Nanocrystalline TiO₂/SnO₂ heterostructures for gas sensing

• Barbara Lyson-Sypien,
• Anna Kusior,
• Mieczylaw Rekas,
• Jan Zukrowski,
• Marta Gajewska,
• Katarzyna Michalow-Mauke,
• Thomas Graule,
• Marta Radecka and
• Katarzyna Zakrzewska

Beilstein J. Nanotechnol. 2017, 8, 108–122, doi:10.3762/bjnano.8.12

• well known that oxygen vacancies act as water adsorption centers. Moreover, in the case of SnO2 water adsorption takes place because of the formation of weak van der Waals bonds between water dipoles and lattice ions (Sn4+ and O2−) [19]. This facilitates water desorption from the surface of SnO2-rich

Streptavidin-coated gold nanoparticles: critical role of oligonucleotides on stability and fractal aggregation

• Roberta D'Agata,
• Pasquale Palladino and
• Giuseppe Spoto

Beilstein J. Nanotechnol. 2017, 8, 1–11, doi:10.3762/bjnano.8.1

• that is polymer-depleted because of increased steric hindrance. Non-specific protein-DNA interactions are mediated by electrostatic interactions with the charged DNA backbone, hydrogen bonding, van der Waals forces and hydrophobic interactions [62][63][64]. The whole non-specific interaction can push

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

• situation where capillary forces would be absent. Additionally, since toe pads make close contact to surfaces, a role for van der Waals forces cannot be excluded [3]. However, little evidence was found for such forces in a recent AFM study of the toe pads of Litoria [24]. Capillary forces are highest when

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

• dependence can be expected if the decrease in lattice constant is driven by an energy minimization process. Attractive van-der-Waals forces between adjacent nanoparticles can cause agglomeration of nanoparticles, which we observed after removing the alkane ligands by UV/ozone treatment. However, van-der

• -Waals forces rather decrease slightly in a liquid medium in comparison to air. A slow compaction of the nanoparticle monolayer as we observed may be caused either by a collapse of alkyl tails or by partial interdigitation of alkyl tails between nanoparticles. The good solubility of 1-dodecanethiol in

Effect of Anderson localization on light emission from gold nanoparticle aggregates

• Mohamed H. Abdellatif,
• Marco Salerno,
• Gaser N. Abdelrasoul,
• Ioannis Liakos,
• Alice Scarpellini,
• Sergio Marras and
• Alberto Diaspro

Beilstein J. Nanotechnol. 2016, 7, 2013–2022, doi:10.3762/bjnano.7.192

• : where s is the interparticle distance and VT is the total interaction potential, which according to the classical model of DLVO theory [32][33] is made of is two parts [25]: where Velec is the electrostatic repulsion potential due to Coulomb force, and VVdW is the Van der Waals interaction potential

Morphology of SiO₂ films as a key factor in alignment of liquid crystals with negative dielectric anisotropy

• Volodymyr Tkachenko,
• Antigone Marino,
• Eva Otón,
• Noureddine Bennis and
• Josè Manuel Otón

Beilstein J. Nanotechnol. 2016, 7, 1743–1748, doi:10.3762/bjnano.7.167

• homeotropically, respectively. Such behavior can be explained by induced dipole–dipole interaction between LC and a smoothed oxide surface derived from van der Waals forces [3][8]. When α increases from 60° to 85°, the preferred orientation of LC with positive Δε switches from orthogonal to parallel to the plane

Scanning probe microscopy studies on the adsorption of selected molecular dyes on titania

• Jakub S. Prauzner-Bechcicki,
• Lukasz Zajac,
• Piotr Olszowski,
• Res Jöhr,
• Antoine Hinaut,
• Thilo Glatzel,
• Bartosz Such,
• Ernst Meyer and
• Marek Szymonski

Beilstein J. Nanotechnol. 2016, 7, 1642–1653, doi:10.3762/bjnano.7.156

• surface. The bonding between the first and second monolayers is of a weaker van der Waals type. Strong interactions of the molecules in the first layer with the substrate are unfavourable in possible solar cell applications [47]. However, the molecules in the second layer seem to be decoupled from the

