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Special Issue "Polyelectrolytes 2014"

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A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (31 March 2014)

Special Issue Editor

Guest Editor
Dr. Christian Seidel

Max Planck Institute of Colloids and Interfaces, Department of Theory & Bio-Systems, Science Park Golm, D-14424 Potsdam, Germany
Website | E-Mail
Phone: +49 331 567 9608
Fax: +49 331 567 9612
Interests: polymers and polyelectrolytes in solution and at interfaces; polyelectrolyte brushes; organization of nanoparticles at copolymer brushes; numerical simulations and theory

Special Issue Information

Dear Colleagues,

Synthetic and natural polyelectrolytes have been the subject of fundamental and applied studies for nearly a century. Due to substantial advances both in experimental methods and theoretical approaches, since the 1990’s polyelectrolyte research has undergone a considerable speed-up. On the one hand, interest in polyelectrolytes is spurred by their fascinating properties, such as water solubility, intra- and interchain interactions, the strength of which can be tuned simply by varying salt concentration, and ionic conductivity. These properties make polyelectrolytes attractive from the application-oriented point of view, such as stabilizer of colloidal suspensions, additives to modify flocculation and viscosity, and superabsorbers. Functional polyelectrolytes combine the useful properties intrinsic to polyelectrolytes with added functionality provided by specific features of the polymer backbone, such as delocalized electrons in conjugated chains. Combined functionality can be used to create materials with highly interesting optical, electro-optical, and electronic properties.

On the other hand, the understanding of polyelectrolytes still belongs to the most challenging and most exciting problems in polymer physics and physical chemistry. Despite much effort and substantial progress during the last two decades, much more work is ahead to achieve a quantitative agreement between theory and experiments for a lot of problems, such as counterion condensation, chain stiffness, and formation of complexes. It is still a major open problem to have a satisfactory model explaining the coupling between small ions in solutions and polyelectrolyte charges, which is necessary to understand how electrostatics affects the behavior of polyelectrolytes.

Many biologically relevant macromolecules, such as nucleic acids, polypeptides, and polysaccharides, are polyelectrolytes. Electrophoresis is a well-established method for the fractionation of polyelectrolytes and more specifically, DNA. Hydration-mediated interactions play an important role in the field of biological polyelectrolytes, but are not well understood on nano-scales.

Dr. Christian Seidel
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs).

Keywords

  • synthesis and biopolyelectrolytes
  • stimuli-responsive polyelectrolytes
  • electrophoresis
  • hydration effects and ion-specific interactions
  • polyelectrolyte multilayers, complexes and gels
  • polyelectrolyte brushes
  • conjugated polyelectrolytes
  • theory and modeling

Published Papers (12 papers)

