THERMOPLASTIC SILOXANE-URETHANE COPOLYMER DEVELOPMENT

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This project would test the hypothesis that biostability of thermoplastic polyurethanes (TPU) can be improved by replacing all or part of the polyether soft segment with telechelic polydimethylsiloxane (PSX) oligomer during synthesis. This approach is based on the reported improvement in-vivo stability of solvent-cast polyurethanes through the admixture or grafting of reactive PSX into/onto urethane vased polymers and the known in-vivo stability of PSX. In Phase I the subcutaneous in-vivo stability of several different polyurethane will be determined. Aromatic TPUs from PSX, polytetramethyleneoxide and polyethyleneoxide and several PSX/polyether terpolymer polyurethane films will be characterized after explantation by bulk and surface analytical methods capable of detecting molecular weight reduction and changes in surface chemistry and morphology associated with the degradation process. Positive phase I results will be utilized in Phase II to complete the development and commercialization of a family of biomedical PSX-TPUs. These materials will be suitable for solvent casting, extrusion and injection molding. They will combine the biodegradation resistance and desirable surface properties of PSX, with the processing ease and wide range of bulk properties available in conventional TPUs.