Filled and empty states of Zn-TPP films deposited on Fe(001)-p(1×1)O

• Gianlorenzo Bussetti,
• Alberto Calloni,
• Rossella Yivlialin,
• Andrea Picone,
• Federico Bottegoni and
• Marco Finazzi

Beilstein J. Nanotechnol. 2016, 7, 1527–1531, doi:10.3762/bjnano.7.146

• limited to weak van der Waals forces [11]. Consequently, changes in the energy position of the different spectroscopic features of the 1 ML film with respect to the reference layer are usually interpreted in terms of intensity strength of the molecule–substrate interaction. In Figure 2, we report the

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

• (Figure 4a,b). In the latter case, it is presumably due to wetting reduction by the pad fluid (Figure 4c,d). Additionally, at the sites of solid–solid contact between insect pads and substrates, the true contact area and contribution of van der Waals forces are believed to be effectively reduced for both

Three-gradient regular solution model for simple liquids wetting complex surface topologies

• Sabine Akerboom,
• Marleen Kamperman and
• Frans A. M. Leermakers

Beilstein J. Nanotechnol. 2016, 7, 1377–1396, doi:10.3762/bjnano.7.129

• Very famous is the extension of the regular solution theory to the description of the L/V interface. In the footsteps of van der Waals [39] we like to find the density profile across a L/V interface φ(z). Here z is a (lattice) coordinate running perpendicular to the interface. We set z = 0 at the

• optimisation then leads to the famous tanh-profile already known by van der Waals. We do not go into these details and mention that fully in line with the numerical results presented in Figure 3B the scaling exponents as found by this analytical route are in line with the numerical results: For the surface

• the surface S. By means of a van der Waals loop the isotherm then returns to the binodal and approaches the infinite adsorbed amount upon the final approach towards the bulk binodal. We refer to this adsorbed amount as the “macroscopically thick film” on the surface. Such situation is typical for

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

• [14], and geckos, revealed in measurements with living animals [11] and with isolated setae [10]. This is particularly interesting since both types of adhesive systems (wet and dry) are supposed to be based on different physical interactions (capillarity versus van der Waals forces). For the dry

• 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

Fabrication and characterization of branched carbon nanostructures

• Sharali Malik,
• Yoshihiro Nemoto,
• Hongxuan Guo,
• Katsuhiko Ariga and
• Jonathan P. Hill

Beilstein J. Nanotechnol. 2016, 7, 1260–1266, doi:10.3762/bjnano.7.116

• load only the outermost layers of MWCNTs are involved as the relatively weak (van der Waals) bonding between the outer layers and the inner layers leads to slippage – the so called “sword in sheath” failure mechanism, which reduces the load-bearing capacity [1][7]. However, under compressive load this

Reasons and remedies for the agglomeration of multilayered graphene and carbon nanotubes in polymers

• Rasheed Atif and
• Fawad Inam

Beilstein J. Nanotechnol. 2016, 7, 1174–1196, doi:10.3762/bjnano.7.109

• dispersion state of filler as multilayered graphene (MLG) and carbon nanotubes (CNTs) tend to agglomerate due to van der Waals forces. The agglomeration can be avoided by using organic solvents, selecting suitable dispersion and production methods, and functionalizing the fillers. Another proposed method is

• nanocomposites and to gain knowledge about their biocompatibility and performance in living organisms. One of the main issues in the production of polymer nanocomposites is the dispersion state of fillers, because MLG and CNTs tend to agglomerate due to van der Waals forces. The agglomeration can be avoided by

• graphene sheets due to their coiled structure [18][19]. When an external load is applied, the graphene sheets undergo plastic deformation and a large amount of energy is absorbed [20]. Bending and folding takes place in graphene sheets and van der Waals interactions help to compensate the bending energy at

Optical absorption signature of a self-assembled dye monolayer on graphene

• Tessnim Sghaier,
• Sylvain Le Liepvre,
• Céline Fiorini,
• Ludovic Douillard and
• Fabrice Charra

