High strength tung oil-based adhesive with outstanding wet adhesion for cellulose fiber paper

The development of bio-based adhesives is hindered due to poor wet adhesion with wet substrate, limited durability, and lack of recyclability. Herein, we report an amphiphilic silane-oil adhesive synthesized via a one-step coupling reaction between (3-aminopropyl)triethoxysilane (APTES) and tung oil anhydride (TOA). The amphiphilic molecular architecture of the APTES-TOA adhesive facilitates strong adhesion to cellulose fibers, attributed to the polar interactions of the hydrophilic domains and the water-repellent contribution of the hydrophobic moieties. Thus, the APTES-TOA adhesive endows cellulose fiber paper (CFP) with a tensile strength of up to 117.33 MPa. Mechanistically, interfacial adhesion is governed by ion-diffusion-induced formation of a mobile interphase in wet fiber networks, followed by in situ silicification that generates hierarchical mechanical interlocking with cellulose fibers. This dual-stage mechanism significantly enhances the tensile index, tear resistance (2.93 mN m² g^-1), and folding endurance (12-fold) of CFP. Moreover, the adhesive exhibits excellent reusability, retaining stable bonding performance over at least eight cycles. This work offers a generalizable strategy for designing high-performance, sustainable adhesives for cellulose-based materials and beyond.