Biorenewable and Circular Multifunctional Composite Polyester Based on Multi‐Scale, Multi‐Dimensional, and Multi‐Component Design

Abstract Bio‐based polyethylene furandicarboxylate (PEF) plays a vital role in high‐performance packaging material for plastic replacement. However, the poor toughness blocks its practical applications. Copolymerization modification can enhance the toughness of PEF but inevitably causes a decrease in strength and barrier properties. Although nanofillers can enhance the overall performance of PEF, the intrinsic incompatibility between inert inorganic nanomaterials and PEF leads to poor reinforcement effects. Herein, a polydopamine (PDA) nanosheets/poly(ethylene‐co‐1,4‐cyclohexanedimethylene 2,5‐furandicarboxylate) (PECF) (denoted as PDAP) composite polyester is developed through the regulation of molecular and interface structures. The strategy realizes the in situ entanglement of nanofillers with the PECF chain segments through interface hydrogen bonding. The structure enhancement by molecular copolymerization and the interface enhancement by reinforcements promote crystallization, orientation, and bridging of composite systems, respectively. Benefiting from this multi‐scale, multi‐dimensional, and multi‐component synergistical design, the resultant PDAP integrates high strength (85 MPa), high toughness (111%), and excellent gas barrier properties (i.e., O₂ 0.016 barrer, CO₂ 0.013 barrer, and H₂O 1.4×10⁻¹⁴ g cm cm⁻² sPa) that are much higher than bio‐based materials and most engineering plastics. Interestingly, such the PDAP also shows superior physical recyclable, UV‐shielding, and solvent‐resistant properties, making it promising competitive for plastic replacement for high‐performance and multifunctional packaging materials.