Bio-based and recyclable adhesives based on β-hydroxyester bonds and hydrogen bonds via molecular dynamics simulation

The intelligent design and green manufacturing of bio-based adhesives still face severe challenges. In this study, an epoxy adhesive based on β-hydroxyester bonds and multiple hydrogen bonds was prepared using tung oil and lignin. Molecular dynamics simulation was used to regulate the structure and properties of adhesives. The adhesive with a large number of aromatic ring structures and phenolic hydroxyl groups enhanced cohesion and surface adsorption through π–π stacking and hydrogen bonding. Conjugated double bonds and the flexible long chain of tung oil in the structural skeleton of adhesives provided modification sites and endowed the materials with good ductility. The adhesive materials showed remarkable mechanical properties, recyclability, and an adhesive strength of approximately 6 MPa, enabling their effective use in various harsh environments, with a decrease in shear strength of only about 10%. Two adhesive models, one with β-hydroxyester bonds and multiple hydrogen bonds and the other without these structures, were established for comparison. The adhesion energy on the wood surface was calculated to assess the impact of each structural component in the system. In this study, a strategy to analyze the interplay between the microstructure and properties of adhesives was presented, and a potential route for the intelligent design and manufacturing of high-performance bio-based adhesives was provided.