Enhancing Polystyrene Circularity via Functionalized Weak Linkages

Polystyrene recycling remains a formidable challenge due to its robust full carbon backbone and the formation of impure monomer mixtures during depolymerization. Conventiosnal recycling approaches, including mechanical reprocessing, suffer from polymer degradation, excessive energy demands, and inefficient monomer recovery, severely limiting their industrial viability. Here, we introduce a simple strategy to enhance the circularity of polystyrene by incorporating bioderived muconate esters as selectively cleavable units within the polymer backbone. These units lower the activation energy of radical formation, which allows the polystyrene-copolymers to depolymerize at temperatures lower than that of pure polystyrene. The resulting polystyrene copolymers, even with minimal ME incorporation, units as low as 1%, undergo efficient monomer-to-monomer (M2M) depolymerization at distinctly reduced temperatures (280–300 °C). The copolymer generated via this process achieves styrene recovery with high purity (92–98%) while maintaining the mechanical and thermal properties of polystyrene. Importantly, this strategy is applicable to a broad range of polystyrene materials, including high-impact, general purpose, expanded, extruded, cross-linked polystyrene, and soft polystyrene formulations. By lowering the energy barrier for depolymerization while preserving polymer performance, this strategy establishes a robust, energy-efficient framework for achieving polystyrene circularity, offering a scalable solution to one of the most persistent challenges in plastic waste management.