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Research

Jump to: Review

Open AccessArticle Charge Inversion Effects in Electrophoresis of Polyelectrolytes in the Presence of Multivalent Counterions and Transversal Electric Fields
Polymers 2014, 6(12), 2942-2960; doi:10.3390/polym6122942
Received: 2 August 2014 / Revised: 14 November 2014 / Accepted: 20 November 2014 / Published: 4 December 2014
PDF Full-text (646 KB) | HTML Full-text | XML Full-text
Abstract
By molecular dynamics simulations we investigate the transport of charged polymers in confinement, under externally applied electric fields, in straight cylinders of uniform diameter and in the presence of monovalent or multivalent counterions. The applied electric field has two components; a longitudinal component
[...] Read more.
By molecular dynamics simulations we investigate the transport of charged polymers in confinement, under externally applied electric fields, in straight cylinders of uniform diameter and in the presence of monovalent or multivalent counterions. The applied electric field has two components; a longitudinal component along the axis of the cylinder and a transversal component perpendicular to the cylinder axis. The direction of electrophoretic velocity depends on the polyelectrolyte length, valency of the counterions present in solution and transversal electric field value. A statistical model is put forward in order to explain these observations. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessArticle Lipid Monolayers with Adsorbed Oppositely Charged Polyelectrolytes: Influence of Reduced Charge Densities
Polymers 2014, 6(7), 1999-2017; doi:10.3390/polym6071999
Received: 30 April 2014 / Revised: 26 June 2014 / Accepted: 27 June 2014 / Published: 10 July 2014
Cited by 1 | PDF Full-text (801 KB) | HTML Full-text | XML Full-text
Abstract
Polyelectrolytes in dilute solutions (0.01 mmol/L) adsorb in a two-dimensional lamellar phase to oppositely charged lipid monolayers at the air/water interface. The interchain separation is monitored by Grazing Incidence X-ray Diffraction. On monolayer compression, the interchain separation decreases to a factor of two.
[...] Read more.
Polyelectrolytes in dilute solutions (0.01 mmol/L) adsorb in a two-dimensional lamellar phase to oppositely charged lipid monolayers at the air/water interface. The interchain separation is monitored by Grazing Incidence X-ray Diffraction. On monolayer compression, the interchain separation decreases to a factor of two. To investigate the influence of the electrostatic interaction, either the line charge density of the polymer is reduced (a statistic copolymer with 90% and 50% charged monomers) or mixtures between charged and uncharged lipids are used (dipalmitoylphosphatidylcholine (DPPC)/ dioctadecyldimethylammonium bromide (DODAB)) On decrease of the surface charge density, the interchain separation increases, while on decrease of the linear charge density, the interchain separation decreases. The ratio between charged monomers and charged lipid molecules is fairly constant; it decreases up to 30% when the lipids are in the fluid phase. With decreasing surface charge or linear charge density, the correlation length of the lamellar order decreases. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessArticle Salt Effect on Osmotic Pressure of Polyelectrolyte Solutions: Simulation Study
Polymers 2014, 6(7), 1897-1913; doi:10.3390/polym6071897
Received: 21 March 2014 / Revised: 24 June 2014 / Accepted: 26 June 2014 / Published: 4 July 2014
Cited by 5 | PDF Full-text (1079 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Abstract: We present results of the hybrid Monte Carlo/molecular dynamics simulations of the osmotic pressure of salt solutions of polyelectrolytes. In our simulations, we used a coarse-grained representation of polyelectrolyte chains, counterions and salt ions. During simulation runs, we alternate Monte Carlo
[...] Read more.
Abstract: We present results of the hybrid Monte Carlo/molecular dynamics simulations of the osmotic pressure of salt solutions of polyelectrolytes. In our simulations, we used a coarse-grained representation of polyelectrolyte chains, counterions and salt ions. During simulation runs, we alternate Monte Carlo and molecular dynamics simulation steps. Monte Carlo steps were used to perform small ion exchange between simulation box containing salt ions (salt reservoir) and simulation box with polyelectrolyte chains, counterions and salt ions (polyelectrolyte solution). This allowed us to model Donnan equilibrium and partitioning of salt and counterions across membrane impermeable to polyelectrolyte chains. Our simulations have shown that the main contribution to the system osmotic pressure is due to salt ions and osmotically active counterions. The fraction of the condensed (osmotically inactive) counterions first increases with decreases in the solution ionic strength then it saturates. The reduced value of the system osmotic coefficient is a universal function of the ratio of the concentration of osmotically active counterions and salt concentration in salt reservoir. Simulation results are in a very good agreement with osmotic pressure measurements in sodium polystyrene sulfonate, DNA, polyacrylic acid, sodium polyanetholesulfonic acid, polyvinylbenzoic acid, and polydiallyldimethylammonium chloride solutions. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
Open AccessArticle Stimuli-Responsive Polyelectrolyte Brushes As a Matrix for the Attachment of Gold Nanoparticles: The Effect of Brush Thickness on Particle Distribution
Polymers 2014, 6(7), 1877-1896; doi:10.3390/polym6071877
Received: 16 April 2014 / Revised: 23 June 2014 / Accepted: 24 June 2014 / Published: 27 June 2014
