MEAM Seminar: “Dynamically Tunable Adhesion and Friction via Active Materials with Thermally Modulated Stiffness”

Contact interactions, including adhesion and friction, are critical to the design of many engineered systems. Currently, most systems rely on materials with static mechanical properties, requiring careful selection of materials to realize effective systems for specialized tasks. However, with advances in smart materials, system design is no longer limited to materials with static properties. There is a significant potential to exploit active materials for dynamic control of mechanical behaviors, including adhesion and friction, to enable the design of systems with improved performance and new functionalities. Example applications of such systems are robotic grasping and manipulation. In this work, active control of adhesion and friction is realized using materials with tunable stiffness. In particular, thermally responsive polymers, which exhibit substantial changes in stiffness, provide significant potential for adhesion and friction control. We demonstrate the use of a shape memory polymer with thermally modulated stiffness to dynamically tune adhesion and friction. Through a combination of experimentation and finite element analysis, we present a composite microstructured adhesive with high strength and adhesion switchability, while highlighting the role of scale in achieving fast response times. Through further experimentation, we investigate the ability to tune friction, using stiffness modulation to enable a transition from Coulomb friction to adhesion-dominated friction. This ability to dynamically control adhesion and friction offers new opportunities for the design of engineered systems.