Long term in vitro biostability of segmented polyisobutylene-based thermoplastic polyurethanes

✍ Scribed by David Cozzens; Umaprasana Ojha; Pallavi Kulkarni; Rudolf Faust; Shrojal Desai

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 739 KB
• Volume: 95A
• Category: Article
• ISSN: 1549-3296
• DOI: 10.1002/jbm.a.32897

✦ Synopsis

Abstract

Long term in vitro biostability of thermoplastic polyurethanes (TPUs) containing mixed polyisobutylene (PIB)/poly(tetramethylene oxide) (PTMO) soft segment was studied under accelerated conditions in 20% H~2~O~2~ solution containing 0.1__M__ CoCl~2~ at 50°C to predict resistance to metal ion oxidative degradation (MIO) in vivo. The PIB‐based TPUs showed significant oxidative stability as compared to the commercial controls Pellethane™ 2363‐55D and 2363‐80A. After 12 weeks in vitro the PIB‐PTMO TPUs with 10–20% PTMO in the soft segment showed 6–10% weight loss whereas the Pellethane™ TPUs degraded completely in about 9 weeks. Attenuated total reflectance Fourier transform infrared spectroscopy confirmed the degradation of Pellethane™ samples via MIO by the loss of the ∼1110 cm^−1^ aliphatic COC stretching peak height attributed to chain scission, and the appearance of a new peak at ∼1174 cm^−1^ attributed to crosslinking. No such changes were apparent in the spectra of the PIB‐based TPUs. The PIB‐based TPUs exhibited 10–30% drop in tensile strength compared to 100% for the Pellethane™ TPUs after 12 weeks. The molecular weight of the PIB‐based TPUs decreased slightly (10–15%) at 12 weeks. The Pellethane™ TPUs showed a dramatic decrease in M~n~ and an increase in low molecular weight degradation product. Scanning electron microscopy (SEM) showed severe cracking in the Pellethane™ samples after 2 weeks, whereas the PIB‐based TPUs exhibited a continuous surface morphology. The weight loss, tensile, and SEM data correlate well with each other and indicate excellent biostability of these materials. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.