Threading-the-Needle: Compatibilization of HDPE/ i PP blends with butadiene-derived polyolefin block copolymers

作者：Liyang Shen, Gabriela Díaz Gorbea, Evan Danielson, Shuquan Cui, Christopher J. Ellison, Frank S. Bates · 发表于：Proceedings of the National Academy of Sciences · 年份：2023 · DOI：10.1073/pnas.2301352120 · 被引用次数：65 · 研究领域：Polymer crystallization and properties、biodegradable polymer synthesis and properties、Microplastics and Plastic Pollution

Management of the plastic industry is a momentous challenge, one that pits enormous societal benefits against an accumulating reservoir of nearly indestructible waste. A promising strategy for recycling polyethylene (PE) and isotactic polypropylene ( i PP), constituting roughly half the plastic produced annually worldwide, is melt blending for reformulation into useful products. Unfortunately, such blends are generally brittle and useless due to phase separation and mechanically weak domain interfaces. Recent studies have shown that addition of small amounts of semicrystalline PE- i PP block copolymers (ca. 1 wt%) to mixtures of these polyolefins results in ductility comparable to the pure materials. However, current methods for producing such additives rely on expensive reagents, prohibitively impacting the cost of recycling these inexpensive commodity plastics. Here, we describe an alternative strategy that exploits anionic polymerization of butadiene into block copolymers, with subsequent catalytic hydrogenation, yielding E and X blocks that are individually melt miscible with PE and i PP, where E and X are poly(ethylene- ran -ethylethylene) random copolymers with 6 wt% and 90 wt% ethylethylene repeat units, respectively. Cooling melt blended mixtures of PE and i PP containing 1 wt% of the triblock copolymer EXE of appropriate molecular weight, results in mechanical properties competitive with the component plastics. Blend toughness is obtained through interfacial topologi...