title: Detachment of compliant films adhered to stiff substrates via van der Waals interactions: role of frictional sliding during peeling.
abstract: The remarkable ability of some plants and animals to cling strongly to substrates despite relatively weak interfacial bonds has important implications for the development of synthetic adhesives. Here, we examine the origins of large detachment forces using a thin elastomer tape adhered to a glass slide via van der Waals interactions, which serves as a model system for geckos, mussels and ivy. The forces required for peeling of the tape are shown to be a strong function of the angle of peeling, which is a consequence of frictional sliding at the edge of attachment that serves to dissipate energy that would otherwise drive detachment. Experiments and theory demonstrate that proper accounting for frictional sliding leads to an inferred work of adhesion of only approximately 0.5 J m(-2) (defined for purely normal separations) for all load orientations. This starkly contrasts with the interface energies inferred using conventional interface fracture models that assume pure sticking behaviour, which are considerably larger and shown to depend not only on the mode-mixity, but also on the magnitude of the mode-I stress intensity factor. The implications for developing frameworks to predict detachment forces in the presence of interface sliding are briefly discussed.
authors.affiliation: Department of Mechanical Engineering, University of California, Santa Barbara, CA, USA.
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Collino
authors.affiliation: Department of Materials, University of California, Santa Barbara, CA, USA.
authors.forename: Noah R
authors.initials: NR
authors.lastname: Philips
authors.affiliation: Department of Materials, University of California, Santa Barbara, CA, USA.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Rossol
authors.affiliation: Department of Mechanical Engineering, University of California, Santa Barbara, CA, USA Department of Materials, University of California, Santa Barbara, CA, USA School of Engineering, University of Aberdeen, King's College, Aberdeen AB24 3UE, UK INM-Leibniz Institute for New Materials, Campus D22, 66123 Saarbrücken, Germany.
authors.forename: Robert M
authors.initials: RM
authors.lastname: McMeeking
authors.affiliation: Department of Mechanical Engineering, University of California, Santa Barbara, CA, USA Department of Materials, University of California, Santa Barbara, CA, USA begley@engr.ucsb.edu.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Begley
mesh_terms: D000268:Adhesiveness; D000327:Adsorption / Q000528:radiation effects; D003198:Computer Simulation; D055119:Elastic Modulus; D017276:Friction; D008567:Membranes, Artificial; D008962:Models, Theoretical; D009038:Motion; D011829:Radiation Dosage; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial
keywords: digital image correlation; friction; peel test; poly (dimethylsiloxane); slip; thin-film adhesion