Integral Polyelectrolytes

Assuming that the total charge Q of a polyelectrolyte chain is uniformly distributed on the chain backbone so that each segment carries a charge of ezp where e is the electronic charge and by integrating over the positions of counterions, salt ions, and solvent molecules, the potential interaction V between any two segments i and j separated by a distance R,y is taken to be [48]... 

We will discuss here applications of polyelectrolyte-modified electrodes, with particular emphasis on layer-by-layer self-assembled redox polyelectrolyte multilayers. The method offers a series of advantages over traditional technologies to construct integrated electrochemical devices with technological applications in biosensors, electrochromic, electrocatalysis, corrosion prevention, nanofiltration, fuel-cell membranes, and so on. 

The theories of polymer solutions upon which steric-stability theories are based are usually formulated in terms of a portmanteau interaction parameter (for example Flory s X Parameter and the excluded volume integral) which does not preclude electrostatic interactions, particularly under conditions where these are short range. It is thus appropriate to consider whether polyelect-roly te-stabilisation can be understood in the same broad terms as stabilisation by non-ionic polymers. It was this together with the fact that polyelectrolyte solutions containing simple salts show phase-separation behaviour reminiscent of that of non-ionic... 

Michel M, Izquierdo A, Decher G et al (2005) Layer-by-layer self-assembled polyelectrolyte multilayers with embedded phospholipid vesicles obtained by spraying integrity of the vesicles. Langmuir 21 7854-7859... 

Abstract In this chapter we review recent advances which have been achieved in the theoretical description and understanding of polyelectrolyte solutions. We will discuss an improved density functional approach to go beyond mean-field theory for the cell model and an integral equation approach to describe stiff and flexible polyelectrolytes in good solvents and compare some of the results to computer simulations. Then we review some recent theoretical and numerical advances in the theory of poor solvent polyelectrolytes. At the end we show how to describe annealed polyelectrolytes in the bulk and discuss their adsorption properties. 

Keywords Polyelectrolytes Poisson-Boltzmann theory Density functional theory Integral equations Scaling theory Annealed polyelectrolytes Computer Simulations... 

To elucidate the structure of a solution of flexible polyelectrolytes, we again use the integral equation theory approach of Sect. 2.2. The necessary structure factor is determined self-consistently using the reference chain (9) of the last section. The intermolecular interactions are taken into account by a medium-induced intramolecular potential [35, 47,48]... 

Polyelectrolyte complexes can be prepared in a desired range of mass, size and structure density. The behavior of the PECs can be controlled by external parameters such as the ionic strength, the pH of the medium or the temperature. Therefore, such complexes should be of great interest as potential carrier systems for drugs, enzymes, or DNA because charged species can easily be integrated into the complex particles. 

Fig. 4a, b. Effect of the structure of the polycation component on the yield of polyelectrolyte complexes, (a) Pendant-type polycation (QPVP)-NaSS (b) Integral-type polycation (3 X)-NaSS ... 

Fig. 45 a, b. Time dependence of the aggregation process of the polyelectrolyte complex composed of integral-type polycation (2X)-poly(methacrylic add) (PMAA) (x 125). (a) 4 days, (b) 7 days, (c) 14 days after mixing... 

Fig. 50 a, b. Higher-order structure of aggregates of a polyelectrolyte complex of poly(methacry-lic acid) (PMAA) and integral-type polycation (2X), (a) Optical micrograph, (b) polarized light micrograph... 

A large number of macromolecules complementary to PMAA, namely polyvinylpyrrolidone, polyvinylpyridine, polyacrylamide, poly(vinyl alcohol), poly(ethylene oxide), oligoethylenimine, poly(sodium styrene sulfonate), polycations of the integral type ionen (2X) were used as P2 and P3. The pH of the media strongly influences the studied reactions of complex formation. For example, in PVPy + PVP + PMAA or OEI + PEO + PMAA systems in the add region, where weak polybases are completely protonized and PMAA does practically not dissodate, complexes with hydrogen bonds (PMAA-PVP or PMAA-PEO) are formed. In neutral medium weak polybases are partially ionizated and polyelectrolyte complexes (PMAA-PVPy, PMAA-OEI) are generated. In the alkaline medium formation of complexes has not been observed. 

H. Hoffmann, O. El-Seoud, G. Huber and R. Bocher, Polyelectrolyte-Surfactant-Complexes, in Integration of Fundamental Polymer Science and Technology (eds. P. J. Lemstra and L, A. Kleintjens), Elsevier Applied Science, London, 1988, Vol. 2, p. 317. 

The so-called product reactant Ornstein-Zernike approach (PROZA) for these systems was developed by Kalyuzhnyi, Stell, Blum, and others [46-54], The theory is based on Wertheim s multidensity Ornstein-Zernike (WOZ) integral equation formalism [55] and yields the monomer-monomer pair correlation functions, from which the thermodynamic properties of the model fluid can be obtained. Based on the MSA closure an analytical theory has been developed which yields good agreement with computer simulations for short polyelectrolyte chains [44, 56], The theory has been recently compared with experimental data for the osmotic pressure by Zhang and coworkers [57], In the present paper we also show some preliminary results for an extension of this model in which the solvent is now treated explicitly as a separate species. In this first calculation the solvent molecules are modelled as two fused charged hard spheres of unequal radii as shown in Fig. 1 [45],... 

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