Publications (189)387.74 Total impact
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ABSTRACT: We investigate the electric double layer formed between charged walls of a slitlike pore and a solvent primitive model (SPM) for electrolyte solution. The recently developed version of the weighted density functional approach for electrostatic interparticle interaction is applied to the study of the density profiles, adsorption and selectivity of adsorption of ions and solvent species. Our principal focus, however, is in the dependence of differential capacitance on the applied voltage, on the electrode and on the pore width. We discuss the properties of the model with respect to the behavior of a primitive model, i.e., in the absence of a hardsphere solvent. We observed that the differential capacitance of the SPM on the applied electrostatic potential has the camellike shape unless the ion fraction is high. Moreover, it is documented that the dependence of differential capacitance of the SPM on the pore width is oscillatory, which is in close similarity to the primitive model.07/2014;  [Show abstract] [Hide abstract]
ABSTRACT: Using a simple onedimensional FrenkelKontorowa type model, we have demonstrated that finite commensurate chains may undergo the commensurateincommensurate (CIC) transition when the chain is contaminated by isolated impurities attached to the chain ends. Monte Carlo (MC) simulation has shown that the same phenomenon appears in twodimensional systems with impurities located at the peripheries of finite commensurate clusters.07/2014; 
Article: Adsorptioninduced changes of the structure of the tethered chain layers in a simple fluid.
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ABSTRACT: We use density functional theory to study the influence of fluid adsorption on the structure of grafted chain layer. The chains are modeled as freely jointed spheres. The chain segments and spherical molecules of the fluid interact via the LennardJones potential. The fluid molecules are attracted by the substrate. We calculate the excess adsorption isotherms, the average height of tethered chains, and the force acting on selected segments of the chains. The parameters that were varied include the length of grafted chains, the grafting density, the parameters characterizing fluidchain and fluidsurface interactions, the bulk fluid density, and temperature. We show that depending on the density of the bulk fluid the height of the bonded layer increases, remains constant, or decreases with increasing temperature.The Journal of chemical physics. 06/2014; 140(23):234904.  [Show abstract] [Hide abstract]
ABSTRACT: We investigate microscopic structure, adsorption, and electric properties of a mixture that consists of amphiphilic molecules and charged hard spheres in contact with uncharged or charged solid surfaces. The amphiphilic molecules are modeled as spheres composed of attractive and repulsive parts. The electrolyte component of the mixture is considered in the framework of the restricted primitive model (RPM). The system is studied using a density functional theory that combines fundamental measure theory for hard sphere mixtures, weighted density approach for inhomogeneous charged hard spheres, and a meanfield approximation to describe anisotropic interactions. Our principal focus is in exploring the effects brought by the presence of ions on the distribution of amphiphilic particles at the wall, as well as the effects of amphiphilic molecules on the electric double layer formed at solid surface. In particular, we have found that under certain thermodynamic conditions a longrange translational and orientational order can develop. The presence of amphiphiles produces changes of the shape of the differential capacitance from symmetric or nonsymmetric belllike to camellike. Moreover, for some systems the value of the potential of the zero charge is nonzero, in contrast to the RPM at a charged surface.The Journal of Chemical Physics 05/2014; 140(17):174706. · 3.12 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Many objects of nanoscopic dimensions involve fluidtethered chain interfaces. These systems are of interest for basic science and for several applications, in particular for design of nanodevices for specific purposes. We review recent developments of theoretical methods in this area of research and in particular of density functional (DF) approaches, which provide important insights into microscopic properties of such interfaces. The theories permit to describe the dependence of adsorption, wettability, solvation forces and electric interfacial phenomena on thermodynamic states and on characteristics of tethered chains. Computer simulations for the problems in question are overviewed as well. Theoretical results are discussed in relation to simulation results and to some experimental observations.03/2014;  [Show abstract] [Hide abstract]
