Efficient Oxidative Upcycling of Waste Polyolefins into Functional Carboxylic Acid Additives over Non-Noble-Metal Catalysts

Abstract

Polyethylene (PE) and polypropylene (PP) are among the most commonly produced plastics, yet their chemical inertness poses a major challenge for sustainable waste management. Here, we report a cost-effective one-pot oxidative upcycling strategy that converts mixed polyolefin waste into oxygen-rich liquid products with yields exceeding 90% within 2 h using MnO2 under mild conditions (160 °C, 1.5 MPa air). The resulting liquids, consisting predominantly of saturated and unsaturated carboxylic acids, can be directly used as polymer additives without purification. When blended with polyvinyl alcohol (PVA), these crude oxidation products markedly enhance material performance, increasing flexibility by 150% and improving hydrophobicity, UV shielding, and antibacterial properties. Mechanistic investigations reveal that MnO2 promotes O2 activation and drives sequential C-H oxidation and chain-scission reactions, thereby enabling efficient depolymerization under low-energy conditions. The catalyst also shows excellent recyclability, further underscoring the practicality of the process. Overall, this work provides an efficient and economically viable route to transform polyolefin waste into functional additives and offers a promising strategy for value-added plastic upcycling.