Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States.
J Am Chem Soc. 2022 Jul 20;144(28):12613-12618. doi: 10.1021/jacs.2c04499. Epub 2022 Jul 6.
Polyolefins represent the largest class of commodity materials due to their excellent material properties; however, they have limited pathways to chemical recycling and are often difficult to mechanically recycle. Here we demonstrate a new catalyst for the isoselective copolymerization of propylene and butadiene capable of favoring 1,4-insertion over 1,2-insertion while maintaining good molecular weights and turnover frequencies. This isotactic propylene copolymer with main-chain unsaturation was depolymerized to a telechelic macromonomer using an olefin metathesis catalyst and 2-hydroxyethyl acrylate. After hydrogenation, the telechelic macromonomer was repolymerized to form an ester-linked polypropylene material. This polymer shows thermal and mechanical properties comparable to linear low-density polyethylene. Finally, the telechelic macromonomer could be regenerated through the depolymerization of the ester-linked polypropylene material, which allows for the chemical recycling to macromonomer. This process provides a route to transform partially unsaturated polyolefins to chemically recyclable materials with similar properties to their parent polymers.
聚烯烃因其优异的材料性能而成为最大的商品材料类别；然而，它们的化学回收途径有限，而且通常难以机械回收。在这里，我们展示了一种新的用于丙烯和丁二烯的等规共聚的催化剂，该催化剂能够有利于 1,4-插入而不是 1,2-插入，同时保持良好的分子量和周转频率。这种具有主链不饱和的等规丙烯共聚物使用烯烃复分解催化剂和 2-羟乙基丙烯酸酯解聚为端基大分子单体。加氢后，端基大分子单体重新聚合形成酯键连接的聚丙烯材料。该聚合物表现出与线性低密度聚乙烯相当的热性能和机械性能。最后，通过酯键连接的聚丙烯材料的解聚可以再生端基大分子单体，从而实现从聚合物到大分子单体的化学回收。该工艺提供了一种将部分不饱和聚烯烃转化为具有与其母体聚合物相似性能的可化学回收材料的途径。
