Structural and tribometric characterization of biomimetically inspired synthetic "insect adhesives"

• Matthias W. Speidel,
• Malte Kleemeier,
• Andreas Hartwig,
• Klaus Rischka,
• Angelika Ellermann,
• Rolf Daniels and
• Oliver Betz

Beilstein J. Nanotechnol. 2017, 8, 45–63, doi:10.3762/bjnano.8.6

• adhesive fluids produced by glandular systems underlying the adhesive cuticular structures [2][3][4]. One major function of these liquid adhesives is to wet and maximize the contact area with the substrate by filling its surface irregularities [5][6]. In addition, viscous and capillary forces are conveyed

When the going gets rough – studying the effect of surface roughness on the adhesive abilities of tree frogs

• Niall Crawford,
• Thomas Endlein,
• Jonathan T. Pham,
• Mathis Riehle and
• W. Jon P. Barnes

Beilstein J. Nanotechnol. 2016, 7, 2116–2131, doi:10.3762/bjnano.7.201

• specialised morphology allow the tree frogs to climb smooth vertical and overhanging surfaces. The attachment ability of tree frogs is affected by both surface chemistry and surface roughness. Hydrophobic leaves (such as those on lotus leaves [4]), could affect the capillary forces produced by the pad (which

• capillary forces will be reduced due to a decline in the Laplace pressure component of capillarity [7]. Bhushan’s ‘submerged‘ regime is that of a rock/torrent frog climbing water-covered rock, where the toe pads are completely submerged, thus abolishing any meniscus [8]. In such cases, capillary forces will

• wetted. However, on a smooth surface the presence of water leads to a drop in their climbing abilities, particularly frictional forces. Discussion Tree frog adhesion Most evidence supports the hypothesis that tree frogs adhere by capillary forces [2][13][22], but roles for other adhesive mechanisms (such

Annealing-induced recovery of indents in thin Au(Fe) bilayer films

• Anna Kosinova,
• Ruth Schwaiger,
• Leonid Klinger and
• Eugen Rabkin

Beilstein J. Nanotechnol. 2016, 7, 2088–2099, doi:10.3762/bjnano.7.199

• processes in the material controlled by capillary forces [10][11] or the interaction of defects [12]. The healing capability of defects was recently demonstrated for Au [13] and Fe [14] nanoparticles. It was shown that the controlled injection of dislocations into single-crystalline faceted metal

Solvent-mediated conductance increase of dodecanethiol-stabilized gold nanoparticle monolayers

• Patrick A. Reissner,
• Jean-Nicolas Tisserant,
• Antoni Sánchez-Ferrer,
• Raffaele Mezzenga and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2016, 7, 2057–2064, doi:10.3762/bjnano.7.196

• for 10 s. From Figure 4, we can conclude that the compaction process is completed within one hour. This excludes that capillary forces originating from a drying solvent meniscus cause the compaction of the monolayer, because it would be independent of the immersion duration. The observed time

Surface roughness rather than surface chemistry essentially affects insect adhesion

• Matt W. England,
• Tomoya Sato,
• Makoto Yagihashi,
• Atsushi Hozumi,
• Stanislav N. Gorb and
• Elena V. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1471–1479, doi:10.3762/bjnano.7.139

• also produce capillary forces. Inspired by this idea, artificial silicone polymer structures with underwater adhesive properties were fabricated [34]. Thus, the relationship between surface structures and the attachment of insects, in combination with their particular chemical/physical properties, has

Influence of ambient humidity on the attachment ability of ladybird beetles (Coccinella septempunctata)

• Lars Heepe,
• Jonas O. Wolff and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1322–1329, doi:10.3762/bjnano.7.123

• capillary forces (wet adhesion). The fluid can increase the contact area by filling minute cavities of micro- and nano-rough surfaces, where setae otherwise cannot adapt to, and prevents slipping of the foot due to its specific rheological properties [31][32][33][34][35]. It was demonstrated that the

• adhesive pads of spiders and geckos the humidity-related effects on adhesion can be explained by three different mechanisms: (1) capillary forces due to the formation of liquid bridges; (2) changes in the effective short-range interactions due to adsorbed monolayers of water on the substrate [11][14]; (3

• affect the attachment ability in this case, since the contact is mediated by the tarsal secretion and not by a solid–solid contact. Coming back to the abovementioned mechanisms of capillary forces and/or changes in the effective short-range van der Waals interaction, which might influence the humidity

