Achieving ultrastrong adhesion of soft materials by discretized stress dispersion

Abstract

The adhesion of soft materials often fails due to stress concentration at the interface. Structural design offers an effective approach to disperse stress at the interface and enhance adhesion properties. Herein, we introduce the concept of discretized stress dispersion to achieve ultrastrong adhesion of soft materials. This involves incorporating discrete structures at the adhesion interface, with each unit structure designed to efficiently disperse stress. We implement this concept by introducing periodic strategic cuts into the adhesive, enabling it to deform into discrete mushroom-shaped structures under peel forces. Utilizing fracture mechanics theory, we demonstrate that such structural design can significantly improve adhesion strength compared to adhesives without structural design. Through 3D printing, we fabricate adhesive samples with strategic cuts, achieving a peak peel force of 3479 N/m, over 100-fold higher than adhesives without cuts (25 N/m). We analyzed stress dispersion of each unit structure through experiments of with different geometric parameters and analyze collaborative effects of multiple structures with theoretical model. Finite element analysis of the peel process highlights the critical role of cohesive zone influenced by geometric parameters, which determines the peak peel force. This concept of discretized stress dispersion advances the development of soft materials with ultrastrong adhesion.