Cited by 14 | PDF Full-text (1259 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The effect of brush thickness on the loading of gold nanoparticles (AuNPs) within stimuli-responsive poly-(N,N-(dimethylamino ethyl) methacrylate) (PDMAEMA) polyelectrolyte brushes is reported. Atom transfer radical polymerization (ATRP) was used to grow polymer brushes via a “grafting from” approach. The brush thickness was tuned
[...] Read more.
The effect of brush thickness on the loading of gold nanoparticles (AuNPs) within stimuli-responsive poly-(N,N-(dimethylamino ethyl) methacrylate) (PDMAEMA) polyelectrolyte brushes is reported. Atom transfer radical polymerization (ATRP) was used to grow polymer brushes via a “grafting from” approach. The brush thickness was tuned by varying the polymerization time. Using a new type of sealed reactor, thick brushes were synthesized. A systematic study was performed by varying a single parameter (brush thickness), while keeping all other parameters constant. AuNPs of 13 nm in diameter were attached by incubation. X-ray reflectivity, electron scanning microscopy and ellipsometry were used to study the particle loading, particle distribution and interpenetration of the particles within the brush matrix. A model for the structure of the brush/particle hybrids was derived. The particle number densities of attached AuNPs depend on the brush thickness, as do the optical properties of the hybrids. An increasing particle number density was found for increasing brush thickness, due to an increased surface roughness. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessArticle The Effect of Salt on the Complex Coacervation of Vinyl Polyelectrolytes
Polymers 2014, 6(6), 1756-1772; doi:10.3390/polym6061756
Received: 5 May 2014 / Revised: 3 June 2014 / Accepted: 4 June 2014 / Published: 16 June 2014
Cited by 27 | PDF Full-text (1785 KB) | HTML Full-text | XML Full-text
Abstract
Complex coacervation is an electrostatically-driven phase separation phenomenon that is utilized in a wide range of everyday applications and is of great interest for the creation of self-assembled materials. Here, we utilized turbidity to characterize the effect of salt type on coacervate formation
[...] Read more.
Complex coacervation is an electrostatically-driven phase separation phenomenon that is utilized in a wide range of everyday applications and is of great interest for the creation of self-assembled materials. Here, we utilized turbidity to characterize the effect of salt type on coacervate formation using two vinyl polyelectrolytes, poly(acrylic acid sodium salt) (pAA) and poly(allylamine hydrochloride) (pAH), as simple models for industrial and biological coacervates. We confirmed the dominant role of salt valence on the extent of coacervate formation, while demonstrating the presence of significant secondary effects, which can be described by Hofmeister-like behavior. These results revealed the importance of ion-specific interactions, which are crucial for the informed design of coacervate-based materials for use in complex ionic environments, and can enable more detailed theoretical investigations on the role of subtle electrostatic and thermodynamic effects in complex coacervation. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessArticle A Coarse-Grained DNA Model Parameterized from Atomistic Simulations by Inverse Monte Carlo
Polymers 2014, 6(6), 1655-1675; doi:10.3390/polym6061655
Received: 15 April 2014 / Revised: 15 May 2014 / Accepted: 18 May 2014 / Published: 30 May 2014
Cited by 15 | PDF Full-text (815 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Computer modeling of very large biomolecular systems, such as long DNA polyelectrolytes or protein-DNA complex-like chromatin cannot reach all-atom resolution in a foreseeable future and this necessitates the development of coarse-grained (CG) approximations. DNA is both highly charged and mechanically rigid semi-flexible polymer
[...] Read more.
Computer modeling of very large biomolecular systems, such as long DNA polyelectrolytes or protein-DNA complex-like chromatin cannot reach all-atom resolution in a foreseeable future and this necessitates the development of coarse-grained (CG) approximations. DNA is both highly charged and mechanically rigid semi-flexible polymer and adequate DNA modeling requires a correct description of both its structural stiffness and salt-dependent electrostatic forces. Here, we present a novel CG model of DNA that approximates the DNA polymer as a chain of 5-bead units. Each unit represents two DNA base pairs with one central bead for bases and pentose moieties and four others for phosphate groups. Charges, intra- and inter-molecular force field potentials for the CG DNA model were calculated using the inverse Monte Carlo method from all atom molecular dynamic (MD) simulations of 22 bp DNA oligonucleotides. The CG model was tested by performing dielectric continuum Langevin MD simulations of a 200 bp double helix DNA in solutions of monovalent salt with explicit ions. Excellent agreement with experimental data was obtained for the dependence of the DNA persistent length on salt concentration in the range 0.1–100 mM. The new CG DNA model is suitable for modeling various biomolecular systems with adequate description of electrostatic and mechanical properties. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessArticle Structure of Microgels with Debye–Hückel Interactions
Polymers 2014, 6(5), 1602-1617; doi:10.3390/polym6051602
Received: 31 March 2014 / Revised: 13 May 2014 / Accepted: 19 May 2014 / Published: 23 May 2014
Cited by 13 | PDF Full-text (1089 KB) | HTML Full-text | XML Full-text
Abstract
