Hexakis(n-alkyloxy)triphenylene) (HATn) consisting of an aromatic triphenylene core and alkyl side chains are model discotic liquid crystal (DLC) systems forming a columnar mesophase. In the mesophase, the molecules of HATn self-assemble in columns, which has one-dimensional high charge carrier mobility along the columns. Here, a homologous series of HATn with different length of the alkyl...
Liquid crystalline mesophases in nanoconfinement exhibit intriguing phase transition behaviors and relaxation dynamics. Here in, we investigate the molecular dynamics and electrical conductivity of a linear shaped guanidinium based ILC confined in self-ordered nano porous alumina oxide membranes of pore size ranging from 180nm down to 25nm by employing broadband dielectric spectroscopy (BDS)...
Ionic liquids (ILs) have been widely used in a range of applications due to their unique physicochemical and electrochemical properties. For many of their practical applications, for example, in mechanical devices, supercapacitors, batteries, and catalytic reactors, etc., understanding the properties of ILs close to a solid surface or in confinement has crucial importance. Some protic and...
The investigation of the processes taking place at the solid/aqueous solution interface in nanoconfinement media is an important key parameter to understand and predict the behavior of nanoporous materials. Indeed, understanding the water and ions behavior in such media can help to clarify the processes and chemical reactions occurring at this level of confinement. Recently, we highlighted how...
γ-Alumina is a widely used heterogeneous catalytic support. To perfect the optimization of its catalytic performance, the accessibility of the molecules to active sites and more generally the molecular transport inside the support need to be fully assessed. As γ-alumina is obtained through a topotactic transformation, most of its properties are inherited by the boehmite and its process [1]....
With their strong confining porosity and versatile surface chemistry, Zeolitic Imidazolate Frameworks - including the prototypical ZIF-8 - display exceptional properties for various applications. In particular, the forced intrusion of water at high pressure (around 25 MPa) into ZIF-8 nanopores is of interest for energy storage. Such a system reveals also ideal to study experimentally water...
Diffusion of tracer dye molecules in water confined to nanoscale is an important subject with a direct bearing on many technological applications. It is not yet clear however, if the dynamics of water in hydrophilic as well as hydrophobic nanochannels remains bulk-like. Here, we present diffusion measurement of a fluorescent dye molecule in water confined to nanoscale between two...
The effect of surface conditions on the glass-transition dynamics of poly(phenylmethylsiloxane) confined in cylindrical nanopores
Karolina Adrjanowicz, Roksana Winkler, Institute of Physics, University of Silesia, Poland, email. kadrjano@us.edu.pl
Lukasz Laskowski, Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
In this contribution, we demonstrate the results of...
Block copolymer self-assembly provides effective routes for the precise structural arrangement of inorganic materials architectures, either via templating or co-assembly. In my talk, I want to provide an overview of how we exploit formation principles in 2D and 3D to tailor mesostructured electrodes for biosensing applications.
We have recently developed an approach, based on quartz crystal...
In this work we show the power of the off-specular scattering (OSS) technique applied simultane-ously with the specular reflection (SR) to probe the thermal capillary-type wave spectrum of buried interfaces between immiscible polymer layers. The combined SR and OSS data analysis performed using a quick and robust originally developed algorithm, includes a common absolute scale normal-ization of...
Nanoparticles can be utilized to induce restricted spatial mobility in the polymer and smaller molecules. However, a simple blend of nanoparticles with the organic molecules leads to phase separation and hence is unsustainable. Grafting the molecules on nanoparticle surface addresses this problem efficiently. The grafting induces significant alteration to the conformation and dynamics of the...
An emblematic case of nanofluidics is the ultra-low friction of water in hydrophobic carbon nanotubes. But original behaviours of water molecules are also observed in hydrophilic nanotubes, such as imogolite nanotubes (INT), with nominal composition GeAl$_2$O$_7$H$_4$ and SiAl$_2$O$_7$H$_4$, noted Ge-INT and Si-INT. Inner diameter is 2.9nm for Ge-INT and 1.5nm for Si-INT. Investigations are...
Clays are porous lamellar materials with remarkable properties of adsorption and retention, which make them good candidates for environmental applications such as water pollution control or waste storage (radioactive, CO2). The retention properties of the mobile species are strongly influenced by the behavior of water in the medium.
On one hand, classical molecular simulations make it...
In February 2022, the Intergovernmental Panel on Climate Change (IPCC) report has been published by the UNO, which stated the critical situation and the environmental emergency to reduce greenhouse gases emissions to keep the global warmth below 1.5°C. Thus, an effort has to be made to be able to harvest energy with a minimal CO2 emission. Nanofluidics (fluidic transport in nanoconfined...
Understanding transport and behavior of ionic solutions in single-digit nanoconfinement is crucial to explain the behavioral transition of confined solutions. This is particularly the case when the system length scale crosses the classical key length scales describing energetics and equilibrium of ionic solutions next to surfaces. Experimentally probing nanoconfinement would open large...
Ion conducting polymer membranes are designed for applications ranging from separation and dialysis, to energy conversion and storage technologies. A key application is in fuel cells, where the semi-permeable polymer membrane plays several roles. In a fuel cell, the polymer membrane permits the selective transport of H+ or OH- to enable completion of the electrode half-reactions, plays a major...
