Cyclobutane‐Programmed Sustainable Materials With Service‐Induced Self‐Reinforcement, Optical Security, and Closed‐Loop Chemical Recycling

ABSTRACT

High durability and fully recyclable materials represent a promising sustainable development strategy to address the escalating global plastic crisis, but there is always a trade‐off between aging resistance and easy chemical recycling. We present an unprecedented biomass‐derived polyester molecularly designed strategy that uniquely integrates service‐triggered antiaging self‐reinforcement with easy monomer‐level closed‐loop recyclability programmed with a cyclobutane mechanophore unit. During service, polyester undergoes a [2+2] cycloaddition that forms covalent cyclobutane cross‐links, creating an in situ self‐reinforcing network. This transformation increases oxygen‐barrier performance by up to 330% and improves tensile strength by 21%, enabling performance amplification rather than degradation. The same cyclobutane units are engineered to undergo mechanochemical cycloreversion, providing a force‐activated de‐cross‐linking pathway that allows complete monomer‐level depolymerization under mild conditions. The repolymerized materials are indistinguishable from the original. Additional features, including ultraviolet shielding and fluorescence‐based anti‐counterfeiting, highlight its multifunctionality. This biomass material demonstrates a unified molecular strategy that enables self‐reinforcement and efficient, easy recycling, offering a viable pathway for next‐generation sustainable polymers.