Effect of microstructure of poly(propylene-oxide)-segmented polyamides on platelet adhesion

The relationship between microstructure and platelet adhesivity of six types of poly(propylene oxide) (PPO)-segmented polyamides based on the polyamide segments nylon 210, 310, 410, 510, 610, and 710 were investigated. These multiblock PPO-segmented copolymers were prepared by interfacial polycondensation. Physical characterization of these copolymers was by means of thermal analysis, transmission electron microscope, wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). The WAXD and SAXS measurements showed that the copolymers had microstructures containing crystalline and amorphous phases and that these microstructures, represented by means of crystallite thickness and long period, varied with incorporation of PPO segments. Blood compatibility of these copolymers was evaluated by estimating the amount of adhering platelets on the copolymer surfaces. The amount of adhering platelets was minimum for the surfaces of the copolymers having a crystallite thickness of 6.0-6.5 nm and a long period of 12-13 nm. This result suggests that the particular size and distribution of the crystalline and amorphous phases in the copolymer could be determining factors for suppressing platelet adhesion on the copolymer surface, and that the control of these factors could lead to ideal antithrombogenic polymers.