(274d) Multiscale Models for the Kinetics of Polymer Upcycling

Polymer upcycling is a potential solution to the abundance and persistence of plastic wastes in the natural environment. Starting from elementary steps and rate constants, we use pseudo-steady-state approximations and kinetic local density approximations to systematically transform mechanistic proposals into population balance models for time evolution of the molecular weight distribution. We examine homogeneous and heterogeneous catalysts, including catalysts that cut randomly, catalysts that cut processively, and catalysts that cut cooperatively. In the case of heterogeneous catalysis, we will discuss the critical importance of polymer adsorption isotherms. Finally, using experimental data on polyethylene upcycling, we show how these models can help to interpret experimental data, to test mechanistic proposals, and to extract kinetic parameters.