Microporous segmented polyetherurethane vascular graft: I. Dependency of graft morphology and mechanical properties on compositions and fabrication conditions.

The influence of polyurethane compositions and fabrication conditions on the pore morphology and mechanical properties of microporous segmented polyetherurethane (SPEU) grafts, which were produced by the coagulation technique, were carefully investigated in this article. SPEU resins based on polytetramethylene oxide (PTMO) were synthesized by the solution polymerization method. Different types of coagulant were adapted to examine the feasibility of producing a microporous SPEU graft with good structural regularity. The experimental results indicate that a microporous SPEU graft with a uniform pore structure can be fabricated quite conveniently by using a proper concentration of water and ethanol mixed coagulant. Tensile tests demonstrated that the fabricated microporous SPEU grafts possess high mechanical strengths and satisfy the requirements as vessel replacements. The burst strength test also revealed that the SPEU graft can sustain extremely high internal pressure. Furthermore, a high compliant SPEU (high porosity) graft can be obtained by blending a proper amount of "soluble filler" (i.e., free PTMO polyol in this study) into the SPEU resin.

Studies on segmented polyetherurethane for biomedical application: effects of composition and hard-segment content on biocompatibility.

Segmented polyetherurethane (SPEU) materials based on polytetramethylene oxide (PTMO, Mw 1000 and 2000) with various hard-segment contents were synthesized and their biocompatibilities studied via different tests. The static contact angle data reveal that the higher hard-segment-content SPEU material possesses a lower contact angle, implying that the surface of the higher hard-segment-content SPEU is more hydrophilic than its low hard-segment-content SPEU counterpart. The catalyst- and additive-free PTMO-based SPEU materials in this study possess neither a hemolytic nor a cytotoxic response that could be considered non toxic for biomedical applications. By using L-929 cell lines, a cell-seeding test indicated that the higher hard-segment-content SPEU material possesses quicker cell attachment and proliferation behaviors. In vitro platelet adhesion tests indicated that the lower hard-segment-content SPEU possesses less platelet adhesion than the high hard-segment-content SPEU material. Both ex vivo canine artery-artery (A-A) and arterio-venous (A-V) shunting tests revealed that the extent of platelet adhesion reaction is less for lower hard-segment content SPEU. In addition, the blood compatibility of SPEU material synthesized from PTMO 1000 excels over PTMO 2000 SPEU material by near the same levels as the hard-segment-content SPEU.