Enabling Circular Polymer Chemistry Through Computation

Monomer-to-monomer recycling is a promising solution to the global plastic pollution crisis. However, most conventional plastics are difficult to depolymerize due to the large energy input required to degrade a carbon-carbon backbone. Instead, one can design polymers to incorporate bonds that are reversible in specific processes. This work demonstrates how quantum chemistry tools can be used to develop design rules for bonds that enable monomer-to-monomer recycling. Specifically, design rules were discovered for an exciting new polymer platform, called poly(dikeotenamine)s, which has been shown to display chemical circularity with >90% monomer yield. Design rules were developed from analysis of the simulated reaction pathway for the acid-catalyzed hydrolysis of the polymer with several heteroatom substitutions of the basic platform. Considering the ubiquity of the addition-elimination reaction in depolymerization processes, this analysis can inform design of a wide variety of monomer-to-monomer recycling techniques.