Prevention of oxidative degradation of polyurethane by covalent attachment of di‐tert‐butylphenol residues

Abstract

Polyurethane (PU) components of cardiovascular devices are subjected to oxidation-initiated surface degradation, which leads to cracking and ultimately device failure. In the present study, we investigated a novel bromoalkylation chemical strategy to covalently attach the antioxidant, di-tert-butylphenol (DBP), and/or cholesterol (Chol) to the PU urethane nitrogen groups to hypothetically prevent oxidative degradation. These experiments compared PU, PU-DBP, PU-Chol, and PU-Chol-DBP. A series of comparative oxidative degradation studies involved exposing PU samples (modified and unmodified) to H2O2-CoCl2 for 15 days at 37 degrees C, to cause accelerated oxidative degradation. The extent and effects of degradation were assessed by attenuated total reflectance Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM), surface contact angle measurements, and mechanical testing. Both the Chol and DBP modification conferred significant resistance to oxidation related changes compared to unmodified PU per FTIR and SEM results. SEM demonstrated cavitation only in unmodified PU. However, contact angle analysis showed significant oxidation-induced changes only in the Chol-modified PU formulations. Most importantly, uniaxial stress-strain testing revealed that only PU-DBP demonstrated bulk elastomeric properties that were minimally affected by oxidation; PU, PU-Chol, PU-Chol-DBP showed marked deterioration of their stress-strain properties following oxidation. In conclusion, these results demonstrate that derivatizing PU with DBP confers significant resistance to oxidative degradation compared with unmodified PU.

The effect of CD47 modified polymer surfaces on inflammatory cell attachment and activation

“…PU or PVC was dissolved in dimethylacetamide and tetrahyrdofuran respectively, and then solvent cast as films with thickness ranging between 159 and 220 μm as used in prior studies [14, 15]. Films, both PU and PVC, were then cut into appropriate sizes for in vitro and in vivo analysis.…”

“…All spectra were obtained under identical conditions from 200 scans collected at a resolution of 2 cm −1 , at a 45° angle of incidence and the atmospheric water vapor and carbon dioxide were accounted for by subtracting the appropriate reference spectrum using the Omnic software package. Deconvoluted peak measurements were acquired for the 1174 cm −1 peak and normalized to the measured 1590 cm −1 peak heights [14, 18, 19]. …”

Overview on Biocompatibilities of Implantable Biomaterials

“…While the mechanisms of these forms of degradation are not fully understood, an awareness of their causes and effects that leads to all of the long-term functionality is required for the sophisticated PU-based devices of today and tomorrow [190][191]. Over the last half century, extremely efforts have been paid in the biomedical research field to improve the biocompatibilities and biodurability of the PU implants, but only resulted in very little clinical effects [192][193][194].…”

Biocompatibility and Biological Performance of the Improved Polyurethane Membranes for Medical Applications

“…Adding antioxidant compounds to materials can improve their resistance against tissue degradation (Oral et. al., 2006;Stachelek et. al., 2006;Wattamwar et.…”