¹H-NMR spectroscopic study of the effect of aging vascular prostheses made of poly(ethylene terephthalate) on the macromolecular weight

Trichloroacetyl isocyanate reacts rapidly and quantitatively with both acid and hydroxyl chain ends to form derivatives that can be readily determined by ¹H-NMR spectroscopy. This method provides a convenient mean for characterization of polyethylene terephthalate (PET) end-groups. The ¹H-NMR spectroscopy has been applied to describe the chemical aging of the PET vascular prostheses by determination of the hydroxyl and carboxyl end-group concentrations and therefore the macromolecular weight. To validate ¹H-NMR results, we used chemical titration of the end-groups and classical viscosimetric method as complementary techniques. The analyses made on the explants of different lifetime demonstrated a significant deterioration compared with the virgin prostheses. A high degradation of macromolecular weight is observed. This phenomenon is explained by a random scission of the ester linkages.