Abstract: The surface properties of polysiloxane-polyurea block copolymers (PUSE) and polysiloxane-polyurethane (PUSM) zwitterionomers have been investigated by ESCA and analysis of surface contact angle. It was found that the soft segment of polysiloxane richened on the surface of PUSE and PUSM. The increase of phase segregation would be advantageous to the further richness of polysiloxane on the surface. However, in the surface layer of about 50 Athere was still a certain proportion of hard segment and the surface layer remained a heterogeneous structure. In the case of PUSE, as the proportion of both bulk and surface hard segment increased, the contact angle and the time of forming thrombus linearly decreased. In PUSM because of an increase of zwitterions, the contact "angle was reduced and time of forming thrombus was shortened.

Key words: Polysiloxane-polyurea block copolymer, Polysiloxane-polyurethane zwitterionomer, Surface property