Improved adhesion of silicone rubber to polyurethane by surface grafting

Polyurethane (PU) has widespread applications in implantable devices because of its excellent mechanical and biocompatible properties, whereas weak biostability limits its long-term implantation. The introduction of silicone rubber (SR) onto the PU surface is an effective method for improving the biostability of PU, but the adhesion of these two polymers is unsatisfactory. In this study, the surface modification of PU via grafting through the introduction of vinyl and SiH groups onto the PU surface was attempted to improve the adhesion of PU to SR. Fourier transform infrared, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy were employed to investigate the graft reaction on the PU surface. The interfacial and surface morphology was characterized with scanning electron microscopy. Different PU/SR interfaces after oscillation and shear were compared as well. The results indicated that the PU surface was activated by diisocyanate, which generated free isocyanate groups for the further grafting of vinyl and SiH groups. When addition-type, room-temperature-vulcanized SR was poured onto the PU surface, the vinyl and SiH groups on the PU surface underwent an addition reaction, which improved the adhesion of PU and SR by connecting them with chemical bonds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011