Dense H-Bonding Enhanced Bio-Based Supramolecular Adhesive: High Adhesive Strength and Multi-Reusability

Abstract

In response to the growing need for sustainable practices in the chemical industry, this study explores the development of biobased supramolecular adhesives (BSA) derived from renewable sources. Traditional synthetic adhesives, while effective, pose environmental and health concerns. Biobased adhesives offer a promising alternative, drawing inspiration from ancient practices of using natural substances for bonding. By combining biobased molecules such as tannic acid (TA), malic acid (MA), and citric acid (CA) through hydrogen bonding, supramolecular adhesives were synthesized. Notably, the adhesive properties were enhanced by adjusting the density of noncovalent interactions, particularly hydrogen bonds. Through comprehensive characterization techniques including NMR, Fourier-transform infrared (FTIR), rheology, and lap-shear strength test, the adhesive's structural and mechanical properties were elucidated. Lap shear strength tests demonstrated the superior performance of BSA based on CA over MA, attributed to its higher hydrogen bond density. Rheological studies revealed the adhesive's gel-like behavior and stability under stress. Moreover, the BSA constructed by CA exhibited robust bonding to metallic substrates and demonstrated resistance to organic solvents. Importantly, the adhesive maintained strong adhesion even after multiple reuse cycles. Additionally, it displayed remarkable thermal responsiveness and frost resistance, further highlighting its potential for diverse applications. This research underscores the feasibility and promise of biobased supramolecular adhesives as sustainable alternatives in adhesive technology.