A novel polyolefin, poly(styrene-b-isobutylene-b-styrene) (Quatromer), is being proposed as a viable polymer for use in trileaflet heart valves because of its oxidative stability. The current study was designed to assess the polymer's hemocompatibility and mechanical durability. Mechanical characterization included static tensile tests and dynamic tension-tension and bending fatigue tests, where the properties of isotropic and composite (polypropylene (PP) embedded) Quatromer specimens were compared with those of a polyurethane (PUR) approved for cardiovascular applications. It was found that by embedding PP fibers into the Quatromer matrix, the tensile and fatigue properties of the polymer could be improved, making them comparable, if not better than the PUR. The thrombotic potential of Quatromer was compared with the PUR, glutaraldehyde-fixed porcine valve material, and a positive and negative control by measuring platelet deposition with radiolabeled platelets in a parallel plate flow configuration. The porcine valve material was found to have significantly higher platelet deposition under all flow regimes, while no significant difference existed between Quatromer and PUR. In conclusion, Quatromer is shown to have suitable hemocompatibility and mechanical durability for use in polymer trileaflet heart valves, and fiber reinforcement can effectively be used to tailor the mechanical properties.

DEDICATIONI dedicate this thesis to my Family and to Maria. Their love and support has been crucial in order for me to complete this work.iii ACKNOWLEDGMENTS Two and a half years ago I knocked on Dr. Schoephoerster's door. I told him I wanted to work towards a master's degree under his supervision. He told me he had nothing available at the time. Four more visits after that he had something for me. Dr.Schoephoerster, thank you for giving me a chance and believing in me.Maria Marquine, thank you for your love, hope, and understanding. Your help with the document was very important.Mariana Oliva, thank you for your long hours of work making the specimens for my tests.Siobhain Gallocher, thank you for always being there for me.Dr. Vladimir Kasyanov, I really enjoyed working with you. Thank you for your support.Dr. James Byrne, your help in the lab was very valuable.Valve Team, thank you for creating such an enjoyable work environment.Dr. Moore and Dr. Agarwal, thank you for your guidance and advice.Dr. Wu and his team, thank you for your help and patience. both its static and dynamic properties as compared to the PU. Hence, this composite has the potential to be a more suitable material for synthetic tri-leaflet heart valves.

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