Blood compatibility of polyurethane immobilized with acrylic acid and plasma grafting sulfonic acid.

Sulfonic and carboxyl groups can effectively improve the blood compatibility of polyurethane. But it is difficult to obtain an optimum ratio of the two groups. In this article, polyurethane (PU) was dissolved with acrylic acid in a tetrahydrofuran solution and then spread on the glass plate to produce a film. At the same time, acrylic acid partly polymerized and immobilized with the PU films. The films (PU-AA) were exposed to sulfur dioxide plasma to graft sulfonic acid group on its surfaces. Through adjusting the quantity of acrylic acid and the plasma reaction condition, the antithrombin of polyurethane can be improved. The surface-modified PUs were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscope (XPS) and a contact angle goniometer. The blood compatibility of the films was examined by using thrombin time (TT), activated partial thromboplastin time (APTT) and prothrombin time (PT). The TT and APTT were significantly prolonged for the surface-modified films of PU-AA by sulfur dioxide plasma and only APTT was elongated for PU-AA. The results suggest that sulfonic acid and acrylic acid have the different effect on the blood compatibility of surface-modified PUs.