Beilstein J. Nanotechnol. 2016, 7, 862–868, doi:10.3762/bjnano.7.78

• origins of such shifts are optical interactions between molecules or between molecules and the substrate and the deformation of molecules induced by van der Waals interactions between molecules and substrate. Intermolecular optical interactions are a consequence of the local electric field resulting from

Assembling semiconducting molecules by covalent attachment to a lamellar crystalline polymer substrate

• Rainhard Machatschek,
• Patrick Ortmann,
• Renate Reiter,
• Stefan Mecking and
• Günter Reiter

Beilstein J. Nanotechnol. 2016, 7, 784–798, doi:10.3762/bjnano.7.70

• particles to stack was much higher than for spherical particles, probably due to the larger area of contact between disk shaped particles resulting in a larger adhesive van der Waals energy. Thirdly, we found that the carboxyl groups on the surfaces of CPE45 nanocrystals were only partly accessible 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

• 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

Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

• Santiago D. Solares

Beilstein J. Nanotechnol. 2016, 7, 554–571, doi:10.3762/bjnano.7.49

• or dispersion (van der Waals) forces exerted by the probe, thus leading to a situation in which the sample is influenced by the measurement itself. One could continue extending the list of phenomena that preclude an ideal measurement by considering other issues such as limitations of the measurement

• [19]. Frequently, but not always, relatively large molecules are involved and their cohesive energy is governed by dispersion (van der Waals) and electrostatic forces, which are generally weaker than those generated by stretched covalent bonds or electrostatic interactions in ionic crystals, and which

• surface of the material, the total van der Waals force experienced by the tip depends on the geometry of that cavity, or more specifically, on the number of surface elements that are in close proximity to the tip surface [22]. This is why the maximum attractive force differs for the approach and retract

Rigid multipodal platforms for metal surfaces

• Michal Valášek,
• Marcin Lindner and
• Marcel Mayor

Beilstein J. Nanotechnol. 2016, 7, 374–405, doi:10.3762/bjnano.7.34

• substrate driven by van der Waals interactions. While delocalized π-systems are the ideal model compounds for numerous electronic and optical applications, a perpendicular arrangement with respect to the surface would be desired to profit from their properties. In optical experiments the quenching of

• length of alkyl legs is crucial for the molecular self-assembly indicates that the driving force for the surface arrangement is based on lateral van der Waals interactions of neighboring alkyl chains, similar to alkane thiols on gold. These results suggest that employing of long-chain alkylsulfanyl

• protruding from the surface. Moreover, the XPS analysis of the thermal stability of SAMs confirmed that the monolayer of the cyclohexyl platform with the longest alkyl chain 22-C13, is significantly more stable than the corresponding octadecylthiol SAM, which is attributed both to the strong lateral van der

Surface coating affects behavior of metallic nanoparticles in a biological environment

• Darija Domazet Jurašin,
• Marija Ćurlin,
• Ivona Capjak,
• Tea Crnković,
• Marija Lovrić,
• Michal Babič,
• Daniel Horák,
• Ivana Vinković Vrček and
• Srećko Gajović

Beilstein J. Nanotechnol. 2016, 7, 246–262, doi:10.3762/bjnano.7.23

• was agglomerated to clusters of about 600 nm (Table 1). Interestingly, PLL prevented a harsh agglomeration of SPIONs, but not of the AgNPs. It is known that NP coating agents can lose their stabilizing effect at high ionic strength due to complexation with counter ions. Consequently, van der Waals

Influence of calcium on ceramide-1-phosphate monolayers

• Joana S. L. Oliveira,
• Gerald Brezesinski,
• Alexandra Hill and
• Arne Gericke

Beilstein J. Nanotechnol. 2016, 7, 236–245, doi:10.3762/bjnano.7.22

• negatively charged head groups are responsible for the larger areas per molecule and larger tilt angles. Upon compression, the strong van der Waals forces between the acyl chains and the screening effect of sodium ions surpass the electrostatic repulsions allowing C1P to transform into the untilted state. On

• liquid-expanded phase (LE) due to repulsive forces between the negatively charged phosphate head groups. At pH 4, the C1P head groups are either one-fold deprotonated or neutral (most probably a mixture of protonation states). The strong van der Waals forces between the chains allow the system to be in a