The structural properties of model microgel particles are investigated by molecular dynamics simulations applying a coarse-grained model. A microgel is comprised of a regular network of polymers internally connected by tetra-functional cross-links and with dangling ends at its surface. The self-avoiding polymers are
[...] Read more.
The structural properties of model microgel particles are investigated by molecular dynamics simulations applying a coarse-grained model. A microgel is comprised of a regular network of polymers internally connected by tetra-functional cross-links and with dangling ends at its surface. The self-avoiding polymers are modeled as bead-spring linear chains. Electrostatic interactions are taken into account by the Debye–Hückel potential. The microgels exhibit a quite uniform density under bad solvent conditions with a rather sharp surface. With increasing Debye length, structural inhomogeneities appear, their surface becomes fuzzy and, at very large Debye lengths, well defined again. Similarly, the polymer conformations change from a self-avoiding walk to a rod-like behavior. Thereby, the average polymer radius of gyration follows a scaling curve in terms of polymer length and persistence length, with an asymptotic rod-like behavior for swollen microgels and self-avoiding walk behavior for weakly swollen gel particles. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessArticle Development of a Biocompatible Layer-by-Layer Film System Using Aptamer Technology for Smart Material Applications
Polymers 2014, 6(5), 1631-1654; doi:10.3390/polym6051631
Received: 17 March 2014 / Revised: 4 May 2014 / Accepted: 8 May 2014 / Published: 23 May 2014
Cited by 6 | PDF Full-text (2854 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Aptamers are short, single-stranded nucleic acids that fold into well-defined three dimensional (3D) structures that allow for binding to a target molecule with affinities and specificities that can rival or in some cases exceed those of antibodies. The compatibility of aptamers with nanostructures
[...] Read more.
Aptamers are short, single-stranded nucleic acids that fold into well-defined three dimensional (3D) structures that allow for binding to a target molecule with affinities and specificities that can rival or in some cases exceed those of antibodies. The compatibility of aptamers with nanostructures such as thin films, in combination with their affinity, selectivity, and conformational changes upon target interaction, could set the foundation for the development of novel smart materials. In this study, the development of a biocompatible aptamer-polyelectrolyte film system was investigated using a layer-by-layer approach. Using fluorescence microscopy, we demonstrated the ability of the sulforhodamine B aptamer to bind its cognate target while sequestered in a chitosan-hyaluronan film matrix. Studies using Ultraviolet-visible (UV-Vis) spectrophotometry also suggest that deposition conditions such as rinsing time and volume play a strong role in the internal film interactions and growth mechanisms of chitosan-hyaluronan films. The continued study and development of aptamer-functionalized thin films provides endless new opportunities for novel smart materials and has the potential to revolutionize the field of controlled release. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessArticle pH and Salt Effects on the Associative Phase Separation of Oppositely Charged Polyelectrolytes
Polymers 2014, 6(5), 1414-1436; doi:10.3390/polym6051414
Received: 27 March 2014 / Revised: 9 May 2014 / Accepted: 9 May 2014 / Published: 16 May 2014
Cited by 11 | PDF Full-text (3356 KB) | HTML Full-text | XML Full-text
Abstract
The classical Voorn-Overbeek thermodynamic theory of complexation and phase separation of oppositely charged polyelectrolytes is generalized to account for the charge accessibility and hydrophobicity of polyions, size of salt ions, and pH variations. Theoretical predictions of the effects of pH and salt concentration
[...] Read more.
The classical Voorn-Overbeek thermodynamic theory of complexation and phase separation of oppositely charged polyelectrolytes is generalized to account for the charge accessibility and hydrophobicity of polyions, size of salt ions, and pH variations. Theoretical predictions of the effects of pH and salt concentration are compared with published experimental data and experiments we performed, on systems containing poly(acrylic acid) (PAA) as the polyacid and poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) or poly(diallyldimethyl ammonium chloride) (PDADMAC) as the polybase. In general, the critical salt concentration below which the mixture phase separates, increases with degree of ionization and with the hydrophobicity of polyelectrolytes. We find experimentally that as the pH is decreased below 7, and PAA monomers are neutralized, the critical salt concentration increases, while the reverse occurs when pH is raised above 7. We predict this asymmetry theoretically by introducing a large positive Flory parameter (= 0.75) for the interaction of neutral PAA monomers with water. This large positive Flory parameter is supported by molecular dynamics simulations, which show much weaker hydrogen bonding between neutral PAA and water than between charged PAA and water, while neutral and charged PDMAEMA show similar numbers of hydrogen bonds. This increased hydrophobicity of neutral PAA at reduced pH increases the tendency towards phase separation despite the reduction in charge interactions between the polyelectrolytes. Water content and volume of coacervate are found to be a strong function of the pH and salt concentration. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)

