Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94

• semiconductors (Si, GaN, InP, InGaAs) provide a unique way to alter the properties of a surface at will. This ability may be manifested through a variety of phenomena, among which are wetting phenomena (hydrophobicity, hydrophilicity and oleophobicity), electronic phenomena (from affecting band bending and work

Template-assisted formation of microsized nanocrystalline CeO₂ tubes and their catalytic performance in the carboxylation of methanol

• Jörg J. Schneider,
• Meike Naumann,
• Christian Schäfer,
• Armin Brandner,
• Heiko J. Hofmann and
• Peter Claus

Beilstein J. Nanotechnol. 2011, 2, 776–784, doi:10.3762/bjnano.2.86

• overall ceramic yield was 10% and therefore significantly lower. This difference can be attributed to an enhanced wetting of the surface of the polymer fibres, as well as in the interstices between the packed PMMA fibre mats, during the impregnation step. This leads to a significantly enhanced wetting of

Approaches to nanostructure control and functionalizations of polymer@silica hybrid nanograss generated by biomimetic silica mineralization on a self-assembled polyamine layer

• Jian-Jun Yuan and
• Ren-Hua Jin

Beilstein J. Nanotechnol. 2011, 2, 760–773, doi:10.3762/bjnano.2.84

• exploited to functionalize the nanograss film with three representative species, namely porphyrin, Au nanoparticles and titania. Of particular note, the novel silica@titania composite nanograss surface demonstrated the ability to convert its wetting behavior between the extreme states (superhydrophobic

• on the preformed LPEI@silica nanograss surface, we were able to construct a smart silica@titania composite nanosurface that could switch its wetting behavior from superhydrophobic to superhydrophilic state under UV irradiation (black light, 10 mW/cm−2). As shown in Figure 10, the native silica

Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films

• Luyang Han,
• Ulf Wiedwald,
• Johannes Biskupek,
• Kai Fauth,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 473–485, doi:10.3762/bjnano.2.51

• annealing step resulted in a reduction of the average particle height. This decrease may arise from different processes, such as deformation due to increased substrate wetting, loss of Co atoms due to evaporation and bulk diffusion, or a combination of these processes. While the possibility of metal NPs

• wetting the metal substrate [26] is not excluded in this study, the TEM investigation (see below) clearly reveals a spherical particle shape before annealing and subsequent vanishing of particles after annealing (cf. Figure 7), favoring the model of Co atom loss. To estimate the degree of Co atom loss, we

Plasmonic nanostructures fabricated using nanosphere-lithography, soft-lithography and plasma etching

• Manuel R. Gonçalves,
• Taron Makaryan,
• Fabian Enderle,
• Stefan Wiedemann,
• Alfred Plettl,
• Othmar Marti and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 448–458, doi:10.3762/bjnano.2.49

• dried by nitrogen jet. The surfaces of the samples were submitted to an air plasma at primary vacuum for 10 s, in order to improve the wetting properties of the surface. Suspension volumes of 15 to 55 μL, depending on the size of the beads, were put on top of substrates and the samples were put inside

Dense lying self-organized GaAsSb quantum dots on GaAs for efficient lasers

• Thomas H. Loeber,
• Dirk Hoffmann and
• Henning Fouckhardt

Beilstein J. Nanotechnol. 2011, 2, 333–338, doi:10.3762/bjnano.2.39

• ]. These samples were grown at a temperature of T ≈ 500 °C. So far, photoluminescence (PL) signals of SK-grown GaSb QDs on GaAs have emerged at a wavelength between 1.0 and 1.3 µm [7][9]. The interface between the GaAs buffer and the GaSb QDs can cause a wetting layer, which will lead to an additional PL

• attributed to a possible wetting layer could not be identified. An electrically pumped QD laser was grown with an active region consisting of eight layers of QDs and an emission wavelength of λ ≈ 0.900 µm. Results and Discussion Growth procedure and dot characterization All samples were grown on (001) GaAs

• , relating to a wetting layer or otherwise, was observed. For a V/III ratio of 1/1 (smaller dots) the PL peak was at λ ≈ 0.887 μm for a growth temperature of T = 527 °C and a nominal coverage of 3 ML. The dots grown with a V/III ratio of 1.5/1 (larger dots) exhibited a PL peak at λ ≈ 1.035 μm and a smaller