• attractive van der Waals forces). This result supports the calcium-mediated interaction of C1P with the C2 domain of cPLa2α (effector protein). Since C1P is involved in many biological functions, its interaction with other ions could also be of interest. Furthermore, the potential to form solid-like domains

Characterisation of thin films of graphene–surfactant composites produced through a novel semi-automated method

• Nik J. Walch,
• Alexei Nabok,
• Frank Davis and
• Séamus P. J. Higson

Beilstein J. Nanotechnol. 2016, 7, 209–219, doi:10.3762/bjnano.7.19

• electrons in the graphene sheet, which only occurs when the proton is in close proximity (less than 5 Å) and involved in van der Waals interactions. This suggests that the hydrophobic chains of each surfactant lie flat against the graphene sheet with the exception of carbon-1 (the carbon attached directly

Synthesis and applications of carbon nanomaterials for energy generation and storage

• Marco Notarianni,
• Jinzhang Liu,
• Kristy Vernon and
• Nunzio Motta

Beilstein J. Nanotechnol. 2016, 7, 149–196, doi:10.3762/bjnano.7.17

• metal catalyst such as cobalt [48]. The nanotubes are typically bound together by strong van der Waals interactions and form tight bundles. The second method, laser ablation, uses continuous wave [49] or pulsed [50] lasers to ablate a carbon target in a 1200 °C tube furnace. A laser beam evaporates a

• acid [53]. In both the arc discharge and laser ablation methods, bundles of MWNTs and SWNTs held together by van der Waals forces are generated by the condensation of carbon atoms generated from the evaporation of solid carbon sources. The third method, chemical vapor deposition (CVD), involves the

• and can thus only be considered for research purposes. Chemical exfoliation. It is well known that the van der Waals forces that bond together the graphene sheets to form graphite are particularly weak and can be broken by external mechanical force. A common example of this can be seen with the usage

Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes

• Elena Dellacasa,
• Li Zhao,
• Gesheng Yang,
• Laura Pastorino and
• Gleb B. Sukhorukov

Beilstein J. Nanotechnol. 2016, 7, 81–90, doi:10.3762/bjnano.7.10

• polymers attract each other with van der Waals force, creating a more complementary and rigid structure, which leads to a higher melting point. In order to know whether the PDLA/PLLA complex had been formed after the PLA microcapsules were obtained, DSC was used to measure the melting points of four

Surface-site reactivity in small-molecule adsorption: A theoretical study of thiol binding on multi-coordinated gold clusters

• Elvis C. M. Ting,
• Tatiana Popa and
• Irina Paci

Beilstein J. Nanotechnol. 2016, 7, 53–61, doi:10.3762/bjnano.7.6

• 6 Å for the cutoff radius of the carbon PAO with the smallest ζ). A Grimme-type medium range van der Waals correction was included in the PBE-D2 calculations [76]. Dispersion coefficients and van der Waals radii for H, C, N, and S were taken from the original Grimme paper [76], and those for Au

• convolution of site reactivity and van der Waals attraction was found to determine the preference of methylthiolate to one or another binding site. As a result, adsorption was strongest at the kink sites (cf and fg), at edge sites where strong methyl-Au dispersive interactions could be established with the

• binding energies obtained using PBE without the van der Waals correction were also calculated and are provided in Table 2. As illustrated in the table, binding energies obtained using the pure PBE functional were weaker and much more homogeneous across the various binding sites. Whereas S–Au binding

Calculations of helium separation via uniform pores of stanene-based membranes

• Guoping Gao,
• Yan Jiao,
• Yalong Jiao,
• Fengxian Ma,
• Liangzhi Kou and
• Aijun Du

Beilstein J. Nanotechnol. 2015, 6, 2470–2476, doi:10.3762/bjnano.6.256

• package (VASP) [16][17]. The exchange-correlation interactions were described by a generalized gradient approximation (GGA) [18] with the Perdew–Burke–Ernzerhof (PBE) functional [19]. Spin-polarization and a damped van der Waals correction in Grimme’s scheme [20] were included in all the calculations. The