Approaches to Sustainable and Continually Recyclable Cross-Linked Polymers

Cross-linked polymers are ubiquitous in daily life, finding applications as tires, insulation, adhesives, automotive parts, and countless other products. The covalent cross links in these materials render them mechanically robust, chemically resistant, and thermally stable, but they also prevent recycling of these materials into similar-value goods. Furthermore, cross-linked polymers are typically produced from petroleum based feedstocks, and their hydrocarbon backbones render them nondegradable, making them unsustainable in the long term. In recent years, much effort has focused on the development of recycling strategies for cross-linked polymeric materials. In the following Perspective, we discuss many of these approaches, and highlight efforts to sustainably produce recyclable cross linked polymers. We present our thoughts on future challenges that must be overcome to enable widespread, viable, and more sustainable and practical implementation of these materials, including the sustainable sourcing of feedstocks, long-term environmental stability of inherently dynamic polymers, and moving toward industrially viable synthesis and reprocessing methods.