ABSTRACT: We apply a density functional theory to calculate the solvation force in the system involving Janus particles confined between two planar walls. Janus particles are modeled as spheres composed of attractive and repulsive parts and their orientation is described by the vectors representing internal degrees of freedom. We consider the cases of pores with identical walls, as well as the pores with competing walls (the socalled Januslike pores). The density functional approach we employ combines fundamental measure theory with a meanfield approximation for the anisotropic interparticle interaction. We study how the solvation force and the orientational structure of confined particles depend on the competition between the surface field and the interactions between confined molecules and on the parameters of the model such as temperature and density. It is shown that the anisotropic interaction between the confined molecules and the character of the walls significantly influence the solvation force.The Journal of Chemical Physics 12/2013; 139(22):224711. · 3.12 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The structure of grafted chain layers immersed in an explicit solvent consisting of chain molecules is studied using density functional theory. We consider bonded layers built of short grafted chains at a moderate grafting density. We investigate the grafted layers in contact with oligomeric solvents and oligomermonomer solutions. The chain molecules are freely jointed spherical segments. The substrate is assumed to be inert with respect to the grafted chains. The mobile molecules interact with the surface via LennardJones (93) potential. The interactions between mobile chains, monomers, as well as segments of the tethered chains, are described by LennardJones (126) potential. We discuss how the structure of the grafted chain layer depends on the length of mobile chains and strengths of grafted chainoligomer, oligomersubstrate, oligomeroligomer and oligomermonomer interactions. We study the impact of mixture composition on the height of the bonded layer for selected model systems. The results are consistent with previous experimental and simulation data.The Journal of Physical Chemistry B 08/2013; · 3.61 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We propose application of density functional theory to calculate the force acting on a selected segment of a tethered polymer chain that leads to stretching the chain. The density functional allows one to determine the effects due to the presence of other chains and solvent molecules. For high and moderate solvent densities the plot of the force versus the distance of the segment from the surface exhibits oscillatory behavior that has not been predicted by other approaches.The Journal of Chemical Physics 05/2013; 138(20):204707. · 3.12 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We apply a density functional theory to describe properties of a restricted primitive model of an ionic fluid in slitlike pores. The pore walls are modified by grafted chains. The chains are built of uncharged or charged segments. We study the influence of modification of the pore walls on the structure, adsorption, ion selectivity, and the electric double layer capacitance of ionic fluid under confinement. The brush built of uncharged segments acts as a collection of obstacles in the walls vicinity. Consequently, separation of charges requires higher voltages, in comparison to the models without brushes. At high grafting densities the formation of crowdingtype structure is inhibited. The double layer structure becomes more complex in various aspects, if the brushes are built of charged segments. In particular, the evolution of the brush height with the bulk fluid density and with the charge on the walls depends on the length of the blocks of charged spheres as well as on the distribution of charged species along chains. We also investigated how the dependence of the double layer capacitance on the electrostatic potential (or on the charge on the walls) changes with grafting density, the chain length, distribution of charges along the chain, the bulk fluid density, and, finally, with the pore width. The shape of the electric double layer capacitance vs. voltage changes from a camellike to belllike shape, if the bulk fluid density changes from low to moderate and high. If the bulk density is appropriately chosen, it is possible to alter the shape of this curve from the double hump to single hump by changing the grafting density. Moreover, in narrow pores one can observe the capacitance curve with even three humps for a certain set of parameters describing brush. This behavior illustrates how strong the influence of brushes on the electric double layer properties can be, particularly for ionic fluids in narrow pores.The Journal of Chemical Physics 05/2013; 138(20):204715. · 3.12 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We investigate the structure and adsorption of amphiphilic molecules at planar walls modified by tethered chain molecules using density functional theory. The molecules are modeled as spheres composed of a hydrophilic and hydrophobic part. The pinned chains are treated as tangentially jointed spheres that can interact with fluid molecules via orientationdependent forces. Our density functional approach involves fundamental measure theory, thermodynamic perturbation theory for chains and a meanfield approximation for describing the anisotropic interactions. We study the adsorption of the particles, focusing on the competition between the external field (due to the surface and due to attached chain molecules) and the interactioninduced ordering phenomena.The Journal of Physical Chemistry B 01/2013; · 3.61 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We apply recently developed version of a density functional theory [Z. Wang, L. Liu, and I. Neretnieks, J. Phys.: Condens. Matter 23, 175002 (2011)] to study adsorption of a restricted primitive model for an ionic fluid in slitlike pores in the absence of interactions induced by electrostatic images. At present this approach is one of the most accurate theories for such model electric double layers. The dependencies of the differential double layer capacitance on the pore width, on the electrostatic potential at the wall, bulk fluid density, and temperature are obtained. We show