Tanzi M C, Mantovani D, Petrini P, Guidoin R, Laroche G
Dipartimento di Bioingegneria, P.zza L. da Vinci, Milano, Italia.
J Biomed Mater Res. 1997 Sep 15;36(4):550-9. doi: 10.1002/(sici)1097-4636(19970915)36:4<550::aid-jbm14>3.0.co;2-e.
The relative chemical stability of two commercially available polyurethanes-Pellethane, currently used in biomedical devices, and Corethane, considered as a potential biomaterial-was investigated following aging protocols in hydrolytic and oxidative conditions (HOC, water, hydrogen peroxide, and nitric acid) and in physiological media (PHM, phosphate buffer, lipid dispersion, and bile from human donors). The chemical modifications induced on these polymers were characterized using differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and Fourier transform infrared spectroscopy (FTIR). With the exception of nitric acid, all of the aging media promoted a mild hydrolytic reaction leading to a slight molecular weight loss in both polymers. When aged in water and hydrogen peroxide, Pellethane experienced structural modifications through microdomain phase separation along with an increase of the order within the soft-hard segment domains. The incubation of Pellethane in nitric acid also resulted in an important decrease of the melting temperature of its hard segments with chain scission mechanisms. Moreover, incubation in PHM led to an increase of the order within shorter hard-segment domains. FTIR data revealed the presence of aliphatic amide molecules used as additives on the Pellethane's surface. The incubation of Corethane under the same conditions promoted an almost uniform molecular reorganization through a phase separation between the hard and soft segments as well as an increase of the short-range order within the hard-segment domains. Incubation of this polymer in nitric acid also resulted in a chain scission process that was less pronounced than that measured for the Pellethane samples. Finally, lipid adsorption occurred on the Corethane sample incubated in bile for 120 days. Overall data indicate that polycarbonate urethane presents a greater chemical stability than does polyetherurethane.
研究了两种市售聚氨酯——目前用于生物医学设备的聚醚氨酯（Pellethane）和被视为潜在生物材料的聚碳酸酯氨酯（Corethane）——在水解和氧化条件（水解氧化条件，水、过氧化氢和硝酸）以及生理介质（生理介质，磷酸盐缓冲液、脂质分散液和人体捐献者的胆汁）下按照老化方案处理后的相对化学稳定性。使用差示扫描量热法（DSC）、凝胶渗透色谱法（GPC）和傅里叶变换红外光谱法（FTIR）对这些聚合物上诱导的化学修饰进行了表征。除硝酸外，所有老化介质都促进了温和的水解反应，导致两种聚合物的分子量略有损失。当在水和过氧化氢中老化时，聚醚氨酯通过微区相分离经历结构修饰，同时软硬段域内的有序度增加。聚醚氨酯在硝酸中的孵育还导致其硬段的熔融温度因断链机制而显著降低。此外，在生理介质中的孵育导致较短硬段域内的有序度增加。FTIR数据显示聚醚氨酯表面存在用作添加剂的脂肪族酰胺分子。在相同条件下聚碳酸酯氨酯的孵育通过软硬段之间的相分离促进了几乎均匀的分子重组，以及硬段域内短程有序度的增加。该聚合物在硝酸中的孵育也导致了断链过程，但其程度不如聚醚氨酯样品明显。最后，在胆汁中孵育120天的聚碳酸酯氨酯样品上发生了脂质吸附。总体数据表明，聚碳酸酯氨酯比聚醚氨酯具有更高的化学稳定性。
