title: Degradation of polyetherurethane by subcutaneous implantation into rats. II. Changes of contact angles, infrared spectra, and nuclear magnetic resonance spectra.
abstract: In vivo degradation of polyetherurethanes (PEUs) was studied using two kinds of PEUs, U-3 and U-8, coated on a base film of ethylene/vinyl alcohol copolymer (EVAL). U-3 is a nonsegmented PEU prepared from 4,4'-diisocyanatodiphenylmethane (MDI) and poly(tetramethylene oxide) (PTMO 1000). U-8 is a segmented PEU prepared from MDI, PTMO 1000, and 1,4-butanediol. Previous studies of PEUs were conducted using gel permeation chromatography and scanning electron microscopy. In this study, the explanted materials were examined with contact angle measurement, ATR-FTIR, and nuclear magnetic resonance (NMR) spectroscopies. All data obtained by these methodologies indicate that the PTMO/MDI oligomers diffused to the material surface in the early stage of implantation. Then, the low-molecular-weight fraction of the oligomers leached out from the surface to the exudate. Degradation became dominant after 2-4 weeks. In the case of PU-8, the PTMO fraction decreased approximately 35-40% from the surface at 24 weeks postimplantation. In the case of PU-3, the loss of coating material (U-3) on the base film (EVAL) was observed after 10 weeks. The PTMO fraction of the surface U-3 remained on EVAL at 6 weeks postimplantation, however, it was 64% of the initial material. The molecular weight of the U-3 remaining on EVAL also decreased. Degradation of U-3 occurred more rapidly than that of U-8. The data obtained with our materials were insufficient in determining evidence of oxidative degradation with IR or NMR spectra.
authors.affiliation: National Institute of Health Sciences, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Sato
authors.forename: T
authors.initials: T
authors.lastname: Xi
authors.forename: A
authors.initials: A
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Kawasaki
authors.forename: T
authors.initials: T
authors.lastname: Umemura
authors.forename: M
authors.initials: M
authors.lastname: Tsuda
authors.forename: Y
authors.initials: Y
authors.lastname: Kurokawa
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002850:Chromatography, Gel; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D010084:Oxidation-Reduction; D011140:Polyurethanes / Q000737:chemistry / Q000378:metabolism*; D019736:Prostheses and Implants; D051381:Rats; D012879:Skin Physiological Phenomena; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D011140:Polyurethanes; C115016:polyetherurethane