In vitro oxidative stability of high strength siloxane poly(urethane-urea) elastomers based on linked-macrodiol

In vitro oxidative stability of two siloxane poly(urethane urea)s synthesized using 4,4 '-methylenediphenyl diisocyanate (in SiPUU-1) and Isophorone diisocyanate (in SiPUU-2) linked soft segment was evaluated using 20% H2O2 and 0.1 mol/L CoCl2 solution at 37 degrees C under 150% strain. Commercially available siloxane polyurethane (Elast-Eon (TM) 2A) and polyether polyurethane (ChronoThane P (TM) 80A) were used as negative and positive controls, respectively. ChronoSil (TM) 80A was included as another commercially available polycarbonate polyurethane. Scanning electron microscopic (SEM) examinations, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and molecular weight reduction revealed the extensive degradation of ChronoThane P (TM) 80A after 90 days while SiPUU-1, SiPUU-2 and Elast-Eon (TM) 2A showed no noticeable surface degradation. ChronoSil (TM) 80A showed degradation in both soft and hard segments. Tensile testing was carried out only on unstrained polyurethanes for 90 days. ChronoThane P (TM) 80A showed 35% loss in ultimate tensile strength and it was only 13-14% for SiPUU-1 and Elast-Eon (TM) 2A. However, the tensile strength of ChronoSil (TM) 80A was not significantly affected. The results of this study proved that SiPUU-1 possess oxidative stability comparable with Elast-Eon (TM) 2A. (c) 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2557-2565, 2019.