Role of Thin Film Adhesion on Capillary Peeling

The capillary force can peel off a substrate-attached film if the adhesion energy (G(w)) is low. Capillary peeling has been used as a convenient, rapid, and nondestructive method for fabricating free-standing thin films. However, the critical value of G(w), which leads to the transition between peeling and sticking, remains largely unknown. As a result, capillary peeling remains empirical and applicable to a limited set of materials. Here, we investigate the critical value of G(w) and experimentally show the critical adhesion (G(w,c)) to scale with the water-film interfacial energy (approximate to 0.7 gamma(fw)), which corresponds well with our theoretical prediction of (Gw, c) =gamma(fw). Based on the critical adhesion, we propose quantitative thermodynamic guidelines for designing thin film interfaces that enable successful capillary peeling. The outcomes of this work present a powerful technique for thin film transfer and advanced nanofabrication in flexible photovoltaics, battery materials, biosensing, translational medicine, and stretchable bioelectronics.