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Dithiothreitol-based polyurethanes. Synthesis and degradation studies

机译：二硫苏糖醇基聚氨酯。合成与降解研究

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摘要

The synthesis, characterization, and some properties of new copolyurethanes are described. These copolyurethanes were obtained by reaction of 1,4-di-S-benzyl-D,L-dithiothreitol (DTTSBn) and triethylene glycol (TEG) with 1,6-hexamethylene diisocyanate (HMDI). The copolymer compositions were studied by ~1H NMR, revealing that the content of the copolymer units is in good agreement with that of their corresponding feed. The PU(TEG-HMDI) homopolymer exhibited a high crystallinity, but the introduction of the DTTSBn diol led to a reduction in the crystallinity of the copolymers and an increase of the stiffness, with associated increases in the T_g values. In their TG curves, the copolymers exhibited a mixed trend of the related homopolymers; all of them were thermally stable, with degradation temperatures above 250 ℃ and with higher thermal resistance displayed by the polymers with higher TEG contents. The chemical and enzymatically catalyzed hydrolytic degradations of the macromolecules were tested. PU(TEG-HMDI) was the only polymer degraded under physiological conditions, but an increase of temperature markedly affected the degradation rates. Two proteolytic enzymes (papain and α-chymo-trypsin) and two esterase enzymes (cholesterol esterase and lipase) were chosen to perform enzyme-mediated hydrolysis trials, the first reported use of pancreatic lipase for urethane-bond hydrolysis in polyurethanes.
机译：描述了新型共聚聚氨酯的合成，表征和一些性能。这些共聚聚氨酯是通过1,4-二-S-苄基-D，L-二硫苏糖醇（DTTSBn）和三乙二醇（TEG）与1,6-六亚甲基二异氰酸酯（HMDI）反应获得的。通过〜1 H NMR研究了共聚物的组成，发现共聚物单元的含量与其相应进料的含量很好地吻合。 PU（TEG-HMDI）均聚物显示出高结晶度，但是DTTSBn二醇的引入导致共聚物的结晶度降低和刚度增加，并伴随着T_g值的增加。在它们的TG曲线中，共聚物表现出相关均聚物的混合趋势。它们均具有热稳定性，降解温度高于250℃，并且具有较高TEG含量的聚合物显示出较高的耐热性。测试了大分子的化学和酶催化水解降解。 PU（TEG-HMDI）是在生理条件下降解的唯一聚合物，但温度升高明显影响降解速率。选择了两种蛋白水解酶（木瓜蛋白酶和α-胰凝乳蛋白酶）和两种酯酶（胆固醇酯酶和脂肪酶）进行酶介导的水解试验，首次报道了使用胰腺脂肪酶在聚氨酯中进行聚氨酯键水解。

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