Mesoporous hollow carbon spheres for lithium–sulfur batteries: distribution of sulfur and electrochemical performance

• Anika C. Juhl,
• Artur Schneider,
• Boris Ufer,
• Torsten Brezesinski,
• Jürgen Janek and
• Michael Fröba

Beilstein J. Nanotechnol. 2016, 7, 1229–1240, doi:10.3762/bjnano.7.114

• pores are blocked by sulfur and thus, are no longer accessible for nitrogen gas during the measurements. We believe that the strong capillary forces on liquids/melts in the mesopores are responsible for the pore blocking effect. Once sulfur has filled the mesopores there is no further driving force for

Correlative infrared nanospectroscopic and nanomechanical imaging of block copolymer microdomains

• Benjamin Pollard and
• Markus B. Raschke

Beilstein J. Nanotechnol. 2016, 7, 605–612, doi:10.3762/bjnano.7.53

• or capillary forces). It can reflect variations in the Hamaker constant of the van der Waals interaction, surface charges, or hydrophilicity [32]. It has been observed in PS-b-PMMA that PS preferentially adsorbs onto a gold surface compared to PMMA [33]. Thus, the higher attractive forces over PS

• operating in the repulsive capillary force regime. Tip–surface capillary forces are most studied in the context of resonant cantilever motion instead of the slower, nonresonant distance modulation employed in PF-QNM. Nonetheless, our modulation amplitude (15 nm), measured tip radius (16–25 nm), and the

• relative humidity during the measurement (13%) indicate that we are operating near the threshold between attractive and repulsive regimes [30]. The delicate balance between repulsive capillary forces and overall van der Waals interaction could result in the finer variations across the PMMA microdomain. We

Stiffness of sphere–plate contacts at MHz frequencies: dependence on normal load, oscillation amplitude, and ambient medium

• Jana Vlachová,
• Rebekka König and
• Diethelm Johannsmann

Beilstein J. Nanotechnol. 2015, 6, 845–856, doi:10.3762/bjnano.6.87

• coefficients (determined from Δf(u0) and ΔΓ(u0)) is better in water than in air. We suspect that capillary forces affect ΔΓ(u0) stronger than Δf(u0). A more detailed discussion of the matter would require an extension of the Cattaneo–Mindlin model by specific contributions from different forces. Such an

• first category of problems originates from the numerous assumptions in the formulation of the model. For example, the normal pressure is assumed to stay constant during tangential loading. A second set of limitations is related to the idealized conditions. The CM model ignores roughness, capillary

• forces, plastic deformation, and the effects of contamination. In particular, plastic deformation can lead to junction growth, which stiffens the contact rather than weakening it [12][13]. There is a particular shortcoming that is on the one hand widely observed, but also easily fixed on a heuristic

Capillary and van der Waals interactions on CaF₂ crystals from amplitude modulation AFM force reconstruction profiles under ambient conditions

• Annalisa Calò,
• Oriol Vidal Robles,
• Sergio Santos and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2015, 6, 809–819, doi:10.3762/bjnano.6.84

• ]. This is particularly true when working in air under ambient conditions, where the presence of thin layers of water is ubiquitous even on highly hydrophobic surfaces [8][9][10] and specific interactions (hydration, capillary forces) [11] need to be accounted for, which can be effective at relatively

• equation [31], and the ΔΦ vs distance evolution [27]. Our results indicate that standard expressions for capillary forces based on a constant chemical potential can also be a valuable tool to predict the experimental phenomena observed in dynamic AFM [14]. Results Figure 1a and Figure 1b show AFM images of

Filling of carbon nanotubes and nanofibres

• Reece D. Gately and
• Marc in het Panhuis

Beilstein J. Nanotechnol. 2015, 6, 508–516, doi:10.3762/bjnano.6.53

• employed to produce SWCNTs [67] and VGCNFs [68], as well as long (10 µm) MWCNTs that can be nested or joined to create long MWCNTs [69]. The three primary methods for opening TCNSs are: electrochemical filling, functionalization of the TCNSs, and a method that takes advantage of the capillary forces within

• filling It is well known that a tubular structure with a high aspect ratio will have strong capillary forces, and this is especially true for TCNSs [87][88]. These forces can be exploited to achieve the filling of TCNSs. Capillary filling was achieved by depositing drops of metallic lead onto the external

