Cartilage-inspired boronic ester dynamic cross-linking networks for high-strength and reversible adhesives

Achieving simultaneous exceptional adhesion and recyclability remains a formidable challenge due to the inherent strength-toughness trade-off and stability-switchability conflict in adhesive systems. Inspired by the hierarchical architecture of cartilage, we report a bioinspired cross-linked network integrating B-N coordination bonds and dynamic boronic ester linkages for high-performance recyclable adhesives. The biomimetic design replicates the structural organization of cartilage's collagen-proteoglycan matrix, where dynamic B-N coordination bonds between network junctions facilitate energy dissipation through bond dissociation-induced network elongation. The network is constructed via 3-amino-1,2-propanediol-mediated epoxy ring-opening and subsequent cross-linking with 1,4-phenylenediboronic acid, forming a dynamic covalent polymer network, denoted as BEAD (boronic ester adhesive), with high cross-linking density. BEAD exhibits exceptional mechanical properties (46.42 ± 5.32 MPa tensile strength, 2.60 ± 0.31 MJ/m³ toughness) and robust adhesion (26.69 ± 0.74 MPa lap shear strength on steel). The synergy of B-N coordination (enhancing cohesion) and boronic ester exchange (enabling reprocessability) yields an optimal balance of strength and recyclability, retaining 80.7% adhesion performance after five reprocessing cycles. The study presents a biomimetic dynamic bonding strategy to overcome the strength-recyclability trade-off in adhesives, establishing a sustainable paradigm for structural materials.