Novel Polyisobutylene-Based Polyurethanes for Health Care

Polyurethanes (PUs) consist of hard (high Tg) polymer domains dispersed in soft (low Tg, rubbery) polyester, polyether, polycarbonate, or polysiloxane matrixes whose structures are chemically vulnerable, particularly in contact with body fluids. The Achilles heel of PUs is poor oxidative-hydrolytic-enzymatic stability. Thus the long term implantation of even the highest grade “biostable” PUs as pacemaker lead insulators, cardiac assist devices, heart patches, etc. into living organisms is fraught with danger due to environmental stress cracking and/or metal ion catalyzed oxidative failure. We have designed, developed, and tested PUs with PIB soft segments (PIB-based PUs) exhibiting excellent mechanical properties, processing characteristics, and unparalleled oxidative-hydrolytic-enzymatic stability (resistant to HNO₃ and H₂O₂) far superior to even the best contemporary PUs. We present specifics, and explain the reason(s) for this combination of outstanding properties in terms of chemical composition and molecular architecture.