http://www.mdpi.com/journal/polymers/special_issues/polyelectrolytes/ {snippet name="submission_info"} http://www.mdpi.com/2073-4360/3/2/942/ The assembly of sodium polystyrene sulfonate (Na+-PSS) at the surface of single-walled carbon nanotubes (SWNTs) in pH 3 aqueous solution is described. Rather than forming linear or sheet-like chain morphologies over SWNT surfaces, Na+-PSS adopts a spherically collapsed conformation believed to be the result of cation (either Na+ or H+) condensation onto the ionized polymer chain. It is well reported that cations (and also anions) adsorb preferentially onto single-walled and multi-walled carbon nanotube surfaces leading to an increased ion concentration in the near surface regions relative to the bulk solution. This work provides experimental evidence for preferentially absorbed cation condensation onto PSS anions until those cations are spaced at distances corresponding to the Bjerrum length ( B), as defined by the Manning theory of ion condensation, at the SWNT surface. The resulting electrostearic repulsions allow the SWNTs to remain suspended for days. Furthermore , coulombic repulsion among SWNT bundles after cation adsorption alone is not sufficient to form stable suspensions—but rather the stearic repulsions associated with spherically collapsed PSS at the nanotube surface is responsible for suspension stability. It is believed that the ultrasonic agitation drives cations into the small spaces between SWNT bundles and coulombic potential attracts the PSS to those regions. http://www.mdpi.com/2073-4360/3/2/942/ Tue, 14 Jun 2011 00:00:00 CEST Polymers 2011-06-14 3 2 Article 942 954 2073-4360 Behavior of Na+-Polystyrene Sulfonate at the Interface with Single-Walled Carbon Nanotubes (SWNTs) and Its Implication to SWNT Suspension Stability 2011-06-14 doi: 10.3390/polym3020942 Tabbetha Dobbins Richard Chevious Yuri Lvov http://www.mdpi.com/2073-4360/3/2/915/ Flocculation of precipitated calcium carbonate (PCC) was monitored using light diffraction spectroscopy (LDS). Four cationic polyacrylamides of high molar mass and with different degrees of branching, all copolymers of acrylamide (AM) and acryloyloxyethyltrimethyl ammonium chloride (Q9), were tested. LDS supplied information about the kinetic curves for flocs growth and also for the flocs structure evolution. Flocculation kinetics, flocs size and structure, flocs resistance and reflocculation capacity could be correlated with the degree of branching of the polyelectrolytes (PEL). Furthermore, PEL with different degrees of branching corresponded to different values for the intrinsic viscosity, indicating differences in the polymer conformation, which explained well the performance differences in flocculation. http://www.mdpi.com/2073-4360/3/2/915/ Fri, 27 May 2011 00:00:00 CEST Polymers 2011-05-27 3 2 Article 915 927 2073-4360 Using Light Scattering to Screen Polyelectrolytes (PEL) Performance in Flocculation 2011-05-27 doi: 10.3390/polym3020915 Maria G. Rasteiro Ineide Pinheiro Fernando A. P. Garcia Paulo Ferreira David Hunkeler http://www.mdpi.com/2073-4360/3/2/812/ PAMAM dendrimers are used as a model system to investigate the effects of counterion condensation and the effective charge for spherical polyelectrolytes. Because of their amino groups, PAMAM dendrimers are weak polyelectrolytes. Lowering the pH results in an increasing protonation of the amino groups which is monitored via the proton chemical shifts of the adjacent CH2 groups. The effective charge is determined from a combination of diffusion and electrophoresis NMR. The fraction of the charges, which are effective for the interaction with an external electric field or other charges, decreases with increasing generation (size) of the dendrimers. http://www.mdpi.com/2073-4360/3/2/812/ Wed, 27 Apr 2011 00:00:00 CEST Polymers 2011-04-27 3 2 Article 812 819 2073-4360 Counterion Condensation and Effective Charge of PAMAM Dendrimers 2011-04-27 doi: 10.3390/polym3020812 Ute Böhme Anja Klenge Brigitte Hänel Ulrich Scheler http://www.mdpi.com/2073-4360/3/2/762/ In this contribution we outline polyelectrolyte (PEL) complex (PEC) nanoparticles, prepared by mixing solutions of the low cost PEL components poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAC). It was found, that the size and internal structure of PEI/PAC particles can be regulated by process, media and structural parameters. Especially, mixing order, mixing ratio, PEL concentration, pH and molecular weight, were found to be sensible parameters to regulate the size (diameter) of spherical PEI/PAC nanoparticles, in the range between 80–1,000 nm, in a defined way. Finally, applications of dispersed PEI/PAC particles as additives for the paper making process, as well as for drug delivery, are outlined. PEI/PAC nanoparticles mixed directly on model cellulose film showed a higher adsorption level applying the mixing order 1. PAC 2. PEI compared to 1. PEI 2. PAC. Surface bound PEI/PAC nanoparticles were found to release a model drug compound and to stay immobilized due to the contact with the aqueous release medium. http://www.mdpi.com/2073-4360/3/2/762/ Tue, 12 Apr 2011 00:00:00 CEST Polymers 2011-04-12 3 2 Article 762 778 2073-4360 Polyelectrolyte Complex Nanoparticles of Poly(ethyleneimine) and Poly(acrylic acid): Preparation and