Bioinspired Pressure Sensitive Adhesives Based on Natural Deep Eutectic Solvents

Petroleum-based pressure sensitive adhesives (PSAs) have been ruling the industry with their rigorous standards for adhesion strength and durability. While petrochemical PSAs have been the center of attention for many years, there is growing interest in developing biobased alternatives. In this study, a bioinspired PSA was developed combining natural deep eutectic solvents (NaDES) and hyaluronic acid, a biosourced polysaccharide, which has not been previously explored in PSA formulations. By leveraging the unique properties of NaDES, these soft materials derive their adhesive properties primarily from hydrogen bonds and physical cross-links arising from polymer chain entanglements. We investigate the role of hyaluronic acid in creating an elastic network within the viscous hydrogen-bonded NaDES, demonstrating tunable mechanical properties that depend on molecular weight and concentration. In parallel, we predict the adhesive properties of these materials from small amplitude oscillatory shear measurements. While such predictions show strong correlation with our experimental results, it remains necessary to support these predictions with nonlinear tack measurements, as such frameworks may not fully capture the behavior of soft supramolecular adhesives. Overall, the bioinspired adhesives presented in this work demonstrate tunable adhesion properties, highlighting their potential for further development as sustainable PSAs.