The Experts below are selected from a list of 3993 Experts worldwide ranked by ideXlab platform
Rudolf Podgornik - One of the best experts on this subject based on the ideXlab platform.
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like charge polymer membrane complexation mediated by multivalent cations one loop dressed strong coupling theory
Journal of Chemical Physics, 2019Co-Authors: Sahin Buyukdagli, Rudolf PodgornikAbstract:We probe the electrostatic mechanism driving adsorption of polyelectrolytes onto like-charged membranes upon the addition of tri- and tetravalent Counterions to a bathing monovalent salt solution. We develop a one-loop-dressed strong coupling theory that treats the monovalent salt at the electrostatic one-loop level and the multivalent Counterions within a strong-coupling approach. It is shown that the adhesive force of the multivalent Counterions mediating the like-charge adsorption arises from their strong condensation at the charged membrane. The resulting interfacial Counterion excess locally maximizes the screening ability of the electrolyte and minimizes the electrostatic polymer grand potential. This translates into an attractive force that pulls the polymer to the similarly charged membrane. We show that the high Counterion valency enables this adsorption transition even at weakly charged membranes. Additionally, strongly charged membranes give rise to monovalent Counterion-induced correlations and intensify the interfacial multivalent Counterion condensation, strengthening the complexation of the polymer with the like-charged membrane, as well as triggering the orientational transition of the molecule prior to its adsorption. Finally, our theory provides two additional key features as evidenced by previous adsorption experiments: first, the critical Counterion Concentration for polymer adsorption decreases with the rise of the Counterion valency and, second, the addition of monovalent salt enhances the screening of the membrane charges and suppresses monovalent Counterion correlations close to the surface. This weakens the interfacial multivalent Counterion condensation and results in the desorption of the polymer from the substrate.We probe the electrostatic mechanism driving adsorption of polyelectrolytes onto like-charged membranes upon the addition of tri- and tetravalent Counterions to a bathing monovalent salt solution. We develop a one-loop-dressed strong coupling theory that treats the monovalent salt at the electrostatic one-loop level and the multivalent Counterions within a strong-coupling approach. It is shown that the adhesive force of the multivalent Counterions mediating the like-charge adsorption arises from their strong condensation at the charged membrane. The resulting interfacial Counterion excess locally maximizes the screening ability of the electrolyte and minimizes the electrostatic polymer grand potential. This translates into an attractive force that pulls the polymer to the similarly charged membrane. We show that the high Counterion valency enables this adsorption transition even at weakly charged membranes. Additionally, strongly charged membranes give rise to monovalent Counterion-induced correlations an...
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like charge polymer membrane complexation mediated by multivalent cations one loop dressed strong coupling theory
arXiv: Soft Condensed Matter, 2019Co-Authors: Sahin Buyukdagli, Rudolf PodgornikAbstract:We probe the electrostatic mechanism driving adsorption of polyelectrolytes onto like-charged membranes upon the addition of tri- and tetravalent Counterions to a bathing monovalent salt solution. We develop a one-loop-dressed strong coupling theory that treats the monovalent salt at the electrostatic one-loop level and the multivalent Counterions within a strong-coupling approach. It is shown that the adhesive force of the multivalent Counterions mediating the like-charge adsorption arises from their strong condensation at the charged membrane. The resulting interfacial Counterion excess locally maximizes the screening ability of the electrolyte and minimizes the electrostatic polymer grand potential. This translates into an attractive force that pulls the polymer to the similarly charged membrane. We show that the high Counterion valency enables this adsorption transition even at weakly charged membranes. Additionally, strongly charged membranes give rise to salt-induced correlations and intensify the interfacial multivalent Counterion condensation, strenghtening the complexation of the polymer with the like-charged membrane, as well as triggering the orientational transition of the molecule prior to its adsorption. Finally, our theory provides two additional key features as evidenced by previous adsorption experiments: first, the critical Counterion Concentration for polymer adsorption decreases with the rise of the Counterion valency, and second, the addition of monovalent salt enhances the screening of the membrane charges and suppresses salt correlations. This weakens the interfacial multivalent Counterion condensation and results in the desorption of the polymer from the substrate.