Micro to nano: Surface size scale and superhydrophobicity

• Christian Dorrer and
• Jürgen Rühe

Beilstein J. Nanotechnol. 2011, 2, 327–332, doi:10.3762/bjnano.2.38

• size of the surface features reaches 1 μm. Keywords: contact angle; hysteresis; superhydrophobic; wetting; Introduction Superhydrophobic surfaces have recently been the focus of considerable scientific interest [1][2][3][4][5][6][7][8][9][10]. This is due to the fact that artificial superhydrophobic

• from a wetting situation (referred to as Cassie or composite wetting) where liquids no longer penetrate, but rest on top of the roughness features [1][2][11]. Air remains enclosed underneath, and drops are therefore supported by a “composite surface” that consists of solid and air (Figure 1a and 1b

• to suggest that, in particular, events taking place on the receding portions of the contact line play an important role [3][4][14]. Superhydrophobic wetting can be considered a special case of composite wetting. On a superhydrophobic material, the energy barriers associated with the motion of drops

Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film

• Sławomir Boncel,
• Krzysztof Z. Walczak and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2011, 2, 311–317, doi:10.3762/bjnano.2.36

• liquids and pristine CNTs was determined by dispersibility of randomly oriented and highly entangled, hydrophobic nanotubes. Wetting of CNTs in non-polar to medium polar liquids (a key factor enabling their dispersibility) can be gained generally via two routes: (1) By control of the CNTs dimensions

• and liquids was applied [19][20][21]. In order to verify critical parameters for wetting of HACNT films, we present here a simple and clear-cut approach. Our concept is based on a combination of thermodynamic and kinetic stipulation. The first parameter, the contact angle between HACNT film and the

• model, namely the Lucas–Washburn law. Results and Discussion With the aim of understanding the wetting behaviour of the HACNT film (5 × 106 nanotubes/mm2 dense, corresponding to an intertube separation of ~440 nm and free volume of 91%) (Figure 1), a series of experiments was performed in which the film

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

• leaves (petals) of many plants are superhydrophobic, but water droplets do not roll-off when the surfaces are tilted. On such surfaces water droplets are in the “Cassie impregnating wetting state”, which is also known as the “petal effect”. By analyzing the petal surfaces of different species, we

• discovered interesting new wetting characteristics of the surface of the flower of the wild pansy (Viola tricolor). This surface is superhydrophobic with a static contact angle of 169° and very low hysteresis, i.e., the petal effect does not exist and water droplets roll-off as from a lotus (Nelumbo nucifera

• –Baxter wetting state and roll-off at inclination angles below 5°. Fabricated hydrophobic polymer replicas of the wild pansy were prepared in an easy two-step moulding process and possess the same wetting characteristics as the original flowers. In this work we present a technical surface with a new

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

• integument of lizards that do perform moisture harvesting, the droplet hardly spreads as shown in Figure 3D for a specimen of the so called sandfish (Scincus scincus). Although the velocity of the water spreading varies slightly throughout the body, we found absolutely no correlation of the wetting behaviour

• and any macroscopic geometric parameter of the scales in the three investigated species (data not shown). Thus, either material properties or the micro ornamentation of the scales induce the high wettability. Contact angle and microscopic morphology To quantify the wetting properties we attempted to

• super hydrophilic. Interestingly, if the scale was completely dried in a desiccator containing silica gel before the experiment, the wetting was much less pronounced (Figure 4B). However, if the scale was completely immersed once and the experiment repeated, the same results as with the freshly removed

Superhydrophobicity in perfection: the outstanding properties of the lotus leaf

• Hans J. Ensikat,
• Petra Ditsche-Kuru,
• Christoph Neinhuis and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 152–161, doi:10.3762/bjnano.2.19

• drops touch only the highest papillae [12]. At higher pressures, e.g., at the impact of raindrops, the water intrudes deeper between the papillae (Figure 4a) and forms a meniscus at the still superhydrophobic wax tubules coating. The deformation of the non-wetting droplet surface due to surface tension

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

• Glen McHale Michael I. Newton Neil J. Shirtcliffe Nicasio R. Geraldi School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK 10.3762/bjnano.2.18 Abstract In the wetting of a solid by a liquid it is often assumed that the substrate is rigid. However

• ; superhydrophobic; Wenzel; Introduction In wetting, the usual implicit assumption is that a solid substrate is sufficiently thick or rigid, that it does not deform or change shape due to the interfacial forces that arise when it contacts a droplet of a liquid, however, in many natural systems this is not the case

