Informatics-Driven Design of Solvent Systems and Depolymerizable Polymer Materials for Improved Plastics Recycling*

High thermomechanical stability under a variety of conditions is desirable for many polymer applications, but this durability comes at the cost of insolubility, infusibility and non-recyclability. To address this problem, we must overcome the fundamental disconnect between polymer stability and facile reuse, reprocessing, degradation and recycling. This requires simultaneous innovation in materials design to expand the range of compositions that display high performance characteristics and in polymer degradation to reprocess such materials on demand. We address these through collaborative research focused on predicting polymer solubility to expand the processability of polymers and through dual-tunable and reprocessable composites. Focusing first on existing polymer materials, we examine improved methods for high throughput measurement of polymer solubility and integration with machine learning to enable selection of green solvents for processing and recycling. We also take it a step further to select parameters for dissolution and precipitation kinetics, examining how these tie to fundamental theories of polymer solubility. Finally, we look to expand the available plastics with desirable mechanical properties that are recyclable by designing composites with covalent adaptable networks that incorporate particles. The interplay of the bond exchange rate kinetics and the network relaxation both greatly influence the reprocessability kinetics, showing that in such systems both the physical and chemical dials can be used to tune the system. These new advances in understanding and design of processes for recycling plastics materials will enable progress towards sustainable plastics that also have high performance properties.