Dynamically Cross‐Linking Soybean Oil and Low‐Molecular‐Weight Polylactic Acid toward Mechanically Robust, Degradable, and Recyclable Supramolecular Plastics

Abstract To promote the sustainable development of society, it is important to develop methods for facile fabrication of bio‐based plastics that are mechanically robust and capable of recycling and completely degrading in soil. In this study, such bio‐based supramolecular plastics are conveniently and cost‐effectively fabricated by cross‐linking epoxidized soybean oil (ESO) and low‐molecular‐weight polylactic acid (PLA) (≈2 kDa) with dynamic boroxines. The bio‐based supramolecular plastic, which is denoted as ESO‐PLA, exhibits a tensile strength of ≈43 MPa and is highly flexible and water‐resistant. After being stored in an environment with a 100% relative humidity for 10 days, the tensile strength of the plastic remains higher than polyethylene. Due to the reversibility of boroxines, the ESO‐PLA plastic can be conveniently processed into different shapes and products. Meanwhile, the plastic can be recycled multiple times for repeated usage by either hot‐pressing or solvent‐assisted depolymerization/repolymerization methods. Benefiting from the easy degradation of ESO and low‐molecular‐weight PLA, the breakage of boroxine cross‐links enables rapid and complete degradation of the plastics in soil within 60 days. Additionally, in vitro and in vivo tests prove that the ESO‐PLA plastic exhibits satisfactory biocompatibility, which extends its application in medicine, food, and cosmetics industries.