title: The Influence of Surface Topography and Surface Chemistry on the Anti-Adhesive Performance of Nanoporous Monoliths.
abstract: We designed spongy monoliths allowing liquid delivery to their surfaces through continuous nanopore systems (mean pore diameter ∼40 nm). These nanoporous monoliths were flat or patterned with microspherical structures a few tens of microns in diameter, and their surfaces consisted of aprotic polymer or of TiO2 coatings. Liquid may reduce adhesion forces FAd; possible reasons include screening of solid-solid interactions and poroelastic effects. Softening-induced deformation of flat polymeric monoliths upon contact formation in the presence of liquids enhanced the work of separation WSe. On flat TiO2-coated monoliths, WSe was smaller under wet conditions than under dry conditions, possibly because of liquid-induced screening of solid-solid interactions. Under dry conditions, WSe is larger on flat TiO2-coated monoliths than on flat monoliths with a polymeric surface. However, under wet conditions, liquid-induced softening results in larger WSe on flat monoliths with a polymeric surface than on flat monoliths with an oxidic surface. Monolithic microsphere arrays show antiadhesive properties; FAd and WSe are reduced by at least 1 order of magnitude as compared to flat nanoporous counterparts. On nanoporous monolithic microsphere arrays, capillarity (WSe is larger under wet than under dry conditions) and solid-solid interactions (WSe is larger on oxide than on polymer) dominate contact mechanics. Thus, the microsphere topography reduces the impact of softening-induced surface deformation and screening of solid-solid interactions associated with liquid supply. Overall, simple modifications of surface topography and chemistry combined with delivery of liquid to the contact interface allow adjusting WSe and FAd over at least 1 order of magnitude. Adhesion management with spongy monoliths exploiting deployment (or drainage) of interfacial liquids as well as induction or prevention of liquid-induced softening of the monoliths may pave the way for the design of artificial surfaces with tailored contact mechanics. Moreover, the results reported here may contribute to better understanding of the contact mechanics of biological surfaces.
authors: Institut für Chemie neuer Materialien, Universität Osnabrück , Barbarastraße 7, 49069 Osnabrück, Germany.
authors: Anna
authors: A
authors: Eichler-Volf
authors: School of Power and Mechanical Engineering, Wuhan University , South Donghu Road 8, Wuchang, Wuhan 430072, Hubei China.
authors: Longjian
authors: L
authors: Xue
authors: Institut für Technische Chemie, Universität Leipzig , Linnéstraße 3-4, 04103 Leipzig, Germany.
authors: Gregor
authors: G
authors: Dornberg
authors: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University , Nanjing 210009, Jiangsu, China.
authors: He
authors: H
authors: Chen
authors: Functional Morphology and Biomechanics, Zoological Institute, Kiel University , Am Botanischen Garten 9, 24118 Kiel, Germany.
authors: Alexander
authors: A
authors: Kovalev
authors: Institut für Technische Chemie, Universität Leipzig , Linnéstraße 3-4, 04103 Leipzig, Germany.
authors: Dirk
authors: D
authors: Enke
authors: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University , Nanjing 210009, Jiangsu, China.
authors: Yong
authors: Y
authors: Wang
authors: Functional Morphology and Biomechanics, Zoological Institute, Kiel University , Am Botanischen Garten 9, 24118 Kiel, Germany.
authors: Elena V
authors: EV
authors: Gorb
authors: Functional Morphology and Biomechanics, Zoological Institute, Kiel University , Am Botanischen Garten 9, 24118 Kiel, Germany.
authors: Stanislav N
authors: SN
authors: Gorb
authors: Institut für Chemie neuer Materialien, Universität Osnabrück , Barbarastraße 7, 49069 Osnabrück, Germany.
authors: Martin
authors: M
authors: Steinhart
keywords: adhesion; atomic layer deposition; bioinspired materials; block copolymers; microspheres; porous materials; surfaces