Feedstock-Driven Design of CO2 Sorbents via Chemical Upcycling of Plastics and Elastomers

Abstract Plastic and elastomer wastes are abundant, carbon-rich feedstocks. At the same time, carbon capture requires sorbents that perform under realistic temperatures, humidity, dilute CO2, and repeated regeneration. This review surveys feedstock-driven chemical upcycling routes that transform waste polymers into CO2 sorbents, while treating carbonization-derived physisorbents as a comparative benchmark and pragmatic fallback for chemically intractable or highly heterogeneous feedstocks. We frame “waste-to-sorbent” conversion as a feedstock-driven design problem in which inherited constitutional chemistry, network and morphology, formulation, and acquired chemistry—collectively termed chemical memory—govern feasible transformations and capture performance. We organize the literature by major feedstocks—PET, PVC, polystyrene, rubbers/tires, polyolefins, and mixed plastics—and compare physisorption- and chemisorption-dominant architectures with emphasis on binding-site accessibility, transport limits, humidity effects, impurity tolerance, oxidative stability, and regeneration windows. Because cross-study comparison is often hindered by inconsistent testing conditions and incomplete characterization of both starting feedstocks and resulting sorbents, we propose a mechanism-aware benchmarking framework and minimum reporting protocol centered on feedstock descriptors, application-relevant CO2 partial pressures, working capacity, accessible-site metrics (e.g., effective nitrogen/amine efficiency), ultramicropore descriptors, and durability under humid/impure cycling. These guidelines connect feedstock chemistry to deployable sorbent design and accelerate translation beyond headline capacities.