Applications 2011-04-12 doi: 10.3390/polym3020762 Martin Müller Bernd Keßler Johanna Fröhlich Sebastian Poeschla Bernhard Torger http://www.mdpi.com/2073-4360/3/1/587/ Aqueous two-phase systems consisting of polyethylene glycol (PEG), sodium polyacrylate (NaPAA), and a salt have been studied. The effects of the polymer size, salt type (NaCl, Na2SO4, sodium adipate and sodium azelate) and salt concentrations on the position of the binodal curve were investigated. The investigated PEG molecules had a molar mass of 2,000 to 8,000 g/mol, while that of NaPAA was 8,000 g/mol. Experimental phase diagrams, and tie lines and calculated phase diagrams, based on Flory-Huggins theory of polymer solutions are presented. Due to strong enthalpic and entropic balancing forces, the hydrophobicity of the added salt has a strong influence on the position of the binodal, which could be reproduced by model calculations. http://www.mdpi.com/2073-4360/3/1/587/ Wed, 09 Mar 2011 00:00:00 CET Polymers 2011-03-09 3 1 Article 587 601 2073-4360 Phase Diagrams of the Aqueous Two-Phase Systems of Poly(ethylene glycol)/Sodium Polyacrylate/Salts 2011-03-09 doi: 10.3390/polym3010587 Hans-Olof Johansson Eloi Feitosa Adalberto Pessoa Junior http://www.mdpi.com/2073-4360/2/4/690/ Assembling polyelectrolyte multilayers in a bottom-up approach is reported for polymers, particles, nanoparticles, and carbon nanotubes. Effects of polyelectrolyte multilayers on evaporative self-assembly of particles, which are of interest to a number of applications including photonic crystals, films and substrates, are investigated. Polyelectrolyte multilayer coatings bring multifunctionality to spherical particles and planar films. Studying the construction of polyelectrolyte assemblies is convenient in the planar layout: it is reported here for incorporation of gold and magnetic nanoparticles as well as of carbon nanotubes. Gold nanoparticles concentration is controlled within the films. Potential applications of both spherical structures and planar films are highlighted. http://www.mdpi.com/2073-4360/2/4/690/ Thu, 09 Dec 2010 00:00:00 CET Polymers 2010-12-09 2 4 Article 690 708 2073-4360 Polyelectrolytes: Influence on Evaporative Self-Assembly of Particles and Assembly of Multilayers with Polymers, Nanoparticles and Carbon Nanotubes 2010-12-09 doi: 10.3390/polym2040690 Irina Marchenko Alexey Yashchenok Sergey German Olga Inozemtseva Dmitry Gorin Tatiana Bukreeva Helmuth Mohwald Andre Skirtach http://www.mdpi.com/2073-4360/2/4/681/ Glucan particles (GPs) are 2–4 mm spherical, hollow, porous shells extracted from Baker’s yeast, Saccharomyces cerevisae. The surface of the GPs is composed primarily of 1,3-b-glucan and the particles are efficiently phagocytosed via receptor-mediated cell uptake by macrophages, phagocytic cells expressing glucan receptors. The hollow cavity of the GPs allows for efficient absorption and encapsulation of payload molecules. Rifampicin (Rif), a drug used in tuberculosis treatment, was encapsulated by precipitation in GPs and trapped using a calcium alginate or chitosan hydrogel to seal the pores of GPs and slow Rif release. Unplugged GP formulations immediately released Rif following particle resuspension in aqueous buffer. Alginate and chitosan sealing of GPs loaded with Rif was able to extend drug release for 24–72 h. GP-Rif formulations containing 10% w/w Rif/GP plugged with a calcium alginate hydrogel were effective at reducing colony forming units of M. tuberculosis strain mc26020 in infected bone marrow macrophages ~80–90% at 24 and 72 hours. The amount of Rif delivered in the GP formulations was below the free Rif minimal inhibitory concentration demonstrating that GP targeted Rif delivery to macrophages enhances Rif antimicrobial effects. http://www.mdpi.com/2073-4360/2/4/681/ Mon, 06 Dec 2010 00:00:00 CET Polymers 2010-12-06 2 4 Article 681 689 2073-4360 Glucan Particle Encapsulated Rifampicin for Targeted Delivery to Macrophages 2010-12-06 doi: 10.3390/polym2040681 Ernesto Soto Yun Seong Kim Jinhee Lee Hardy Kornfeld Gary Ostroff http://www.mdpi.com/2073-4360/2/2/57/ Some new phenomena involved in the physical properties of comb polyelectrolyte solutions are reviewed. Special emphasis is given to synthetic biomimetic materials, and the structures formed by these molecules are compared with those of naturally occurring glycoprotein and proteoglycan solutions. Developments in the determination of the structure and dynamics (viscoelasticity) of comb polymers in solution are also covered. Specifically the appearance of multi-globular structures, helical instabilities, liquid crystalline phases, and the self-assembly of the materials to produce hierarchical comb morphologies is examined. Comb polyelectrolytes are surface active and a short review is made of some recent experiments in this area that relate to their morphology when suspended in solution. We hope to emphasize the wide variety of phenomena demonstrated by the vast range of naturally occurring comb polyelectrolytes and the challenges presented to synthetic chemists designing biomimetic materials. http://www.mdpi.com/2073-4360/2/2/57/ Wed, 26 May 2010 00:00:00 CEST Polymers 2010-05-26 2 2 Review 57 70 2073-4360 Biological and Biomimetic Comb Polyelectrolytes 2010-05-26 doi: 10.3390/polym2020057 Waigh Papagiannopoulos