Resin-to-Resin Circularity in Chemical Recycling of Dicyclopentadiene-Based Cycloolefin Resins
Zhen Xu, Mason L. Witko, Hongqian Zheng, Julia Im, Shira Haber, Ankita Ghosh, Maxwell C. Venetos, Jeffrey A. Reimer, Kristin A. Persson, Brett A. Helms
Abstract
Cycloolefin resins (CORs) comprising dicyclopentadiene (DCPD) cross-linkers are high performance thermosets for diverse single-use applications. If it were possible to carry out deconstruction of DCPD thermosets through exclusive reformation of the cyclopentene ring in DCPD, then linear polyDCPD chains could re-enter subsequent manufacturing cycles and enable resin-to-resin circularity. Here, we develop a chemical recycling process whereby linear polyDCPD recyclates are generated from end-of-life commercial and model CORs, including copolymers, using a second-generation Hoveyda-Grubbs ruthenium(II) alkylidene catalyst for deconstruction via ring-closing metathesis. The properties of first-generation DCPD thermosets were reproduced across subsequent generations of recycling and reuse, where up to 84% of linear DCPD was retrievable from end-of-life thermosets after deconstruction. We further quantify how comonomer incorporation, the curing process, and aging affect round-trip material efficiency and the quality of regenerated thermosets.