No abstract

The development of chemically recyclable polymers with desirable properties is a long-standing but challenging goal in polymer science. Central to this challenge is the need for reversible chemical reactions that can equilibrate at rapid rates and provide efficient polymerization and depolymerization cycles. Based on the dynamic chemistry of nucleophilic aromatic substitution (S N Ar), we report a chemically recyclable polythioether system derived from readily accessible benzothiocane (BT) monomers. This system represents the first example of a well-defined monomer platform capable of chain-growth ring-opening polymerization through an S N Ar manifold. The polymerizations reach completion in minutes, and the pendant functionalities are easily customized to tune material properties or render the polymers amenable to further functionalization. The resulting polythioether materials exhibit comparable performance to commercial thermoplastics and can be depolymerized to the original monomers in high yields.

A depolymerizable vitrimer that allows both reprocessability and monomer recovery by a simple and scalable one‐pot two‐step synthesis of vitrimers from cyclic lactones is reported. Biobased δ‐valerolactone with alkyl substituents (δ‐lactone) has low ceiling temperature; thus, their ring‐opening‐polymerized aliphatic polyesters are capable of depolymerizing back to monomers. In this work, the amorphous poly(δ‐lactone) is solidified into an elastomer (i.e., δ‐lactone vitrimer) by a vinyl ether cross‐linker with dynamic acetal linkages, giving the merits of reprocessing and healing. Thermolysis of the bulk δ‐lactone vitrimer at 200 °C can recover 85–90 wt% of the material, allowing reuse without losing value and achieving a successful closed‐loop life cycle. It further demonstrates that the new vitrimer has excellent properties, with the potential to serve as a biobased and sustainable replacement of conventional soft elastomers for various applications such as lenses, mold materials, soft robots, and microfluidic devices.