that the differential capacitance can oscillate as a function of the pore width dependent on the values of the above parameters. The number of oscillations and their magnitude decrease for high values of the electrostatic potential. For very narrow pores, close to the ion diameter, the differential capacitance tends to a minimum. The dependence of differential capacitance on temperature exhibits maximum at different values of bulk fluid density and applied electrostatic potential.The Journal of Chemical Physics 12/2012; 137(23):234705. · 3.12 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We use a version of the density functional theory to study the solvation force between two plates modified with a tethered layer of chains. The chains are built of tangentially jointed charged spherical segments. The plates are immersed in an electrolyte solution that involves cations, anions and solvent molecules. The latter molecules are modelled as hard spheres. We study the dependence of the solvation force and the structure of chains and of solute molecules on the grafting density, length of chains, architecture of the chains and on concentration of the solute.Condensed Matter Physics 10/2012; 15(3):33801:114. · 0.76 Impact Factor 
Article: Adsorption from oligomermonomer solutions on the surfaces modified with endgrafted chains.
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ABSTRACT: A density functional theory has been applied to study adsorption from oligomermonomer solutions on solid surfaces modified with endgrafted polymers. Chains are modeled as freely jointed tangent spheres. All spherical species interact via LennardJones (126) potential. The grafted chains are not attracted by the surface. Fluid molecules interact with the substrate via LennardJones (93) potential. It is shown how a shape of the relative excess adsorption isotherms depends on such parameters as the oligomer length, the grafting density, oligomersubstrate interactions, oligomergrafted chains interactions, and oligomermonomer interactions in the bulk solution. As attractive interactions between free and grafted chains strengthen, the relative excess adsorption isotherm can change from negative, through Sshaped with an adsorption azeotropic point, to positive in the whole concentration region. A change of oligomermonomer interactions causes the opposite effects. For low grafting densities of attractive bonds, the relative excess of oligomers increases, reaches a maximum, and decreases. The structure of surface layers is also analyzed.The Journal of Physical Chemistry B 10/2012; 116(42):128429. · 3.61 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We apply density functional theory to study adsorption of ions, treated in the framework of the restricted primitive model (RPM), on surfaces modified by tethered polyampholytes. The residual electrostatic contribution to the free energy functional is approximated by using the approach proposed by Wang et al. [J. Phys.: Condens. Matter 23, 175002 (2011)] for simple nonuniform RPMs systems. Our research concentrates on the problems how the distribution of the charges within chains of polyampholytes changes the selectivity of adsorption of ions species, the structure of the surface layer, and its electric properties.The Journal of Chemical Physics 08/2012; 137(7):074707. · 3.12 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A recently proposed local second contact value theorem [Henderson D., Boda D., J. Electroanal. Chem., 2005, 582, 16] for the charge profile of an electric double layer is used in conjunction with the existing Monte Carlo data from the literature to assess the contact behavior of the electrodeion distributions predicted by the density functional theory. The results for the contact values of the co and counterion distributions and their product are obtained for the symmetric valency, restricted primitive model planar double layer for a range of electrolyte concentrations and temperatures. Overall, the theoretical results satisfy the second contact value theorem reasonably well, the agreement with the simulations being semiquantitative or better. The product of the co and counterion contact values as a function of the electrode surface charge density is qualitative with the simulations with increasing deviations at higher concentrations.07/2012;  [Show abstract] [Hide abstract]
ABSTRACT: We study the capillary condensation of a lattice gas with nearest neighbor attraction confined to a slitlike pore filled with frozen obstacles (matrix). First, the lattice Monte Carlo simulations were performed for a slitlike pore without obstacles. Next, the pore filled with obstacles, i.e., confined microporous medium, is prepared by adsorbing and then by quenching a hard sphere fluid in the pore of the width H. The model includes fluidwall attraction; however, the fluidmatrix interaction is entirely repulsive. We have investigated how concentration of obstacles and the pore width H influence the capillary phase diagrams. Our numerical experiments reveal essential changes in the critical temperature and in the shape of the coexistence line with the amount of quenched obstacles.International Journal of Modern Physics C 04/2012; 10(05). · 0.