Reversible Crosslinking of Commodity Polymers via Photo-Controlled Metal-Ligand Coordination for High-Performance And Recyclable Thermoset Plastics.

Thermoset plastics, highly desired for their stability, durability, and chemical resistance, are currently consumed over 60 million tons annually across the globe, but they are difficult to recycle due to their crosslinked structures. The development of recyclable thermoset plastics is an important but challenging task. Here, we prepare recyclable thermoset plastics by crosslinking a commodity polymer, polyacrylonitrile (PAN), with a small percentage of a Ru complex via nitrile-Ru coordination. PAN is obtained from industry and the Ru complex is synthesized in one step, which enables the production of recyclable thermoset plastics in an efficient way. Additionally, the thermoset plastics exhibit impressive mechanical performance, boasting a Young's modulus of 6.3 GPa and a tensile strength of 109.8 MPa. Moreover, they can be decrosslinked when exposed to both light and a solvent, and can then be re-crosslinked upon heating. This reversible crosslinking mechanism enables the recycling of thermosets from a mixture of plastic waste. We also demonstrate the preparation of recyclable thermosets from other commodity polymers such as SAN resins and polymer composites through reversible crosslinking. This study shows reversible crosslinking via metal-ligand coordination is a new strategy for designing recyclable thermosets using commodity polymers. This article is protected by copyright. All rights reserved.