Aliphatic polyesters based on long-chain monomers were synthesized for the first time almost a century ago. In fact, Carothers’ seminal observations that founded the entire field of synthetic polymer fibers were made on such a polyester sample. However, as materials, they have evolved only over the past decade. This is driven by the corresponding monomers becoming practically available from advanced catalytic conversions of plant oils, and future prospects comprise a possible generation from third-generation feedstocks, such as microalgae or waste. Long-chain polyesters such as polyester-18.18 can be considered to be polyethylene chains with a low density of potential breakpoints in the chain. These do not compromise the crystalline structure or the material properties, which resemble linear high-density polyethylene (HDPE), and the materials can also be melt processed by injection molding, film or fiber extrusion, and filament deposition in additive manufacturing. At the same time, they enable closed-loop chemical recycling via solvolysis, which is also possible in mixed waste streams containing polyolefins and even poly(ethylene terephthalate). Recovered monomers possess a quality that enables the generation of recycled polyesters with properties on par with those of the virgin material. The (bio)degradability varies enormously with the constituent monomers. Polyesters based on short-chain diols and long-chain dicarboxylates fully mineralize under industrial composting conditions, despite their HDPE-like crystallinity and hydrophobicity. Fundamental studies of the morphology and thermal behavior of these polymers revealed the location of the in-chain groups and their peculiar role in structure formation during crystallization as well as during melting. All of the concepts outlined were extended to, and elaborated on further, by analogous long-chain aliphatic polymers with other in-chain groups such as carbonates and acetals. The title materials are a potential solution for much needed circular closed-loop recyclable plastics that also as a backstop if lost to the environment will not be persistent for many decades.

中文翻译：

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闭环可回收非持久性类聚乙烯聚酯

大约一个世纪前，首次合成了基于长链单体的脂肪族聚酯。事实上，卡罗瑟斯开创整个合成聚合物纤维领域的开创性观察就是在这样的聚酯样品上进行的。然而，作为材料，它们仅在过去十年中才得到发展。这是由植物油的先进催化转化中实际可用的相应单体推动的，未来的前景包括可能从第三代原料（例如微藻或废物）中产生。长链聚酯如聚酯18.18可被认为是链中潜在断点密度低的聚乙烯链。这些不会损害晶体结构或材料特性，类似于线性高密度聚乙烯 (HDPE)，并且这些材料还可以通过注塑成型、薄膜或纤维挤出以及增材制造中的长丝沉积进行熔融加工。同时，它们还可以通过溶剂分解实现闭环化学回收，这在含有聚烯烃甚至聚对苯二甲酸乙二醇酯的混合废物流中也是可能的。回收的单体具有能够生成具有与原始材料相同性能的回收聚酯的品质。 （生物）降解性随组成单体的不同而变化很大。基于短链二醇和长链二羧酸酯的聚酯尽管具有类似 HDPE 的结晶度和疏水性，但在工业堆肥条件下可完全矿化。这些聚合物的形态和热行为的基础研究揭示了链内基团的位置及其在结晶和熔融过程中结构形成中的特殊作用。所有概述的概念都被扩展到具有其他链内基团（例如碳酸酯和缩醛）的类似长链脂肪族聚合物，并得到进一步阐述。标题材料是急需的圆形闭环可回收塑料的潜在解决方案，如果丢失到环境中，也可以作为后盾，但不会持续数十年。