Structure of charged polymer solutions

Polyelectrolytes in solution represent an important class of polymers. Much interest in polyelectrolytes occurs because many biological polymers are polyelectrolytes. In particular DNA and RNA are prototypical exam- 

Five parameters classify the main types of linear polyelectrolytes the fraction / of charged monomers, the strength of the Coulomb interaction normalized to ksT, A, the added salt concentration Cs, the polymer concentration c and of coiuse the chain length L. One other important quantity is the valence of the counterions or salt ions. For the most part only monovalent ions have been considered to date in simulations and theory. To completely understand polyelectrolytes requires studying the variation of each of these quantities which is a formidable task. The understanding of polyelectrolytes in solution is just beginning. While much work has been done on these systems, by no means is there a definitive understanding of their properties and structure. 

A is called the Manning ratio. The dimensionless Coulomb pair interaction is then 

Below we discuss the present status of the theory of polyelectrolytes. Some of the important experimental results with which there is simulation data to compare are also discussed. We do not mention experiments such as viscosity measurements since no simulation has calculated such quantities. 

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Transition Temperature. The order-disorder transition temperature mid-point T is also determined both by the environment - salinity, pH value, and the nature of the ions in solution, and the structure of the polymer - charge, pyruvate, succinate and acetate content. Most published work describes the low salinity behaviour of such polymers, and has shown that for xanthan, the transition temperature exceeds 100 C as the salinity exceeds about 1 per cent sodium chloride (10). 

For any practical application of polyelectrolyte brushes the influence of multivalent ions, hydrophobic ions, and other polyelectrolyte molecules present in a contacting solution on to the structure of the surface-attached layers or the cylindrical polyelectrolyte brushes are of utmost importance. In particular, study of the interaction of brushes with other polyelectrolyte molecules in solution might open an avenue for the understanding of interaction of proteins or other charged biomolecules such as DNA, as a special form of charged macromolecules, with charged surfaces. It has become clear that not only the influence of the surface on to the conformation of the protein, but also the influence of the protein on the structure of the polymer layer is important. 

Diinweg B, Stevens MJ, Kremer K (1995) Structure and dynamics of neutral and charged polymer solutions effects of long-range interactions. In Binder K (ed) Monte Carlo and molecular dynamics simulations in polymer science. Oxford University Press, New York, p 159... 

Structural descriptors at the secondary level (mesoscale) are topology and domain size of polymeric aggregates (persistence lengths and radius), effective length and density of charged polymer sidechains on the surface, properties of the solution phase (percolation thresholds and critical exponents, water structure, proton distribution, proton mobility and water transport parameters). Moreover, -point correlation fimctions could be defined that statistically describe the structme, containing information about surface areas of interfaces, orientations, sizes, shapes and spatial distributions of the phase domains and their connectivity [65]. These properties could be... 

Polymer nanofibers can be obtained by applying electrical force at the surface of a polymer solution. A charged jet is ejected to the tip of the needle, and the jet extends, bends, and then follows a looping and spiraling path due to the action of the electrical field. It becomes very thin, until it reaches the collector. Nanofibers thathave diameters from several nanometers to hundreds of nanometers can be obtained in the form of nonwoven fiber mats. The small diameters lead to a large surface-area-to-mass ratio, a porous structure with excellent pore interconnectivity, and extremely small pore dimensions. 

The effect of sodium hydroxide on the xanthan flow curves is more than that expected from the charge shielding mechanism observed with sodium chloride. One possible explanation of this effect is base-catalyzed fragmentation reactions [26,32]. Fragmentation reactions break the biopolymer backbone (cellulose-like structure) to smaller saccharide units. Consequently, the hydrodynamic radius of the biopolymer would decrease and the viscosity of the polymer solution would diminish. 

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