Recyclable Biophenolic Nanospheres for Sustainable and Durable Multifunctional Applications in Thermosets

Nanomaterials have a critical role in functional materials engineering; however, their efficient recycling, durable use, and multifunctional integration remain a huge challenge for sustainable development. Herein, we report multifunctional biophenolic nanospheres that exploit stimuli-responsive reversible assembly based on multiple directional interactions, allowing for closed-loop recycling and durability, even in complex systems of thermosets. The biobased nanospheres can serve long-term in various environments (high temperature, water, acid, surfactant solutions, etc.). By matching disassembly conditions, the nanospheres can be circularly dissociated into precursors, removed from application systems, reassembled, and reused sustainably. The corresponding mechanism is illustrated by experimental characterization and theoretical simulation. We further demonstrate the recycling and durable multifunctional effects of the nanospheres in thermoset foams. The reproducible nanospheres with diverse radical scavenging abilities endow nanocomposites with excellent mechanical enhancement, aging resistance, and durable flame retardancy. This study paves the way for tackling the pressing issue of high-value functional nanomaterial sustainability.