Toward Recyclable Polymers: Ring-Opening Polymerization Enthalpy from First-Principles.

Ring-opening polymerization (ROP) enthalpy Δ H ROP is an important thermodynamic property controlling the polymerization of cyclic monomers. While Δ H ROP can be measured, computing Δ H ROP for realistic polymer systems with an error of ≃5-10 kJ/mol is critical for designing new monomer systems for depolymerizable polymers. We have developed a first-principles computational scheme in which multiple challenges in computing Δ H ROP are resolved definitively including extensive exploration of conformational states and adequately addressing finite size effects. This scheme is validated on a diverse benchmark set of 42 ROP polymers for which reliable experimental values of Δ H ROP are available. For this set, the Δ H ROP root-mean-square error is ≃7 kJ/mol, about 3-times smaller than conventional approaches. This development opens up new pathways to build up a high-quality database of Δ H ROP for downstream predictive machine-learning models and ultimately to accelerate the design of depolymerizable polymers with desired properties.