Pushing forward kinetic modeling tools for polymer circularity design and recycling

Polymer circularity has received increasing attention due to ecological benefits, by which plastic waste should be reused or converted into high-value products in an economic framework balanced with virgin polymer production. From a chemical engineering point of view, the understanding of reaction kinetics and chemical modifications plays a crucial role in improving the process towards polymer circularity. This reaction kinetics is connected to molecular variations for which (micro)kinetic models are essential. In this perspective, the main kinetic simulation methods are summarized, focusing on their respective characteristics and challenges, besides differentiating between deterministic and stochastic methods. The application of kinetic simulations in polymer circularity processes is clarified in the form of three case studies, including (i) mechanical recycling with deliberate chemical modification by reactive extrusion, (ii) chemical recycling aiming at monomer recovery, and (iii) recycling-by-design aiming at vitrimer molecular design. Attention is also paid to the relevance of benchmarking the methods applied.