Mechanics of Heterogeneous Adhesion in Blistered Thin Films on Soft Solids: From Peeling to Rolling and the Discontinuous Transition Between

Blisters, tiny air pockets that form when adhesion fails between two surfaces, are a common but poorly understood phenomenon, appearing in contexts ranging from smartphone screen protectors to laminated aerospace composites. In soft adhesive systems, the removal of blistered films often leads to an unexpected transition from peeling to rolling, where one edge of the film detaches as the opposite edge spontaneously reattaches. This process is marked by discrete jumps in adhesion force and complex interfacial behavior that cannot be explained by traditional peeling mechanics. The goal of this project is to develop a comprehensive understanding of this peel-to-roll transition using a combination of experiments, analytical models, and numerical simulations. By revealing how geometric confinement and interfacial deformation can create spatially heterogeneous adhesion landscapes even between homogeneous materials, the research seeks to establish new strategies for controlling adhesion in soft and stretchable devices. Educational and outreach activities include a hands-on "Sticky Tapes" exhibit for children, a summer workshop for high school students, and research engagement opportunities for undergraduates. This project will investigate the mechanics of multi-step, heterogeneous adhesion through a detailed study of thin, blistered films partially bonded to soft substrates. Precision experiments will be used to identify the critical blister contact length that triggers the onset of rolling. Analytical modeling and finite element simulations will then be employed to determine how this rolling motion alters adhesion hysteresis and introduces discrete jumps in the force required for detachment. In parallel, the project will explore how blister geometry and spatial distribution can be engineered to program adhesion behavior across the interface. These results seek to yield fundamental insights into elasto-adhesive coupling in confined geometries and inform the design of novel soft interfaces in biomedical adhesives, flexible electronics, and soft robotics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.