Selective Mechanical Deconstruction of Multilayer Film Interfaces

Studies have investigated the use of mechanically heterogeneous interfaces having compliant and rigid components for control of adhesion strength. From Kirigami-inspired tapes to composite micropillars. In a similar fashion, mechanically heterogeneous interfaces can be used to trigger delamination events due to localization of stress at the rigid-soft interface. This is especially useful for improving the circularity of multilayer films, which are difficult to recycle due to their multi-material chemistry and use of tie layer adhesives that prevent facile separation of the layers. I will present a material design that utilizes mechanically heterogeneous interfaces that when coupled with a mechanical trigger, selectively deconstructs a multilayer film. Rigid silica microparticles are placed at the tie layer (polyethylene acrylic acid (PEAA)) and aluminum foil interface of a tri-layer film comprised of polycarbonate, PEAA, and aluminum foil. A high intensity ultrasound pulse is sent through the sample, taking care to select a wavelength and voltage that will generate a pressure wave capable of generating significant mechanical stresses at the interfaces. Delamination of the foil layer was observed when 5 µm size particles were positioned at the interface and subjected to an ultrasound pulse, while no delamination was observed if no particles were used, suggesting that interfacial patterning with mechanically heterogenous particles assists in delamination of the layers. Additionally, particle size, density, and location of within the bulk of the material play a significant role in the delamination mechanism. In this work, we design our multilayer materials with end-of-life in mind in order to improve recovery and reuse of layers used in multilayer films.