• , in an absolute sense, be considered hydrophilic [11]. That work also discussed why for a partially wetting droplet to be observed there is necessarily an assumption of some rigidity of the substrate, so that the usual definition of relative hydrophobicity (and relative hydrophilicity) through contact

Superhydrophobic surfaces of the water bug Notonecta glauca: a model for friction reduction and air retention

• Petra Ditsche-Kuru,
• Erik S. Schneider,
• Jan-Erik Melskotte,
• Martin Brede,
• Alfred Leder and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 137–144, doi:10.3762/bjnano.2.17

• underlines the high relevance of the dense cover of surface protuberances previously assumed by Crisp in 1949 and proved by Balmert [24][33]. The wetting of the microtrichia cover will require a significant amount of energy due to the density of the structures. A dense cover of surface protuberances leads to

• hold an air film up to a fluid velocity of 5 m/s (Figure 5). The experiment started at low flow velocities of 0.5 m/s where no wetting was visible. At increasing flow velocities the fraction of the surface on the elytron covered with air decreased slightly (80% at 1.5 m/s). It is remarkable that at

• surface parameters, SEM images of 10 areas of each of the 6 investigated individuals were analysed with the digital image processing software ImageJ. Contact angle (CA) measurements. To characterise the wetting behaviour of the biological surfaces, contact (CA) and tilting angle (TA) measurements were

Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle–substrate chemistry and morphology, and of operating conditions

• Samer Darwich,
• Karine Mougin,
• Akshata Rao,
• Enrico Gnecco,
• Shrisudersan Jayaraman and
• Hamidou Haidara

Beilstein J. Nanotechnol. 2011, 2, 85–98, doi:10.3762/bjnano.2.10

• , the magnitude of friction and adhesion forces is strongly dependent on the capillary force that is related to the intrinsic wetting properties of the interfacial system. As a consequence, the resulting water meniscus (or layer) can either increase friction through increased adhesion in the contact

Biomimetics inspired surfaces for drag reduction and oleophobicity/philicity

• Bharat Bhushan

Beilstein J. Nanotechnol. 2011, 2, 66–84, doi:10.3762/bjnano.2.9

• created, and in this article the influence of structure on drag reduction efficiency is reviewed. Biomimetic-inspired oleophobic surfaces can be used to prevent contamination of the underwater parts of ships by biological and organic contaminants, including oil. The article also reviews the wetting

• that can be used against marine ship fouling [17]. Jung and Bhushan [20] proposed a model for predicting the oleophobic/philic nature of surfaces and showed how the water and oil droplets in three phase interfaces influence the wetting behavior on micropatterned surfaces with varying pitch values as

• applications. In this section, we discuss a model for predicting the oleophobic/philic nature and experimental measurements of the wetting properties of the surfaces. Modeling of contact angle for various interfaces If a water droplet is placed on a solid surface in air, the solid–air and water–air interfaces

Kinetic lattice Monte-Carlo simulations on the ordering kinetics of free and supported FePt L1₀-nanoparticles

• Michael Müller and
• Karsten Albe

Beilstein J. Nanotechnol. 2011, 2, 40–46, doi:10.3762/bjnano.2.5

• species to the interface. In cases where wetting of the substrate or surface facetting occurs, we find that diffusional atomic motion on the surface goes along with an enhanced long-range order. Keywords: FePt; Monte-Carlo simulations; nanoparticles; ordering kinetics; Introduction Nanoparticles in

• cases are considered: First, the relative strength of the interactions of the substrate is assumed to be identical for both elements. In this case, the parameters determine the wetting angle of the particle in equilibrium with the substrate. Second, it is assumed that only Pt has a significant binding

• energy to the substrate, with and . In addition to wetting, the parameters then provide a driving force for segregation of Pt at the interface to the substrate which prefers a c-axis orientation of the L10 structure perpendicular to the substrate. For generating the initial configuration for kinetic

Single-pass Kelvin force microscopy and dC/dZ measurements in the intermittent contact: applications to polymer materials

• Sergei Magonov and
• John Alexander

Beilstein J. Nanotechnol. 2011, 2, 15–27, doi:10.3762/bjnano.2.2

• hydrophobic surface of PS-enriched domains. The droplets are characterized by a relatively large wetting angle that indicates hydrophobicity of the underlying locations. Compared to surface potential studies the use of dC/dZ measurements was relatively limited by studies of organic layers [23] and water

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

• Ulf Wiedwald,
• Luyang Han,
• Johannes Biskupek,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 24–47, doi:10.3762/bjnano.1.5