Block copolymer molecular design to address practical limitations to recycling polyolefin blends

• 成果类型: Article
• 署名作者: Cui, Shuquan; Jeong, Daun; Shi, Yukai; Jahan, Nusrat; Lodge, Timothy P.; Bates, Frank S.; Ellison, Christopher J.
• 署名单位: University of Minnesota System; University of Minnesota Twin Cities; University of Minnesota System; University of Minnesota Twin Cities
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-15246
• DOI: 10.1073/pnas.2508921122
• 发表日期: 2025-07-22
• 关键词: phase-behavior; tie chains; polyethylene; polypropylene; crystallization; waste; compatibilization; entanglement; morphology; SEPARATION

摘要

Plastics offer innumerable societal benefits but simultaneously contribute to persistent environmental pollution, dominated by polyethylene (PE) and isotactic polypropylene (iPP). Melt blending and reformulating postconsumer PE and iPP into useful materials presents a promising recycling approach. However, such repurposed plastics are generally mechanically inferior due to an inability to efficiently separate polyolefins in mixed waste streams; phase separation of PE and iPP results in brittleness as a consequence of poor interfacial strength. Recently, we demonstrated that a small amount (1 wt%) triblock copolymer, synthesized by low- cost anionic polymerization of 1,3- butadiene followed by solution hydrogenation, restores tensile toughness to levels equivalent to > 400% strain at break) was achieved in the present work with 1.5 <= EB <= 6.5, accompanied by reduced EXE crystallinity and dissolution in cyclohexane down to room temperature at the highest EB content. This remarkable toughening behavior is attributed to a homopolymer and formation of E block crystal nodules that prevent chain pullout, along with topological constraints between the X loops and semicrystalline iPP. Our findings overcome barriers to commercial production of EXE with existing industrial facilities, providing a cost- effective strategy for recycling PE and iPP.