Chemical Recycling of Isocyanate-Based and Non-Isocyanate, Bio-Based Polythiourethane Vitrimers

Polythiourethane (PTU) networks are part of a growing class of materials known as vitrimers which possess the ability to be physically recycled by melt-state reprocessing despite possessing crosslinks. The implications these materials have on increased sustainability of thermosets, in addition to growing research demonstrating promising material properties, means that PTUs have the potential to begin replacing polyurethanes in a variety of applications. However, with the increasing turnover rate of new technologies and materials, methods to recycle the polymer into an entirely new material is needed. For this reason, finding ways to return the polymer to monomers and repolymerize them into new materials is an important subject of research. Here, we examine PTU depolymerization under alcohol solvolysis and explore ways to repolymerize the products of those reactions. Through proton NMR, results have shown promise in recovering monomer-like materials that have been successfully used for repolymerization, and DSC results demonstrate recovery of the polymer's original properties thus demonstrating the efficacy and sustainability potential of PTU vitrimers.