Study On The Surface Modification Of PCU To Improve Its Blood Compatibility By Graft Polymerization

In this paper, surface modification of polycarbonate urethane (PCU) was studiedto improve its hemocompatibility via the graft polymerization of some hydrophilicmonomers. Firstly, via ultraviolet (UV) radiation grafting method andsurface-initiated atom transfer radical polymerization (SI-ATRP),2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted from PCU to obtainzwitterionic and biomimetic surface for improving its blood compatibility. Thedifference of two kinds of graft polymerizations was discussed. Secondly, thecopolymers of poly(ethylene glycol)(PEG) and MPC were synthesized by variousPEG chain lengths via SI-ATRP. The effect of the different copolymers on theproperties of the graft layers was studied. Finally, two copolymers of a MPC-likemonomer,3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate(DMAPS), and poly(ethylene glycol) monoacrylate (PEGMA) were grafted onto PCUto obtain high graft density. The copolymers were synthesized by SI-ATRP, and theeffect of the graft chain structure on surface modification was discussed.The surface-grafted PCU films were measured by fourier transform infraredspectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) to characterize thesurface chemical composition; the hydrophilicity and hemocompatibility of sampleswere studied by water contact angle and platelet adhesion test，respectively. By thephase image of AFM, the relationship between the graft chain structure and the graftlayer topology was studied.The hydrophilicity and hemocompatibility of PCU were improved by themodification. The water contact angle of surface-grafted PCU films becomes lowcompared with the PCU. Platelet adhesion on the surface-grafted PCU films was verylittle, even some samples did not adsorb any platelet. The characteristic of eachmethod was studied in this paper.