Ion-exchange separator membranes (IEM) in electrochemical energy conversion and storage devices need to conduct a specific type of ion for mediating the electrochemical reactions taking place at anode and cathode while efficiently separating the electrochemically active species. In PEM-fuel cells and electrolyzers and in flow batteries, the conducting ions are mostly H$^+$ or OH$^-$, and...
The wetting and drying cycles of salt solutions confined in conductive nanoporous electrodes are conceived to generate energy from low-grade waste heat by coupling the pore drying/wetting process with the charging/ discharging cycles of the electrodes. This could be realised by ascertaining the optimal physical conditions that allow a systematic control and manipulation of the electrically...
Water is the solvent of choice whenever hydrophilic substances are involved in a chemical process. However, because of its polar nature, the solubility of non-polar compounds in water is limited. The modulation of water's solvent properties to increase the solubility of non-polar molecules [1] would be ideal for phasing out the necessity of (organic) environmentally unfriendly solvents in the...
The nonequilibrium dynamics of linear and star-shaped cis-1,4 polyisoprenes confined within nanoporous alumina was explored as a function of pore size, d, molar mass and functionality (f = 2, 6, 64).$^{1,2}$ Two thermal protocols were tested; one resembling a quasi-static process (I), and another involving fast cooling followed by annealing (II). Although both protocols give identical...
Carbon nanostructured materials are regarded to have high potential for the storage and management of H2 at cryogenic temperatures. We have observed isothermal large hysteretic hydrogen adsorption in samples made out of Double Wall Carbon Nanotubes bundles at 50 K, 77 K and 150 K and up to 15 bar of pressure. Adsorption metastability opens remarkable possibilities: it can be used to lower the...
We report a complete neutron scattering investigation of the structure and dynamics of monomer and polymer phases of C$_{60}$ carbon peapods. When the temperature is lowered below 300 K, the temperature evolution of the monomer data reflects a continuous increase of the orientational correlations between adjacent molecules, a signature of the strong rotation-translation coupling in this...
The global climate challenges require a rapid suppression of fossil fuel use. Batteries are now widely used to replace petrol in cars, but they still have many disadvantages in terms of elevated price, long charging time, use of rare chemical elements and recycling. Therefore, hydrogen is still considered an important energy carrier for future mobile applications and much recent research...
The rate at which a nonequilibrium system decreases its free energy is commonly ascribed to molecular relaxation processes, arising from spontaneous rearrangements at the microscopic scale. While equilibration of liquids usually requires density fluctuations at timescales quickly diverging upon cooling – known as the $\alpha$-modes –, growing experimental evidence indicates the presence of...
Quasi-two-dimensional (quasi-2D) colloidal hard-sphere suspensions confined in a slit geometry are widely used as two-dimensional (2D) model systems in experiments that probe the glassy relaxation dynamics of 2D systems. However, the question of to what extent these quasi-2D systems indeed represent 2D systems is rarely brought up. Here, we use computer simulations that take into account...
Due to the large surface energy reduction linked to the adsorption of colloids at a fluid interface, these micrometer particles are often used as stabilizing units in the formation of highly stable complex interfacial fluids, Pickering emulsions, foams and colloidosomes. In addition, they act as probes in the characterization of interfacial microrheological properties or as model systems in...
Atomic vibrations play a vital role in the functions of various physical, chemical, and biological materials. The vibrational properties and the specific heat of a bulk material are well described by the Debye theory, which successfully predicts the quadratic w^2 low-frequency scaling of the vibrational density of states (VDOS) in bulk solids from few fundamental assumptions. However, the...
The interior of biological cells corresponds to an environment, which is highly crowded. For instance, the total concentration of protein and RNA inside Escherichia coli is in the range 300−400 mg/mL [1]. Crowding can induce the confinement of molecular motions due to the restrictions in space. It is established that diffusion rates [2], but also activities, dynamics, aggregation or protein...
Beryl crystals contain structural voids which may be partly occupied by single molecules of water. Due to the local symmetry of the atoms around the voids, the molecules experience sets of potential minima with respect to their angular orientations. The molecules remain fairly independent of the neutral crystal lattice, and they are mutually separated by several Å. Thus, they cannot...
We provide an exhaustive characterization of structural properties and nuclear dynamics in tungstic acid (WO3·H2O). To this end, we employ Neutron and X-ray Diffraction (ND and XRD) combined with Inelastic Neutron Scattering (INS) and Neutron Compton Scattering (NCS) experiments, and corroborate the analysis with extensive ab initio modelling. The first step in our analysis is the...
Endofullerenes are supramolecular complexes where one small (endohedral) atom/molecule is completely confined within a bigger, fullerene, molecule which acts as an enclosing cage.1 Endofullerenes offer an ideal “particle in a box” nano-laboratory to observe quantum mechanical phenomena.
The noble gas endofullerenes He@C₆₀ and Ne@C₆₀ have been investigated using INS (Inelastic Neutron...
Endofullerenes are substances in which small molecules or atoms are encapsulated in highly symmetrical cages of carbon atoms. Each encapsulated atom or molecule behaves as a textbook ex-ample of a quantized particle-in-a-box. The newest and largest member of the endofullerene fami-ly tree, namely CH$_{4}$@C$_{60}$, is the first organic molecule trapped inside the cage and the main interest of...
Natural methane hydrates are estimated to be the largest source of unexploited hydrocarbon fuel. The ideal conditions for methane hydrate formation are low temperatures and high pressures. On the other hand, recent experimental studies suggest that porous materials, thanks to their confinement effects, can enable methane hydrate formation at milder conditions, although there has not been a...
