Two types of block copolymers, 38 and 3b, were synthesized from a-hydro-w-(2-hydroxyethylthio)poly[l-(3,3,4,4,5,5,6,6,6-nonafluorohexyloxyc~bony~)ethyIene] (la) or a-hydro-w-(2-aminoethylthio)poly[l -(hexyloxycarbonyl)ethylene] (1 b) and a,w-bis(4-cyanatophenyIthio)poly(1 -phenylethylene) (2), respectively, and the adhesion of blood platelets to these polymer surfaces was evaluated. Adhesion and activation of platelets were found to be effectively suppressed at the lamellar-microdomain surface of block copolymer 38, having a surface free energy gap between microdomains of about 20 dyn/cm, whereas no such a suppression was observed for the microdomain structured surface of block copolymer 3b with a small surface free energy gap between the microdomains. Further, a random copolymer from nonafluorohexyl acrylate and styrene without microdomain structure does not suppress the adhesion and activation of platelets. From these results, it was concluded that the microdomain morphology and the surface free energy gap between microdomains is important to produce antithrombogenicity.

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