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Using the results of extensive Monte Carlo simulations in the canonical and grand canonical ensembles, we discuss the phase behavior of mixed submonolayer films of krypton and xenon adsorbed on the graphite basal plane. The calculations have been performed using two and threedimensional models of the systems studied. It has been demonstrated that outofplane motion does not affect the properties of the films as long as the total density is well below the monolayer completion and at moderate temperatures. For the total densities close to the monolayer completion, the promotion of particles to the second layer considerably affects the film properties. Our results are in a reasonable agreement with the available experimental data. The melting point of submonolayer films has been shown to exhibit nonmonotonous changes with the film composition, and reaches minimum for the xenon concentration of about 50%. At the temperatures below the melting point, the structure of solid phases depends upon the film composition and the temperature; one can also distinguish commensurate and incommensurate phases. Twodimensional calculations have demonstrated that for the xenon concentration between about 15% and 65% the adsorbed film exhibits the formation of a superstructure, in which each Xe atom is surrounded by six Kr atoms. This superstructure is stable only at very low temperatures and transforms into the mixed commensurate (√3×√3)R30° phase upon the increase of temperature. Such a superstructure does not appear when a threedimensional model is used. Grand canonical ensemble calculations allowed us to show that for the xenon concentration of about 3% the phase diagram topology of monolayer films changes from the kryptonlike (with incipient triple point) to the xenonlike (with ordinary triple point).The Journal of Chemical Physics 04/2012; 136(14):144702. · 3.12 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A density functional study of adsorption from binary solutions on surfaces modified with tethered chains is presented. The tethered chains are modeled as freely jointed tangent spheres. The fluid molecules are spherical. All species interact via the LennardJones (126) potential. The substrate is neutral with respect to all chain segments but the surfacebinding segment, and it interacts with the fluid molecules via a LennardJones (93) potential. Depending on the parameters of the model, different shapes of the relative excess adsorption isotherms are found. The density profiles of all components are analyzed. It is shown that the surface region is highly inhomogeneous. An influence of the grafting density, the length of grafted chains, the nature of the solution, and its composition on the adsorption mechanism and the structure of the bondedphase is investigated. The theoretical predictions are consistent with the results of computer simulations and experimental data.The Journal of Physical Chemistry B 03/2012; 116(10):311524. · 3.61 Impact Factor 
Article: Changes in the structure of tethered chain molecules as predicted by density functional approach
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ABSTRACT: We use a version of the density functional theory to study the changes in the height of the tethered layer of chains built of jointed spherical segments with the change of the length and surface density of chains. For the model in which the interactions between segments and solvent molecules are the same as between solvent molecules we have discovered two effects that have not been observed in previous studies. Under certain conditions and for low surface concentrations of the chains, the height of the pinned layer may attain a minimum. Moreover, for some systems we observe that when the temperature increases, the height of the layer of chains may decrease.02/2012;  [Show abstract] [Hide abstract]
ABSTRACT: Using Monte Carlo simulation methods in the canonical and grand canonical ensembles, we study the melting and the structure of lowtemperature phases of mixed Ar–Kr submonolayer films on graphite. It is shown that such films exhibit a complete mixing in the liquid phase and freeze into a mixed solid phase, independently of the composition. The structure of the solid phase, however, depends upon the film composition, its total density, and the temperature. For submonolayer coverages, when the mole fraction of Kr is lower than about 0.1, the mixture freezes into the incommensurate, argonlike phase. For the higher mole fractions of Kr, the freezing leads to the formation of a mixed commensurate (√3 × √3)R30° phase. The lowering of temperature leads to structural phase transitions in the solid. When the krypton mole fraction is lower than about 0.88, the transition leads to the formation of domainwall structures, in which the commensurate domains are made of krypton atoms, while the composition of walls depends upon the Kr mole fraction. It is shown that even rather small concentrations of argon atoms can trigger the commensurate–incommensurate transition. For still higher Kr mole fractions, exceeding about 0.88, the commensurate, kryptonlike, solid phase is stable at any temperatures below the melting point. At sufficiently low temperatures, the phase separation takes place and argon atoms are removed from the film interior to the peripheries of submonolayer. In the case of films with the total density close to the monolayer completion, the commensurate structure shows much higher stability. It is demonstrated, however, that it is an artifact of the simulation methods used and, in particular, of the periodic boundary conditions applied, rather than a real phenomenon. It is also demonstrated that the phase diagram topology of monolayer films changes with the film composition. In particular, the vapor–liquid critical point appears only when krypton concentration is lower than about 0.45.The Journal of Physical Chemistry C. 12/2011; 116(1):753–763.
Publication Stats
767  Citations  
387.74  Total Impact Points  
Top Journals
Institutions

