Fatigue-resistant adhesion through high energy barriers

Abstract

The applications of soft materials in various fields often require interfacial adhesion to sustain prolonged static or cyclic loads, whereas most existing adhesives are susceptible to fatigue failure. Unlike in a quasistatic debonding process, which depends more on the average resistance, the key to preventing fatigue crack propagation is to build up high energy barriers locally. Herein, we invoke three types of structural designs to induce large energy barriers at the interface to achieve fatigue-resistant adhesion. By varying the local bending stiffness of the backing layer, locally altering the fracture mode through kirigami patterns, or hindering crack initiation with simple edge notches, we enhanced the fatigue thresholds of various adhesives against peeling by several orders of magnitude, reaching record-breaking values. To verify the proposed mechanism and reveal the details of these remarkable enhancements, we develop theoretical models to study the peeling processes. Based entirely on structural design, the proposed mechanism is non-material-specific and universally applicable to various intermolecular interactions under any harsh environment, such as high temperature, high humidity, and physiological environments. We envision that the strategy and methodologies presented can pave the avenue of future adhesion designs for both durability and reliability.