arXiv subjects

T. Staszewski

Publications and source records attributed to T. Staszewski.

6 recordsLinked to original sources

arXiv2026

Surfactant solutions confined in homogeneous and Janus-like slits

We study the behavior of aqueous surfactant solutions in the bulk phase and in slit-like pores by molecular dynamics. Adsorption and self-assembly of nonionic surfactants C$_7$E$_3$ that mimic alkyl poly(ethylene oxide) molecules are investigated. We consider pores with the same walls and Janus-like slits. The individual walls are inert, hydrophilic, or hydrophobic. We focus on the morphology of the surfactant solution confined in different slits. The influence of a pore type and its width is discussed. The aggregative adsorption of surfactants was found. Our simulations show that in slits surfactants assemble into structures that do not occur in the bulk phases.

cond-mat.soft↗

arXiv2024

Shape changes of a single hairy particle with mobile ligands at a liquid-liquid interface

We investigate rearrangements of a single hairy particle at a liquid-liquid interface using coarse-grained molecular dynamics simulations. We consider the particles with the same (symmetrical interactions) and different (asymmetrical interactions) affinity to the liquids. We show how ligand mobility affects the behavior of the hairy particle at the liquid-liquid interface. We found that such a hairy particle can take various shapes at the interface. For example, a Janus-like snowman consisting of a segment cluster and a bare part of the core, Saturn-like structures, and the core with a wide ``plume'' on one side. A configuration of the particle at the interface is characterized by the vertical displacement distance and the orientation of the particle relative to the phase boundary. The selected descriptors are used to characterize the shape of the segment cloud. We found that the shape of a particle and its localization at the interface can be determined by tuning the interactions with the liquids.

cond-mat.soft↗

arXiv2022

A polymer-tethered particle confined in a slit

Shape transformations of hairy nanoparticles under confinement are studied using molecular dynamic simulations. We discuss the behavior of these particles in slits with inert or attractive walls. We assume that only chain-wall interactions are attractive. The impact of the strength of interactions with the walls and the width of the slits on the particle configuration is shown. In the case of attractive surfaces, we found new structures in which the chains are connected with both walls and form bridges between them: pillars, symmetrical and asymmetrical spools, and hourglasses. In wide pores with strongly attractive walls, hairy particles adsorb on one of the surfaces and form "mounds" or starfish-like strucures.

cond-mat.soft↗

arXiv2016

Ordering and order-disorder phase transition in the (1x1) monolayer chemisorbed on the (111) face of an fcc crystal

In this paper we have considered a simple lattice gas model of chemisorbed monolayer which allows for the harmonic fluctuations of the bond length between the adsorbate atom and the surface site. The model also involves a short-ranged attractive potential acting between the adsorbed atoms as well as the surface periodic corrugation potential. It has been assumed that the adsorbed atoms are bonded to the uppermost layer of the substrate atoms. In particular, using Monte Carlo simulation method we have focused on the orderings appearing in the dense monolayer formed on the (111) face of an fcc solid. Within the lattice gas limit, the chemisorbed layer forms a (1x1) structure. On the other hand, when the bonds are allowed to fluctuate, three other different ordered phases have been found to be stable in the ground state. One of them has been found to be stable at finite temperatures and to undergo a phase transition to the disordered state. The remaining two ordered states have been found to be stable in the ground state only. At finite temperatures, the ordering has been demonstrated to be destroyed due to large entropic effects.

cond-mat.mes-hall↗

arXiv2016

Adsorption from binary solutions on chemically bonded phases

We use density functional theory to investigate adsorption of liquid mixtures on solid surfaces modified with end-grafted chains. The chains are modelled as freely joined spheres. The fluid molecules are spherical. All spherical species interact via the Lennard-Jones (12-6) potential. The Lennard-Jones (9-3) potential describes interactions of solvent molecules with the substrate. We study the relative excess adsorption isotherms, the structure of surface layer and its composition. The impact of the following parameters on adsorption is discussed: the grafting density, the grafted chain length, interactions of solvent molecules with grafted chains and with the substrate, and the presence of active groups in grafted chains. The theoretical results are consistent with experimental observations.

cond-mat.soft↗

arXiv2012

A density functional study of the structure of tethered chains in a binary mixture

A density functional study of the structure of a layer formed by chain molecules pinned to a solid surface is presented. The chains are modeled as freely joined spheres. Segments and all components interact via Lennard-Jones (12-6) potential. The interactions of fluid molecules with the wall are described by the Lennard-Jones (9-3) potential. We analyze how different parameters of the model affect the dependence of the brush height upon the mixture composition. We consider the effect of grafting density and the parameters characterizing the interactions of fluid molecules with the substrate and with the chains as well as interactions within the mixture. The changes in the brush height correlate with the adsorption of particular components.

cond-mat.soft↗