Exploiting the hierarchical morphology of single-walled and multi-walled carbon nanotube films for highly hydrophobic coatings

• Francesco De Nicola,
• Paola Castrucci,
• Manuela Scarselli,
• Francesca Nanni,
• Ilaria Cacciotti and
• Maurizio De Crescenzi

Beilstein J. Nanotechnol. 2015, 6, 353–360, doi:10.3762/bjnano.6.34

• evaporative drying of single-walled carbon nanotube film during its preparation [36][37][41]. The out-of-plane assembly is the result of the competition between attractive capillary forces and bending stress due to the elasticity of SWCNT film. Once the liquid is completely evaporated, a pattern of micrometer

The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness

• Daniel Gandyra,
• Stefan Walheim,
• Stanislav Gorb,
• Wilhelm Barthlott and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2015, 6, 11–18, doi:10.3762/bjnano.6.2

• cantilevers, reproducing the spring constants calibrated using other methods. Keywords: adhesion; AFM cantilever; air layer; capillary forces; hairs; measurement; micromechanical systems; microstructures; Salvinia effect; Salvinia molesta; sensors; stiffness; superhydrophobic surfaces; Introduction Surface

Aquatic versus terrestrial attachment: Water makes a difference

• Petra Ditsche and
• Adam P. Summers

Beilstein J. Nanotechnol. 2014, 5, 2424–2439, doi:10.3762/bjnano.5.252

• , lock, clamp and spacer) significant differences have to be considered under water. For example, the main principles of dry adhesion, van der Waals forces and chemical bonding, which make a gecko stick to the ceiling, are weak under submerged conditions. Capillary forces are very important for wet

• in a terrestrial environment, especially in form of capillary forces. The aquatic or immersed environment is one in which water surrounds the organism completely, or at least the entire attachment organ and the attachment surface. Here, water plays a central role and must be considered to be

• [19][39]. If a fluid film is present, we have the conditions of wet adhesion. In wet adhesion two other forces contribute considerably to adhesion: (vi) capillary forces, and (vii) viscous forces. The latter is often called Stefan adhesion. A special case of wet adhesion is the secretion of adhesives

Synthesis of Pt nanoparticles and their burrowing into Si due to synergistic effects of ion beam energy losses

• Pravin Kumar,
• Udai Bhan Singh,
• Kedar Mal,
• Sunil Ojha,
• Indra Sulania,
• Dinakar Kanjilal,
• Dinesh Singh and
• Vidya Nand Singh

Beilstein J. Nanotechnol. 2014, 5, 1864–1872, doi:10.3762/bjnano.5.197

• islands [20][28]. However, other effects such as ion-induced viscous flow, recoil implantation and thermodynamically driven capillary forces can also contribute to the formation of the buried NPs. When the ion beams with high electronic energy loss (dominates at high energies) pass through the material, a

Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1649–1663, doi:10.3762/bjnano.5.176

• can obscure or hinder the measurement of viscoelasticity by using intermittent-contact methods. Well-known interactions of this type include capillary forces [44], plastic behaviors [45], chemical adhesion and topographical artifacts [46] and even geometry-driven physical adhesion artifacts. As

Physical principles of fluid-mediated insect attachment - Shouldn’t insects slip?

• Jan-Henning Dirks

Beilstein J. Nanotechnol. 2014, 5, 1160–1166, doi:10.3762/bjnano.5.127

• , undeformable disk and substrate with a mediating continuous fluid-layer (see Figure 2 and [30][38][39][40][41][42]). In this simple model, the total adhesive force is basically the sum of three components: the surface tension of the fluid, the Laplace pressure (both often combined as “capillary forces”) and

Fibrillar adhesion with no clusterisation: Functional significance of material gradient along adhesive setae of insects

• Stanislav N. Gorb and
• Alexander E. Filippov

Beilstein J. Nanotechnol. 2014, 5, 837–845, doi:10.3762/bjnano.5.95

• capillary forces. For the sake of simplicity we simulate it by the gradient of Morse potential UvdW(r) = U0(1 – exp(−r/r0))2, where r is a distance between the end of fiber and surface, with physically reasonable amplitude U0 = 10 nN·nm and the minimum located at the distance r0 = 0.01 µm from the surface

Dynamic nanoindentation by instrumented nanoindentation and force microscopy: a comparative review

