Enabling Circular Polymers Through Computational Design

Monomer-to-monomer recycling is a promising solution to the global plastic pollution crisis but is not feasible for most conventional plastics due to the difficulty of selectively cleaving a carbon-carbon backbone. One solution is to design polymers to incorporate bonds that can be selectively broken in specific chemical processes. This work demonstrates how computational tools can be used to develop mechanistic insights into how bond chemistry enables monomer-to-monomer recycling. Specifically, we used both classical and quantum methods to simulate the acid-catalyzed hydrolysis mechanism that enables recycling of a new polymer platform, poly(dikeotenamine)s (PDKs), which have been shown to display chemical circularity with >90% monomer yield. We find that the depolymerization rate of PDKs can be greatly varied through heteroatom and functional group substitutions on the monomer and crosslinker. This variance in depolymerization rate arises from unique mechanisms depending on the type and location of chemical substitution; thus, we used simulations across a range of length and time scales in order to examine a range of effects. By understanding how chemical bonding affects PDK recycling, we design the chemistry of PDKs to target specific properties while retaining recyclability. We discuss several cases in which computational and experimental design worked in close collaboration to develop diverse PDK formulations.