Sustainable Polyester Hot-Melt Adhesives with Tunable Adhesion Performance

The development of robust, sustainable hot-melt adhesives derived from renewable biobased resources remains a significant challenge. In this work, we designed a robust adhesive system fabricated via a catalyst-free Knoevenagel condensation between vanillin and cyanoacetic acid derivatives. The resulting adhesive exhibited robust performance and offered a sustainable alternative to conventional polyester adhesives. By simply adjusting the polymerization time, the optimized formulation (PCC-CM1212–6) exhibited exceptional adhesion strength, achieving 20.6 MPa on iron substrates and sustaining an 18 kg load in glass-wood lap-shear joints without failure─performance surpassing most reported polyester hot-melt adhesives. Remarkably, the adhesive maintained >17 MPa strength after 24 h exposure to acids, alkalis, and common solvents and retained approximately 85% of its original strength through four reuse cycles. Theoretical analyses of interfacial electrostatic potential and binding energy provided mechanistic insights into the high adhesion performance. Theoretical analyses of interfacial electrostatic potential and binding energy provided mechanistic insights into the high adhesion performance. This work provides a scalable solution to the challenge of developing high-performance biobased adhesives, demonstrating a viable path toward sustainable material alternatives with competitive durability.