Reprocessable and ultratough epoxy thermosetting plastic

• Published in: Nature sustainability 2024-06, Vol.7 (6), p.804-811
• Main Authors: Wu, Wenxuan, Feng, Haijun, Xie, Lulin, Zhang, Anyang, Liu, Feng, Liu, Zenghe, Zheng, Ning, Xie, Tao
• Format: Article
• Language: English
• Subjects: 639/301/1023/303; 639/638/224/685; 639/638/298/303; 639/638/455/303; Amines; Curing; Earth and Environmental Science; Environment; Plastics; Polymers; Sustainability; Sustainable Development
• ISSN: 2398-9629; 2398-9629
• DOI: 10.1038/s41893-024-01331-9

Due to their exceptional manufacturability and excellent mechanical properties, epoxy thermosets are one of the most widely used plastics, finding many industrial applications. However, the crosslinked polymer network renders them inherently brittle and not recyclable, raising sustainability concerns. Here we show epoxy thermosets with combined high toughness and reprocessability by innovating the chemistry of curing, a crosslinking process in polymers. Specifically, taking advantage of a one-pot epoxy curing mechanism with a boronic-ester-containing aromatic diamine crosslinker and an aliphatic monoamine, the stepwise reaction of the amines affords unique nanoscale phase separation. As a result, the epoxy thermoset exhibits maximum elongation of 375% and tensile toughness of 108.4 MJ m −3 , more than one order of magnitude higher than that of the conventional counterparts. Moreover, the introduced dynamic boronic ester bonds endow the thermoset with unusual reprocessability for extended service life, while other properties are not compromised notably after four cycles. The feasibility to simultaneously overcome the two major bottlenecks for epoxy thermosets opens opportunities to recycle and reinvent other industrially relevant plastics. Utilizing an epoxy-amine chemistry, the authors demonstrate a thermoset epoxy that is reprocessable and tough, achieving improved sustainability for this widely used plastic material.