德国康斯坦茨大学Stefan Mecking研究团队开发了聚乙烯类材料的闭环回收新方法。相关研究成果于2021年2月17日发表在国际知名学术期刊《自然》。

塑料是当今几乎所有技术的关键组成部分。尽管塑料的生产消耗了大量的原料资源，但塑料在使用寿命结束后大部分被处理掉。就循环经济而言，消费后分类聚合物的再利用（“机械回收”）受到材料性能恶化的阻碍。通过解聚到单体的化学回收提供了一种保留高性能特性的替代方法。聚乙烯的线性烃链可实现结晶填充，并提供优异的材料性能。然而，它们的惰性阻碍了化学回收，需要600摄氏度以上的温度，回收乙烯的产率不到10%。

研究表明，可再生的聚碳酸酯和聚酯具有作为聚乙烯链断点的低密度链内官能团，可以通过溶剂分解进行化学回收，回收率超过96%。同时，断裂点不会干扰结晶聚乙烯结构，并且在再循环时完全保留所需的材料性能（如高密度聚乙烯的性能）。加工可以通过普通注射成型进行，材料非常适合增材制造，如3D打印。从模型聚合物废物流中选择性去除是可能的。

在该方法中，最初的聚合物是由长链结构的缩聚反应产生的，这些结构是通过最先进的催化方案从普通植物油原料或微藻油中提取的。这使得类聚乙烯材料的闭环回收成为可能。

附：英文原文

Title: Closed-loop recycling of polyethylene-like materials

Author: Manuel Huler, Marcel Eck, Dario Rothauer, Stefan Mecking

Issue&Volume: 2021-02-17

Abstract: Plastics are key components of almost any technology today. Although their production consumes substantial feedstock resources, plastics are largely disposed of after their service life. In terms of a circular economy1,2,3,4,5,6,7,8, reuse of post-consumer sorted polymers (‘mechanical recycling’) is hampered by deterioration of materials performance9,10. Chemical recycling1,11 via depolymerization to monomer offers an alternative that retains high-performance properties. The linear hydrocarbon chains of polyethylene12 enable crystalline packing and provide excellent materials properties13. Their inert nature hinders chemical recycling, however, necessitating temperatures above 600 degrees Celsius and recovering ethylene with a yield of less than 10 per cent3,11,14. Here we show that renewable polycarbonates and polyesters with a low density of in-chain functional groups as break points in a polyethylene chain can be recycled chemically by solvolysis with a recovery rate of more than 96 per cent. At the same time, the break points do not disturb the crystalline polyethylene structure, and the desirable materials properties (like those of high-density polyethylene) are fully retained upon recycling. Processing can be performed by common injection moulding and the materials are well-suited for additive manufacturing, such as 3D printing. Selective removal from model polymer waste streams is possible. In our approach, the initial polymers result from polycondensation of long-chain building blocks, derived by state-of-the-art catalytic schemes from common plant oil feedstocks, or microalgae oils15. This allows closed-loop recycling of polyethylene-like materials.

DOI: 10.1038/s41586-020-03149-9

Source: https://www.nature.com/articles/s41586-020-03149-9