30 min irradiation. ESCA spectra revealed new two peaks on the thiolated PU surface at 163 and 228 eV, which was assigned to sulfur, and a significant increase in the oxygen content of the poly(PEGMA)-grafted PU was shown as compared with the other groups. Also, the irradiation time-dependent increase in the surface wettability of poly(PEGMA)-grafted PU was confirmed by contact angle measurement. These surface characteristics support that poly(PEGMA)-grafted PU was successfully prepared using a thiol-ene reaction. For in vitro protein adsorption and cell proliferation tests, the poly(PEGMA)-grafted PU surface showed repellent properties against both fibrinogen and smooth muscle cells, compared to other groups. This surface graft polymerization of PEGMA on a PU surface via a thiol-ene reaction can be used as a promising surface modification for improving blood compatibility of PU-based blood-contacting devices.