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 economy^{1,2,3,4,5,6,7,8}, reuse of post-consumer sorted polymers (‘mechanical recycling’) is hampered by deterioration of materials performance^9,10. Chemical recycling^1,11 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 cent^3,11,14. 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.

塑料是当今几乎所有技术的关键组成部分。尽管它们的生产消耗了大量的原料资源，但塑料在其使用寿命之后大部分被丢弃。在循环经济方面^{1,2,3,4,5,6,7,8}，消费后分类聚合物的再利用（“机械回收”）受到材料性能退化的阻碍^9,10。通过解聚成单体的化学回收^1,11提供了一种保留高性能特性的替代方案。聚乙烯的直链烃链¹²可实现结晶堆积并提供出色的材料性能¹³. 然而，它们的惰性阻碍了化学回收，因此需要高于 600 摄氏度的温度并以低于 10% 的收率回收乙烯^3,11,14. 在这里，我们表明具有低密度链内官能团作为聚乙烯链断裂点的可再生聚碳酸酯和聚酯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，并且在回收时完全保留了理想的材料特性（如高密度聚乙烯的特性）。可以通过普通的注塑成型进行加工，并且这些材料非常适合增材制造，例如 3D 打印。从模型聚合物废物流中选择性去除是可能的。在我们的方法中，最初的聚合物来自长链结构单元的缩聚，这些结构单元是由普通植物油原料或微藻油的最先进的催化方案衍生的¹⁵ . 这允许聚乙烯类材料的闭环回收。