Recovering monomers from the depolymerization of thermosets presents a significant challenge, which becomes even more daunting if one sets the goal of doing it directly, i.e., without complex chemical separation steps. To this end, we have synthesized a new type of polycarbonate thermoset by first copolymerizing alkyl cyclic carbonates (ACCs) with small amounts of allyloxy cyclic carbonates (AoCCs), followed by cross-linking the resulting allyloxy polycarbonate with excess tetrathiol compounds under UV irradiation. These cross-linked polycarbonates demonstrate enhanced thermal and mechanical properties compared to their linear analogues, while maintaining the linear polymers’ capacity for ring-closing depolymerization. The depolymerization process enables the direct recovery of ACC and its dimer, bypassing complex chemical separation steps that are commonly employed in the recycling of conventional chemically recyclable thermosets. The yields range from 74.7% to 91.7% depending on the ratios of AoCC to ACC in the thermosets. Furthermore, the recovered compounds can be repolymerized with AoCCs leading to polycarbonate of the same quality to the initially synthesized one.

中文翻译：

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从热固性塑料的闭环解聚中直接回收单体


从热固性塑料解聚中回收单体是一项重大挑战，如果设定直接进行的目标，即无需复杂的化学分离步骤，这将变得更加艰巨。为此，我们首先将烷基环状碳酸酯 （ACC） 与少量烯丙氧基环状碳酸酯 （AoCC） 共聚，然后在紫外线照射下将所得烯丙基碳酸盐与过量的四硫醇化合物交联，从而合成了一种新型的聚碳酸酯热固性。与线性类似物相比，这些交联聚碳酸酯表现出更强的热性能和机械性能，同时保持线性聚合物的闭环解聚能力。解聚工艺能够直接回收 ACC 及其二聚体，绕过了传统化学可回收热固性塑料回收中常用的复杂化学分离步骤。收率从 74.7% 到 91.7% 不等，具体取决于热固性塑料中 AoCC 与 ACC 的比例。此外，回收的化合物可以用 AoCC再聚合，从而得到与最初合成的聚碳酸酯质量相同的聚碳酸酯。