Role of Thin Film Adhesion on Capillary Peeling.

Abstract

The capillary force can peel off a substrate-attached film if the adhesion energy (<i>G</i>_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 <i>G</i>_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 <i>G</i>_w and experimentally show the critical adhesion (<i>G</i>_w,c) to scale with the water-film interfacial energy (≈0.7γ_fw), which corresponds well with our theoretical prediction of <i>G</i>_w,c = γ_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.