PDF(Pubmed)
Abstract：
A sudden increase in polyurethane (PU) production necessitates viable recycling methods for the waste generated. PU is one of the most important plastic materials with a wide range of applications; however, the stability of the urethane linkage is a major issue in chemical recycling. In this work, termination reactions of a model urethane molecule, namely methyl N-phenyl carbamate (MPCate), are investigated using G3MP2B3 composite quantum chemical method. Our main goal was to gain insights into the energetic profile of urethane bond termination and find an applicable chemical recycling method. Hydrogenation, hydrolysis, methanolysis, peroxidation, glycolysis, ammonolysis, reduction with methylamine and termination by dimethyl phosphite were explored in both gas and condensed phases. Out of these chemicals, degradation by H2, H2O2 and CH3NH2 revealed promising results with lower activation barriers and exergonic pathways, especially in water solvation. Implementing these effective PU recycling methods can also have significant economic benefits since the obtained products from the reactions are industrially relevant substances. For example, aniline and dimethyl carbonate could be reusable in polymer technologies serving as potential methods for circular economy. As further potential transformations, several ionizations of MPCate were also examined including electron capture and detachment, protonation/deprotonation and reaction with OH-. Alkaline digestion against the model urethane MPCate was found to be promising due to the relatively low activation energy. In an ideal case, the transformation of the urethane bond could be an enzymatic process; therefore, potential enzymes, such as lipoxygenase, were also considered for the catalysis of peroxidation, and lipases for methanolysis.
摘要：
聚氨酯（PU）产量的突然增加需要可行的废物回收方法。PU是最重要的塑料材料之一，具有广泛的应用；然而，氨基甲酸酯键的稳定性是化学回收中的一个主要问题。在这项工作中,模型氨基甲酸酯分子的终止反应，即N-苯基氨基甲酸甲酯（MPCate），用G3MP2B3复合量子化学方法进行了研究。我们的主要目标是深入了解氨基甲酸酯键终止的活力，并找到一种适用的化学回收方法。加氢,水解，甲醇分解，过氧化,糖酵解,氨解,在气相和冷凝相中都探索了用甲胺还原和用亚磷酸二甲酯终止的方法。在这些化学物质中，H2，H2O2和CH3NH2的降解显示出有希望的结果，具有较低的活化屏障和exragonic途径，特别是在水溶性中。实施这些有效的PU再循环方法还可以具有显著的经济效益,因为从反应获得的产物是工业上相关的物质。例如,苯胺和碳酸二甲酯可以在聚合物技术中重复使用，作为循环经济的潜在方法。随着进一步的潜在转变，还检查了MPCate的几种电离，包括电子捕获和分离，质子化/去质子化和与OH-反应。由于活化能相对较低，因此发现对氨基甲酸乙酯MPCate模型的碱性消化是有希望的。在理想情况下,氨基甲酸酯键的转化可能是一个酶促过程；因此，潜在的酶，如脂加氧酶，也被认为是过氧化的催化作用，和用于甲醇分解的脂肪酶。
