Porous membranes built up from hydrophilic poly(ionic liquid)s

Porous polymer membranes via electrostatic complexation triggered by neutralization are fabricated for the first time from a water-soluble poly(ionic liquid) (PIL). The porous structure is formed as a consequence of simultaneous phase separation of the PIL and ionic complexation, which occurred in a basic solution of a non-solvent for the PIL. These membranes have a stimuli-responsive porosity, with open and closed pores in isopropanol and in water, respectively. This property is quantitatively demonstrated in filtration experiments, where water is passing much slower through the membranes than isopropanol.Comment: 13 pages, 3 figure

Roughness gradient induced spontaneous motion of droplets on hydrophobic surfaces: A lattice Boltzmann study

The effect of a step wise change in the pillar density on the dynamics of droplets is investigated via three-dimensional lattice Boltzmann simulations. For the same pillar density gradient but different pillar arrangements, both motion over the gradient zone as well as complete arrest are observed. In the moving case, the droplet velocity scales approximately linearly with the texture gradient. A simple model is provided reproducing the observed linear behavior. The model also predicts a linear dependence of droplet velocity on surface tension. This prediction is clearly confirmed via our computer simulations for a wide range of surface tensions.Comment: 6 pages, 8 figure

Non-additivity of pair interactions in charged colloids

It is general wisdom that the pair potential of charged colloids in a liquid may be closely approximated by a Yukawa interaction, as predicted by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. We experimentally determine the effective forces in a binary mixture of like-charged particles, of species 1 and 2, with blinking optical tweezers. The measured forces are consistent with a Yukawa pair potential but the (12) cross-interaction is not equal to the geometric mean of the (11) and (22) like-interactions, as expected from DLVO. The deviation is a function of the electrostatic screening length and the size ratio, with the cross-interaction measured being consistently weaker than DLVO predictions. The corresponding non-additivity parameter is negative and grows in magnitude with increased size asymmetry.Comment: Final versio

Attractive interaction between ions inside a quantum plasma structure

We construct the model of a quantum spherically symmetric plasma structure based on radial oscillations of ions. We suppose that ions are involved in ion-acoustic plasma oscillations. We find the exact solution of the Schr\"{o}dinger equation for an ion moving in the self-consistent oscillatory potential of an ion-acoustic wave. The system of ions is secondly quantized and its ground state is constructed. Then we consider the interaction between ions by the exchange of an acoustic wave. It is shown that this interaction can be attractive. We describe the formation of pairs of ions inside a plasma structure and demonstrate that such a plasmoid can exist in a dense astrophysical medium corresponding to the outer core of a neutron star.Comment: 17 pages, two columns, 3 figures, PDF LaTeX; paper was significantly revised, Appendix was shortened, new astrophysical application was discussed; version accepted for publication in J. Plasma Phy

Confined Multilamellae Prefer Cylindrical Morphology

By evaporating a drop of lipid dispersion we generate the myelin morphology often seen in dissolving surfactant powders. We explain these puzzling nonequilibrium structures using a geometric argument: The bilayer repeat spacing increases and thus the repulsion between bilayers decreases when a multilamellar disk is converted into a myelin without gain or loss of material and with number of bilayers unchanged. Sufficient reduction in bilayer repulsion can compensate for the cost in curvature energy, leading to a net stability of the myelin structure. A numerical estimate predicts the degree of dehydration required to favor myelin structures over flat lamellae.Comment: 6 pages, 3 figures, submitted to Euro. Phys. J.

From Intramolecular (Circular) in an Isolated Molecule to Intermolecular Hole Delocalization in a Two‐Dimensional Solid‐State Assembly: The Case of Pillarene

To achieve long‐range charge transport/separation and, in turn, bolster the efficiency of modern photovoltaic devices, new molecular scaffolds are needed that can self‐assemble in two‐dimensional (2D) arrays while maintaining both intra‐ and intermolecular electronic coupling. In an isolated molecule of pillarene, a single hole delocalizes intramolecularly via hopping amongst the circularly arrayed hydroquinone ether rings. The crystallization of pillarene cation radical produces a 2D self‐assembly with three intermolecular dimeric (sandwich‐like) contacts. Surprisingly, each pillarene in the crystal lattice bears a fractional formal charge of +1.5. This unusual stoichiometry of oxidized pillarene in crystals arises from effective charge distribution within the 2D array via an interplay of intra‐ and intermolecular electronic couplings. This important finding is expected to help advance the rational design of efficient solid‐state materials for long‐range charge transfer

Mass Transfer Model for Basic Blue Adsorption onto Pillared Bentonite Clay Using Langmuir Equilibrium and Taking into Account the Intra Particle Concentration Gradient

Bentonite clay from Pacitan, East Java, was made using intercalation and pil/arization method. using cationic surfactant HDTMA-Cl as intercalating agent and NaOH-AICI; mixture with OHIAI ratio was 0,8 as pi/loring agent at BrfC. Furthermore, calcination was done at 50rfC for 4 hours. Adsorption process was done at laboratory scale batch :.ystem with initial Basic Blue 41 dye concentration varied between 100 ppm, 200 ppm, 300 ppm, 400 ppm,and 500 ppm for adsorbent mass ratio was 0, I giL and adsorbent size of 100 mesh. Adsorbent mass ratio was varied 0,/ giL; 0,2 giL; 0,25 giL; 0,35 giL; and 0,4 giL for initial dye concentration of 600 ppm. Adsorption equilibrium was analyzed using Langmuir equilibrium model, and kinetic model was developed with considering convection mass transfer at adsorbent surface and intra-particle dye diffusion. Mathematic model and experimental data was used to calculate dye convective mass transfer and effective diffusion coefficient using computer program. The result showed that Basic Blue 41 -pil/arizedbentonite clay equilibrium obeyed Langmuir equilibrium model. Developed kinetic model was relatively fitted to experimental data. Maximum dye removal was 97.947 %. Generally, Basic Blue 41 adsorption kinetic was controlled by film resistance at adsorbent surface and intra-particle diffusion resistance

Macroporous materials: microfluidic fabrication, functionalization and applications

This article provides an up-to-date highly comprehensive overview (594 references) on the state of the art of the synthesis and design of macroporous materials using microfluidics and their applications in different fields

Stable covalently photo-cross-linked poly(ionic liquid) membrane with gradient pore size

An imidazolium-based poly(ionic liquid) is covalently cross-linked via UV light-induced thiolene (click) chemistry to yield a stable porous polyelectrolyte membrane with gradients of crosslink density and pore size distribution along its cross-section.Comment: 16 pages, 10 figure