• Sidney R. Cohen and
• Estelle Kalfon-Cohen

Beilstein J. Nanotechnol. 2013, 4, 815–833, doi:10.3762/bjnano.4.93

• [82][94]. One caveat arising from the modulation techniques is that the phase lag signal carries information on additional dissipative processes other than viscoelastic energy dissipation, such as surface adhesion and capillary forces [95]. “On-the-fly” measurements of dissipation, which integrate the

Porous polymer coatings as substrates for the formation of high-fidelity micropatterns by quill-like pens

• Michael Hirtz,
• Marcus Lyon,
• Wenqian Feng,
• Andrea E. Holmes,
• Harald Fuchs and
• Pavel A. Levkin

Beilstein J. Nanotechnol. 2013, 4, 377–384, doi:10.3762/bjnano.4.44

• ). After filling of the reservoir on the SPT with the dye solution, it is brought into contact with the substrate surface for a defined dwell time to allow a flow to the substrate by capillary forces. The SPT is retracted and moved to the next spotting position. The process of relocation, contacting and

Functionalization of vertically aligned carbon nanotubes

• Eloise Van Hooijdonk,
• Carla Bittencourt,
• Rony Snyders and
• Jean-François Colomer

Beilstein J. Nanotechnol. 2013, 4, 129–152, doi:10.3762/bjnano.4.14

Colloidal lithography for fabricating patterned polymer-brush microstructures

• Tao Chen,
• Debby P. Chang,
• Rainer Jordan and
• Stefan Zauscher

Beilstein J. Nanotechnol. 2012, 3, 397–403, doi:10.3762/bjnano.3.46

• : atom-transfer radical polymerization; colloidal lithography; patterning; self-assembled microsphere monolayer; Introduction It is well known that monodisperse colloidal microspheres easily self-assemble into hexagonally close-packed arrays on surfaces as a result of capillary forces arising from the

Hierarchically structured superhydrophobic flowers with low hysteresis of the wild pansy (Viola tricolor) – new design principles for biomimetic materials

• Anna J. Schulte,
• Damian M. Droste,
• Kerstin Koch and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 228–236, doi:10.3762/bjnano.2.27

• characterized by micro papillae with cuticular folds on top. In contrast to the lotus surface with air pocket formation between cell papilla, wax crystals and salient water droplets [18], the petal surface seems to prevent air pocket formation and droplets penetrate into the cuticular folds by capillary forces

• °). Hydrophobic replicas of the Viola petals have a CA of 169° and a TA of <5°. These results show that finer folds arranged at small separation seem to prevent the penetration of water into the folds by capillary forces. Conclusion Flower petals provide a new design strategy for the development of

Moisture harvesting and water transport through specialized micro-structures on the integument of lizards

• Philipp Comanns,
• Christian Effertz,
• Florian Hischen,
• Konrad Staudt,
• Wolfgang Böhme and
• Werner Baumgartner

Beilstein J. Nanotechnol. 2011, 2, 204–214, doi:10.3762/bjnano.2.24

• condensation is improved by about 100%. The collected water is effectively transported by an interscalar capillary network towards the mouth of the lizards. The mouth serves as water sink so that water will be soaked from the whole body's surface by capillary forces. In the case of Phrynosoma cornutum, the

Capillary origami: superhydrophobic ribbon surfaces and liquid marbles

• Glen McHale,
• Michael I. Newton,
• Neil J. Shirtcliffe and
• Nicasio R. Geraldi

Beilstein J. Nanotechnol. 2011, 2, 145–151, doi:10.3762/bjnano.2.18

• , for an elastic substrate the rigidity depends on the cube of its thickness and so reduces rapidly as the substrate becomes thinner as it approaches becoming a thin sheet. In such circumstances, it has been shown that the capillary forces caused by a contacting droplet of a liquid can shape the solid

• forces during liquid evaporation and drying [6][7][8]. The effect of capillary forces due to nanodroplets in activating and guiding the folding of planar graphene ribbons has recently been simulated [9]. Figure 1 illustrates capillary origami concepts and effects based on original ideas by Py et al [3][4

• ]. When a PDMS (Sylgard 184) substrate of reduced thickness is contacted by a droplet of water (containing blue food dye) capillary forces bend it out of its initial planar shape (Figure 1a). When the substrate thickness is reduced to 45 μm and cut into a triangular shape (10 mm side lengths) and scored