title: Long term in vitro biostability of segmented polyisobutylene-based thermoplastic polyurethanes.
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 0.1M 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.
authors: Department of Chemistry, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA.
authors: David
authors: D
authors: Cozzens
authors: Umaprasana
authors: U
authors: Ojha
authors: Pallavi
authors: P
authors: Kulkarni
authors: Rudolf
authors: R
authors: Faust
authors: Shrojal
authors: S
authors: Desai
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D003035:Cobalt / Q000737:chemistry / Q000378:metabolism; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D011090:Polyenes / Q000737:chemistry / Q000378:metabolism; D011108:Polymers / Q000737:chemistry / Q000378:metabolism; D011140:Polyurethanes / Q000737:chemistry / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D011090:Polyenes; D011108:Polymers; D011140:Polyurethanes; C059617:pellethane 2363-55D; D003035:Cobalt; C008967:polyisobutylene; C018021:cobaltous chloride