title: Reversible adhesion switching of porous fibrillar adhesive pads by humidity.
abstract: We report reversible adhesion switching on porous fibrillar polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) adhesive pads by humidity changes. Adhesion at a relative humidity of 90% was more than nine times higher than at a relative humidity of 2%. On nonporous fibrillar adhesive pads of the same material, adhesion increased only by a factor of ~3.3. The switching performance remained unchanged in at least 10 successive high/low humidity cycles. Main origin of enhanced adhesion at high humidity is the humidity-induced decrease in the elastic modulus of the polar component P2VP rather than capillary force. The presence of spongelike continuous internal pore systems with walls consisting of P2VP significantly leveraged this effect. Fibrillar adhesive pads on which adhesion is switchable by humidity changes may be used for preconcentration of airborne particulates, pollutants, and germs combined with triggered surface cleaning.
authors.affiliation: Institut für Chemie neuer Materialien, Universität Osnabrück , Barbarastrasse 7, 49069 Osnabrück, Germany.
authors.forename: Longjian
authors.initials: L
authors.lastname: Xue
authors.forename: Alexander
authors.initials: A
authors.lastname: Kovalev
authors.forename: Kirstin
authors.initials: K
authors.lastname: Dening
authors.forename: Anna
authors.initials: A
authors.lastname: Eichler-Volf
authors.forename: Henning
authors.initials: H
authors.lastname: Eickmeier
authors.forename: Markus
authors.initials: M
authors.lastname: Haase
authors.forename: Dirk
authors.initials: D
authors.lastname: Enke
authors.forename: Martin
authors.initials: M
authors.lastname: Steinhart
authors.forename: Stanislav N
authors.initials: SN
authors.lastname: Gorb