Ernest F. Hasselbrink - One of the best experts on this subject based on the ideXlab platform.
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zeta potential of microfluidic substrates 2 data for polymers
Electrophoresis, 2004Co-Authors: Brian Kirby, Ernest F. HasselbrinkAbstract:Zeta potential data are reviewed for a variety of polymeric microfluidic substrate materials. Many of these materials currently used for microchip fabrication have only recently been employed for generation of electroosmotic flow. Despite their recent history, polymeric microfluidic substrates are currently used extensively for microchip separations and other techniques, and understanding of the surface ζ potential is crucial for experimental design. This paper proposes the use of pC (the negative logarithm of the Counterion Concentration) as a useful normalization for the ζ potential on polymer substrates in contact with indifferent univalent Counterions. Normalizing ζ by pC facilitates comparison of results from many investigators. The sparseness of available data for polymeric substrates prevents complete and rigorous justification for this normalization; however, it is consistent with double layer and adsorption theory. For buffers with indifferent univalent cations, normalization with the logarithm of the Counterion Concentration in general collapses data onto a single ζ/pC vs. pH curve, and (with the exception of PMMA) the repeatability of the data is quite encouraging. Normalization techniques should allow improved ability to predict ζ potential performance on microfluidic substrates and compare results observed with different parameters.
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zeta potential of microfluidic substrates 1 theory experimental techniques and effects on separations
Electrophoresis, 2004Co-Authors: Brian Kirby, Ernest F. HasselbrinkAbstract:This paper summarizes theory, experimental techniques, and the reported data pertaining to the zeta potential of silica and silicon with attention to use as microfluidic substrate materials, particularly for microchip chemical separations. Dependence on cation Concentration, buffer and cation type, pH, cation valency, and temperature are discussed. The Debye-Huckel limit, which is often correctly treated as a good approximation for describing the ion Concentration in the double layer, can lead to serious errors if it is extended to predict the dependence of zeta potential on the Counterion Concentration. For indifferent univalent electrolytes (e.g., sodium and potassium), two simple scalings for the dependence of zeta potential on Counterion Concentration can be derived in high- and low-z limits of the nonlinear Poisson-Boltzman equation solution in the double layer. It is shown that for most situations relevant to microchip separations, the high-z limit is most applicable, leading to the conclusion that the zeta potential on silica substrates is approximately proportional to the logarithm of the molar Counterion Concentration. The z vs. pH dependence measurements from several experiments are compared by normalizing the z based on Concentration.
Matthias Ballauff - One of the best experts on this subject based on the ideXlab platform.
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spherical polyelectrolyte brushes in the presence of multivalent Counterions the effect of fluctuations and correlations as determined by molecular dynamics simulations
Physical Review E, 2008Co-Authors: Matthias Ballauff, Arben JusufiAbstract:We consider the interaction of multivalent Counterions with spherical polyelectrolyte brushes (SPBs). SPBs result if linear polyelectrolyte chains (contour length 60 nm) are densely grafted to colloidal spheres of 116 nm in diameter. When dispersed in water the surface layer, consisting of chains of the strong polyelectrolyte poly(styrene sulfonic acid), will swell. Recent work [Mei, Phys. Rev. Lett. 97, 158301 (2006)] has demonstrated that spherical polyelectrolyte brushes undergo a collapse in the presence of a mixture of monovalent and multivalent Counterions. The collapse crossover could be well described by a mean-field approach. Here we demonstrate that the application of a mean-field approach is well founded by simulation results done with molecular dynamics (MD). MD simulations show that over a wide range of multivalent Counterion Concentration the effects of ion correlation and fluctuations can be neglected. Higher-valent Counterions are shown to interact strongly with the polyelectrolyte chains of the SPBs and thus exhibit a much reduced osmotic activity in the system. This reduction is the driving force for the collapse.