Review

Jump to: Research

Open AccessReview Polyelectrolyte Multilayers in Microfluidic Systems for Biological Applications
Polymers 2014, 6(8), 2100-2115; doi:10.3390/polym6082100
Received: 22 May 2014 / Revised: 15 July 2014 / Accepted: 22 July 2014 / Published: 31 July 2014
Cited by 3 | PDF Full-text (1351 KB) | HTML Full-text | XML Full-text
Abstract
The formation of polyelectrolyte multilayers (PEMs) for the first time, two decades ago, demonstrating the assembly on charged substrates in a very simple and efficient way, has proven to be a reliable method to obtain structures tunable at the nanometer scale. Much effort
[...] Read more.
The formation of polyelectrolyte multilayers (PEMs) for the first time, two decades ago, demonstrating the assembly on charged substrates in a very simple and efficient way, has proven to be a reliable method to obtain structures tunable at the nanometer scale. Much effort has been put into the assembly of these structures for their use in biological applications. A number of these efforts have been in combination with microfluidic systems, which add to the nanoassembly that is already possible with polyelectrolytes, a new dimension in the construction of valuable structures, some of them not possible with conventional systems. This review focuses on the advancements demonstrated by the combination of PEMs and microfluidic systems, and their use in biological applications. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessReview Structures and Synthesis of Zwitterionic Polymers
Polymers 2014, 6(5), 1544-1601; doi:10.3390/polym6051544
Received: 16 April 2014 / Revised: 3 May 2014 / Accepted: 8 May 2014 / Published: 23 May 2014
Cited by 44 | PDF Full-text (463 KB) | HTML Full-text | XML Full-text
Abstract
The structures and synthesis of polyzwitterions (“polybetaines”) are reviewed, emphasizing the literature of the past decade. Particular attention is given to the general challenges faced, and to successful strategies to obtain polymers with a true balance of permanent cationic and anionic groups, thus
[...] Read more.
The structures and synthesis of polyzwitterions (“polybetaines”) are reviewed, emphasizing the literature of the past decade. Particular attention is given to the general challenges faced, and to successful strategies to obtain polymers with a true balance of permanent cationic and anionic groups, thus resulting in an overall zero charge. Also, the progress due to applying new methodologies from general polymer synthesis, such as controlled polymerization methods or the use of “click” chemical reactions is presented. Furthermore, the emerging topic of responsive (“smart”) polyzwitterions is addressed. The considerations and critical discussions are illustrated by typical examples. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)
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Open AccessReview Does Electrical Conductivity of Linear Polyelectrolytes in Aqueous Solutions Follow the Dynamic Scaling Laws? A Critical Review and a Summary of the Key Relations
Polymers 2014, 6(4), 1207-1231; doi:10.3390/polym6041207
Received: 14 February 2014 / Revised: 4 April 2014 / Accepted: 11 April 2014 / Published: 22 April 2014
Cited by 3 | PDF Full-text (660 KB) | HTML Full-text | XML Full-text
Abstract
In this review, we focus on the electrical conductivity of aqueous polyelectrolyte solutions in the light of the dynamic scaling laws, recently proposed by Dobrynin and Rubinstein, to take into account the polymer conformations in different concentration regimes, both in good and poor
[...] Read more.
In this review, we focus on the electrical conductivity of aqueous polyelectrolyte solutions in the light of the dynamic scaling laws, recently proposed by Dobrynin and Rubinstein, to take into account the polymer conformations in different concentration regimes, both in good and poor solvent conditions. This approach allows us to separate contributions due to polymer conformation from those due to the ionic character of the chain, and offers the possibility to extend the validity of the Manning conductivity model to dilute and semidilute regimes. The electrical conductivity in the light of the scaling approach compares reasonably well with the observed values for different polyelectrolytes in aqueous solutions, over an extended concentration range, from the dilute to the semidilute regime. Full article
(This article belongs to the Special Issue Polyelectrolytes 2014)

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.


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