1978–2014

Maria CurieSklodowska University in Lublin
 • Department for The Modelling of Physicochemical Processes
 • Faculty of Chemistry
 • Institute of Biology and Biochemistry
 • Department of Theoretical Chemistry
Lyublin, Lublin Voivodeship, Poland


2005–2013

Universidad Nacional Autónoma de México
 Institute of Chemistry
Mexico City, The Federal District, Mexico 
Charles University in Prague
 Ústav teoretické fyziky
Praha, Hlavni mesto Praha, Czech Republic


2012

FriedrichAlexander Universität ErlangenNürnberg
Erlangen, Bavaria, Germany


2011

National Academy of Sciences of Ukraine
 Institute for Condensed Matter Physics
Kharkiv, Kharkivs'ka Oblast', Ukraine


1994–2011

Medical University of Lublin
 Department of Physical Chemistry
Lublin, Lublin Voivodeship, Poland


1999–2009

Polish Academy of Sciences
 Instytut Fizyki
Warsaw, Masovian Voivodeship, Poland 
Institute of Physics of the National Academy of Science of Ukraine
Kievo, Kyiv City, Ukraine


1995–2009

Metropolitan Autonomous University
 Departamento de Física
Ciudad de México, The Federal District, Mexico


2006

University of Natural Resources and Life Science Vienna
 Institut für Verfahrens und Energietechnik (IVET)
Vienna, Vienna, Austria 
Centrum OnkologiiInstytut im. Marii SkłodowskiejCurie
Warszawa, Masovian Voivodeship, Poland


1981–2004

Maria SkłodowskaCurie Institute of Oncology
Cracovia, Lesser Poland Voivodeship, Poland


1996–1999

Brigham Young University  Idaho
 Department of Chemistry
Mesa, Arizona, United States


1998

Brigham Young University  Provo Main Campus
 Department of Chemistry and Biochemistry
Provo, UT, United States


1992

RuhrUniversität Bochum
 Institut Thermo und Fluiddynamik
Bochum, North RhineWestphalia, Germany