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nanoblossoms light induced conformational changes of cationic polyelectrolyte stars in the presence of multivalent Counterions
Nano Letters, 2007Co-Authors: Felix A. Plamper, Andreas Walther, Axel H E Muller, Matthias BallauffAbstract:We analyze the structure of star-shaped polyelectrolytes in the presence of di- and trivalent Counterions, and we use the gained knowledge to manipulate the polyelectrolyte's conformation by light. By applying dynamic light scattering and atomic force microscopy, we demonstrate that, at constant ionic strength, the arms of the cationic polyelectrolyte retract when adding multivalent Counterions. Adding trivalent hexacyanocobaltate(III) ions leads to a collapse of the polyelectrolyte star even at low Concentrations. This is shown by analysis of the star polyelectrolytes in solution as well as in the adsorbed state on mica surfaces. Considerably higher salt Concentrations are necessary to obtain the same contraction of the polyelectrolyte star if the divalent tetracyanonickelate(II) ions are used. Sufficiently high multivalent Counterion Concentration leads finally to the precipitation of the polymer from the solution. We demonstrate that we can switch a polyelectrolyte star from the collapsed to the expand...
Brian Kirby - One of the best experts on this subject based on the ideXlab platform.
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zeta potential of microfluidic substrates 2 data for polymers
Electrophoresis, 2004Co-Authors: Brian Kirby, Ernest F. HasselbrinkAbstract:Zeta potential data are reviewed for a variety of polymeric microfluidic substrate materials. Many of these materials currently used for microchip fabrication have only recently been employed for generation of electroosmotic flow. Despite their recent history, polymeric microfluidic substrates are currently used extensively for microchip separations and other techniques, and understanding of the surface ζ potential is crucial for experimental design. This paper proposes the use of pC (the negative logarithm of the Counterion Concentration) as a useful normalization for the ζ potential on polymer substrates in contact with indifferent univalent Counterions. Normalizing ζ by pC facilitates comparison of results from many investigators. The sparseness of available data for polymeric substrates prevents complete and rigorous justification for this normalization; however, it is consistent with double layer and adsorption theory. For buffers with indifferent univalent cations, normalization with the logarithm of the Counterion Concentration in general collapses data onto a single ζ/pC vs. pH curve, and (with the exception of PMMA) the repeatability of the data is quite encouraging. Normalization techniques should allow improved ability to predict ζ potential performance on microfluidic substrates and compare results observed with different parameters.
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zeta potential of microfluidic substrates 1 theory experimental techniques and effects on separations
Electrophoresis, 2004Co-Authors: Brian Kirby, Ernest F. HasselbrinkAbstract:This paper summarizes theory, experimental techniques, and the reported data pertaining to the zeta potential of silica and silicon with attention to use as microfluidic substrate materials, particularly for microchip chemical separations. Dependence on cation Concentration, buffer and cation type, pH, cation valency, and temperature are discussed. The Debye-Huckel limit, which is often correctly treated as a good approximation for describing the ion Concentration in the double layer, can lead to serious errors if it is extended to predict the dependence of zeta potential on the Counterion Concentration. For indifferent univalent electrolytes (e.g., sodium and potassium), two simple scalings for the dependence of zeta potential on Counterion Concentration can be derived in high- and low-z limits of the nonlinear Poisson-Boltzman equation solution in the double layer. It is shown that for most situations relevant to microchip separations, the high-z limit is most applicable, leading to the conclusion that the zeta potential on silica substrates is approximately proportional to the logarithm of the molar Counterion Concentration. The z vs. pH dependence measurements from several experiments are compared by normalizing the z based on Concentration.
Sahin Buyukdagli - One of the best experts on this subject based on the ideXlab platform.
