title: Composite Pillars with a Tunable Interface for Adhesion to Rough Substrates.
abstract: The benefits of synthetic fibrillar dry adhesives for temporary and reversible attachment to hard objects with smooth surfaces have been successfully demonstrated in previous studies. However, surface roughness induces a dramatic reduction in pull-off stresses and necessarily requires revised design concepts. Toward this aim, we introduce cylindrical two-phase single pillars, which are composed of a mechanically stiff stalk and a soft tip layer. Adhesion to smooth and rough substrates is shown to exceed that of conventional pillar structures. The adhesion characteristics can be tuned by varying the thickness of the soft tip layer, the ratio of the Young's moduli and the curvature of the interface between the two phases. For rough substrates, adhesion values similar to those obtained on smooth substrates were achieved. Our concept of composite pillars overcomes current practical limitations caused by surface roughness and opens up fields of application where roughness is omnipresent.
authors.affiliation: INM-Leibniz Institute for New Materials , Campus D2 2, 66123 Saarbrücken, Germany.|Department of Materials Science and Engineering, Saarland University , Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: Sarah C L
authors.initials: SC
authors.lastname: Fischer
authors.affiliation: INM-Leibniz Institute for New Materials , Campus D2 2, 66123 Saarbrücken, Germany.|Department of Materials Science and Engineering, Saarland University , Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: Eduard
authors.initials: E
authors.lastname: Arzt
authors.affiliation: INM-Leibniz Institute for New Materials , Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: René
authors.identifier: http://orcid.org/0000-0002-9623-2118
authors.initials: R
authors.lastname: Hensel
keywords: composites; dry adhesives; fibrillar; interface curvature; roughness; tunable adhesion