The structural evolution of poly(ethylene terephthalate) oligomers produced via glycolysis depolymerization
The structural evolution of poly(ethylene terephthalate) oligomers produced via glycolysis depolymerization
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通过糖酵解解聚产生的聚对苯二甲酸乙二醇酯低聚物的结构演变
DOI：
10.1039/d2ta07467b
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发表时间：
2023
影响因子：
11.9
通讯作者：
Dadmun, Mark D.
中科院分区：
文献类型：
--
作者：
Moncada, Joshua;Dadmun, Mark D.
聚合物材料已成为我们社会不可或缺的一部分，其高需求导致大量聚合物最终进入废物流。例如，聚（对苯二甲酸乙二醇酯）（PET）广泛用于广泛的应用中，其中PET的化学回收越来越受到关注。大多数方法集中在PET完全解聚成单体，然而将平衡反应推到单体是时间和能量密集的。我们假设通过在解聚中截取中间体，可以捕获遥爪低聚物，其也可以用作反应物以产生增值产品。为此，研究了反应类型、催化剂用量、反应时间和温度对PET糖酵解解聚产物链结构和产率的影响。对于在较低温度（165 °C）下的非均相反应，解聚速率足够慢以提供以高产率（接近100%）获得宽范围的分子量产物（3000-10 000道尔顿）。 在较高的非均相反应温度（175和185 °C）下，反应速率增加，产生较窄分子量范围（2000-5000道尔顿）的低聚物，其中原始PET的显著损失高达40%，作为水溶性产物。在非均相反应中，当在较高温度下改变催化剂负载量时观察到很少变化，但较低温度和降低的催化剂负载量产生可获得的较高分子量低聚物。糖酵解反应的均相催化增加解聚速率，使得难以分离Mn > 1000道尔顿的低聚物。将来自非均相反应的低聚物用作反应物以与乙二醇形成嵌段共聚物，举例说明它们在增值材料的生产中作为前体的用途。因此，这些实验提供了关键的洞察如何反应条件可以很容易地调整，以产生目标遥爪低聚物的PET。
Polymeric materials have become an integral part of our society, and their high demand has created a large quantity of polymers that end up in the waste stream. For instance, poly(ethylene terephthalate) (PET) is widely used in a broad range of applications, where the chemical recycling of PET is of growing interest. Most methods focus on the complete depolymerization of PET to the monomer, however pushing the equilibrium reaction to the monomer is time- and energy-intensive. We hypothesize that by intercepting intermediates in the depolymerization, telechelic oligomers can be captured that can also be used as reactants to produce value-added goods. To this end, the effect of reaction type, catalyst loading, reaction time, and temperature on the evolution of the product chain structure and yield of the glycolysis depolymerization of PET is studied. For a heterogeneous reaction at lower temperatures (165 °C), the rate of depolymerization is sufficiently slow to offer access to a broad range of molecular weight products (3000–10 000 Daltons) at a high yield (nearly 100%). At higher heterogeneous reaction temperatures (175 and 185 °C), the reaction rate increases, producing oligomers of a narrower molecular weight range (2000–5000 Daltons) with significant loss of the original PET, up to 40%, as water soluble products. In the heterogeneous reaction, little change was observed when altering the catalyst loading at higher temperatures, but lower temperatures and decreased catalyst loading produce accessible higher molecular weight oligomers. Homogeneous catalysis of the glycolysis reactions increases the rate of depolymerization, such that it is difficult to isolate oligomers with Mn > 1000 Daltons. The oligomers from heterogeneous reactions were used as reactants to form block copolymers with ethylene glycol, exemplifying their use as precursors in the production of value-added materials. These experiments, therefore, offer crucial insight into how reaction conditions can be readily tuned to produce target telechelic oligomers of PET.
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