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like charge polymer membrane complexation mediated by multivalent cations one loop dressed strong coupling theory
Journal of Chemical Physics, 2019Co-Authors: Sahin Buyukdagli, Rudolf PodgornikAbstract:We probe the electrostatic mechanism driving adsorption of polyelectrolytes onto like-charged membranes upon the addition of tri- and tetravalent Counterions to a bathing monovalent salt solution. We develop a one-loop-dressed strong coupling theory that treats the monovalent salt at the electrostatic one-loop level and the multivalent Counterions within a strong-coupling approach. It is shown that the adhesive force of the multivalent Counterions mediating the like-charge adsorption arises from their strong condensation at the charged membrane. The resulting interfacial Counterion excess locally maximizes the screening ability of the electrolyte and minimizes the electrostatic polymer grand potential. This translates into an attractive force that pulls the polymer to the similarly charged membrane. We show that the high Counterion valency enables this adsorption transition even at weakly charged membranes. Additionally, strongly charged membranes give rise to monovalent Counterion-induced correlations and intensify the interfacial multivalent Counterion condensation, strengthening the complexation of the polymer with the like-charged membrane, as well as triggering the orientational transition of the molecule prior to its adsorption. Finally, our theory provides two additional key features as evidenced by previous adsorption experiments: first, the critical Counterion Concentration for polymer adsorption decreases with the rise of the Counterion valency and, second, the addition of monovalent salt enhances the screening of the membrane charges and suppresses monovalent Counterion correlations close to the surface. This weakens the interfacial multivalent Counterion condensation and results in the desorption of the polymer from the substrate.We probe the electrostatic mechanism driving adsorption of polyelectrolytes onto like-charged membranes upon the addition of tri- and tetravalent Counterions to a bathing monovalent salt solution. We develop a one-loop-dressed strong coupling theory that treats the monovalent salt at the electrostatic one-loop level and the multivalent Counterions within a strong-coupling approach. It is shown that the adhesive force of the multivalent Counterions mediating the like-charge adsorption arises from their strong condensation at the charged membrane. The resulting interfacial Counterion excess locally maximizes the screening ability of the electrolyte and minimizes the electrostatic polymer grand potential. This translates into an attractive force that pulls the polymer to the similarly charged membrane. We show that the high Counterion valency enables this adsorption transition even at weakly charged membranes. Additionally, strongly charged membranes give rise to monovalent Counterion-induced correlations an...
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like charge polymer membrane complexation mediated by multivalent cations one loop dressed strong coupling theory
arXiv: Soft Condensed Matter, 2019Co-Authors: Sahin Buyukdagli, Rudolf PodgornikAbstract:We probe the electrostatic mechanism driving adsorption of polyelectrolytes onto like-charged membranes upon the addition of tri- and tetravalent Counterions to a bathing monovalent salt solution. We develop a one-loop-dressed strong coupling theory that treats the monovalent salt at the electrostatic one-loop level and the multivalent Counterions within a strong-coupling approach. It is shown that the adhesive force of the multivalent Counterions mediating the like-charge adsorption arises from their strong condensation at the charged membrane. The resulting interfacial Counterion excess locally maximizes the screening ability of the electrolyte and minimizes the electrostatic polymer grand potential. This translates into an attractive force that pulls the polymer to the similarly charged membrane. We show that the high Counterion valency enables this adsorption transition even at weakly charged membranes. Additionally, strongly charged membranes give rise to salt-induced correlations and intensify the interfacial multivalent Counterion condensation, strenghtening the complexation of the polymer with the like-charged membrane, as well as triggering the orientational transition of the molecule prior to its adsorption. Finally, our theory provides two additional key features as evidenced by previous adsorption experiments: first, the critical Counterion Concentration for polymer adsorption decreases with the rise of the Counterion valency, and second, the addition of monovalent salt enhances the screening of the membrane charges and suppresses salt correlations. This weakens the interfacial multivalent Counterion condensation and results in the desorption of the polymer from the substrate.
