26.07.21 Article on "How water wets and self-hydrophilizes nanopatterns of physisorbed hydrocarbons" published in the Journal of Colloids and Interface Science.
We present experiments and computer simulations on the wetting behaviour of water on molecularly thin, self-assembled alkane carpets of dotriacontane (n-C32H66 or C32) physisorbed on the hydrophilic native oxide layer of silicon surfaces during dip-coating from a binary alkane solution. By changing the dip-coating velocity we control the initial C32 surface coverage and achieve distinct film morphologies, encompassing homogeneous coatings with self-organised nanopatterns that range from dendritic nano-islands to stripes. These patterns exhibit a good water wettability even though the carpets are initially prepared with a high coverage of hydrophobic alkane molecules. Using in-liquid atomic force microscopy, along with molecular dynamics simulations, we trace this to a rearrangement of the alkane layers upon contact with water. Water molecules displace to a large extent the first adsorbed alkane monolayer and thereby reduce the hydrophobic C32 surface coverage. Thus, our experiments evidence that water molecules can very effectively hydrophilize initially hydrophobic surfaces that consist of weakly bound hydrocarbon carpets.
14.06.2021 Nanostructuring of materials leads to completely new, often surprising properties; this makes them highly interesting for new fields of application and technologies. However, whether these materials can be processed into robust components and thus find their way into applications depends very much on their mechanical properties. These are usually particularly difficult to determine without changing them through the measuring process or even destroying the materials. Within a German-French research team we have now developed a non-contact and non-destructive measurement method using laser ultrasound in such a way that the elastic properties of nanostructured materials can be characterised in detail. The results are reported in an article entitled "Laser-excited elastic guided waves reveal the complex mechanics of nanoporous silicon" in the journal Nature Communications (see also the DESY/TUHH press release: German/English).
11.05.2021 The article "Synergistic and Competitive Adsorption of Hydrophilic Nanoparticles and Oil-Soluble Surfactants at the Oil–Water Interface" has been published in Langmuir. An illustration from the article is featured on the cover of the current Langmuir issue.
10.05.2021 Lars Dammann's PhD project featured - The PhD project of Lars Damman on "Water and Hydrocarbons in Confined Geometries: Correlating High Resolution X-Ray Diffraction with Molecular Dynamics Simulation" within DASHH is featured by the Helmholtz Association, see here.
25.02.2021 Sustainable harvesting of electrical energy with nanoporous materials - Can phase transitions of water in nanopores be used to generate electrical energy on a larger scale? This is what we, within an international team of researchers, will be investigating in the European Union-funded research project "Energy harvesting via wetting/drying cycles with nanoporous electrodes (EHAWEDRY)", see additional details here (English/German).
09.02.2021 Second-order nonlinear optics, in particular Second-Harmonic Generation (SHG) is the base for a large variety of devices aimed at the active manipulation of light. Within an European collaboration we demonstrate that embedding chromophores in conical silica nanopores results in a photonic metamaterial exhibiting SHG, see the article entitled "Anisotropic confinement of chromophores induces second-order nonlinear optics in a nanoporous photonic metamaterial", published in Optics Letters.
