Role of EDTA protonation in chelation-based removal of mercury ions from water.

A robust method of hazardous metal ion removal from an aqueous environment involves the use of chelating agents, such as ethylenediaminetetraacetic acid (EDTA). Here, we focus on mercury (Hg) uptake by EDTA using both molecular dynamics and density functional theory simulations. Our results indicate that the deprotonation of the EDTA carboxylate groups improves the localization of negative charge on the deprotonated sites.

Reversible Binding Interfaces Made of Microstructured Polymer Brushes.

The polymer brush architecture of the end-tethered polymer molecules is one of the most widely used efficient methods to regulate interfacial interactions in colloidal systems found in live matter and manufactured materials. Emerging applications of polymer brush structures require solutions to new tasks in the control of interfacial interactions. The rapid development of live cell manufacturing relies on scalable and efficient cell harvesting methods.

Modeling of the photo-induced stress in azobenzene polymers by combining theory and computer simulations.

It has been shown recently that the photo-induced deformations in azobenzene-containing polymers of a side-chain architecture can be explained by means of the so-called orientational approach. The explanation is based on the following sequence of steps: (i) reorientation of azobenzenes under illumination, (ii) reorientation of the polymer backbones coupled mechanically to azobenzenes, and (iii) development of large stress in a material. Step (i) is based on the angle selective absorption of the azobenzene chromophore, which is a well established fact.

Biofouling-Resistant Porous Membranes with a Precisely Adjustable Pore Diameter via 3D Polymer Grafting.

A facile route to biofouling-resistant porous thin-film membranes that can be fine-tuned for specific needs in diverse bioseparation, mass flow control, sensors, and drug delivery applications is reported. The proposed approach is based on combining two distinct macromolecular systems-a cross-linked poly(2-vinyl pyridine) network and a 3D-grafted polyethylene oxide (PEO) layer-in one robust porous material whose porosity can be adjusted within a wide range, covering the macroporous and mesoporous size regimes. Notably, this reconfigurable material maintains its antifouling properties throughout the entire range of pore size configurations because of a dense surface carpet of PEO chains with self-healing properties that are immobilized both onto the surface and inside the polymer network through what was termed 3D grafting.

Gelation of patchy ligand shell nanoparticles decorated by liquid-crystalline ligands: computer simulation study.

We consider the coarse-grained modelling of patchy ligand shell nanoparticles with liquid crystalline ligands. The cases of two, three, four and six symmetrically arranged patches of ligands are discussed, as well as the cases of their equatorial and icosahedral arrangement. A solution of decorated nanoparticles is considered within a slit-like pore with solid walls and the interior filled by a polar solvent.

Photoisomerization Kinetics and Mechanical Stress in Azobenzene-Containing Materials.

Kinetics of photoisomerization and time evolution of ordering in azobenzene-containing materials are studied theoretically and by using computer simulations. Starting from kinetic equations of photoisomerization, we show that the influence of light is equivalent to the action of the effective potential, which reorients chromophores perpendicularly to polarization direction. The strength of the potential is defined by optical and viscous characteristics of the material.

Reorientation Dynamics of Chromophores in Photosensitive Polymers by Means of Coarse-Grained Modeling.

We study the photoisomerization of azobenzene chromophores embedded into a polymer matrix by using coarse-grained simulations. Two types of beads are considered: t- and c-beads, which are rich in trans and cis isomers, respectively. Simulations combine deterministic (molecular dynamics) and stochastic (random-type switching) parts.

Topological defects around a spherical nanoparticle in nematic liquid crystal: coarse-grained molecular dynamics simulations.

We consider the applicability of coarse-grained molecular dynamics for the simulation of defects in a nematic liquid crystal around a colloidal particle. Two types of colloids are considered, a soft colloid resembling a liquid crystal dendrimer or a similar macromolecule. In addition, a decorated colloid is used which could represent a gold nanoparticle with mesogen-modified surface.

Opposite photo-induced deformations in azobenzene-containing polymers with different molecular architecture: molecular dynamics study.

Photo-induced deformations in azobenzene-containing polymers (azo-polymers) are central to a number of applications, such as optical storage and fabrication of diffractive elements. The microscopic nature of the underlying opto-mechanical coupling is yet not clear. In this study, we address the experimental finding that the scenario of the effects depends on molecular architecture of the used azo-polymer.

Nanostructures in a binary mixture confined in slit-like pores with walls decorated with tethered polymer brushes in the form of stripes: dissipative particle dynamics study.

Using dissipative particle dynamics, we investigate the behavior of a binary mixture, exhibiting demixing in a bulk phase, confined in slit-like pores with walls modified by the stripes of tethered brush of chains. Our main interest is to determine possible morphologies that can be formed inside the pore, depending on the geometrical parameters characterizing the system (the size of the pore and the width of the stripes). In order to describe the observed morphologies we calculate several characteristics, as the density and local temperature profiles, the radii of gyration for the attached polymers, and the minimum polymer-polymer distances in the direction parallel and perpendicular to the pore walls.

Structure and internal dynamics of a side chain liquid crystalline polymer in various phases by molecular dynamics simulations: a step towards coarse graining.

Side chain liquid crystalline polymer with relatively long spacer was modeled on a semiatomistic level and studied in different liquid crystalline phases with the aid of molecular dynamics simulations. Well equilibrated isotropic, polydomain smectic and monodomain smectic phases were studied for their structural and dynamic properties. Particular emphasis was given to the analysis on a coarse-grained level, where backbones, side chains, and mesogens were considered in terms of their equivalent ellipsoids.