Nitroarene-Mediated Photo-oxidative Deconstruction and Upcycling of Unsaturated Rubber Waste

Transforming waste polymers into materials with improved properties offers a compelling strategy for advancing the sustainable use of polymers, echoing the Chinese proverb: "Blue comes from indigo but surpasses it in blueness." Herein, we report a photo-oxidative deconstruction and upcycling method for unsaturated rubber waste. Under 390 nm LED irradiation at room temperature, in the presence of a nitroarene oxidant, diverse unsaturated polymersincluding natural rubber, polybutadiene, nitrile rubber, styrene-butadiene rubber, and even cross-linked nitrile glovesare selectively converted into carbonyl-terminated oligomers. The aldehyde-functionalized products are cross-linked via dynamic imine chemistry with p-phenylenediamine to yield reprocessable elastomers with markedly improved tensile strength (from 12.9 to 16.7 MPa) and surface hydrophobicity (contact angle from 23 ± 2° to 83 ± 3°). Furthermore, the aldehyde groups on the oligomers can be selectively oxidized to carboxylic acids or reduced to hydroxyl groups, enabling their versatile use as polymeric additives including curing agents, chain extenders, and toughening agents. This strategy demonstrates a versatile route for converting rubber waste into high-value functional materials.