Polyelectrolyte shape

Gueron, M. Weisbuch, G. Polyelectrolyte theory. I. Counterion accumulation, site-binding, and their insensitivity to polyelectrolyte shape in solutions containing finite salt concentrations. Biopolymers 1980 19 353-382. 

M. Gueron and G. Weisbuch, Biopolymers, 19, 353 (1980). Polyelectrolyte Theory. I. Counterion Accumulation, Site-Binding, and Their Insensitivity to Polyelectrolyte Shape in Solutions Containing Finite Salt Concentrations. 

Two extreme types of polyanions can be distinguished. In the first, the main chain is flexible and can assume a large number of different conformations so that the overall shape of the ion depends on the solvent. In some solvents (called bad ), they are rolled up to form a relatively rigid random coil , while in others ( good ) the coil is more or less expanded. This type includes most synthetic polyelectrolytes such as the following acids ... 

Electric field-induced deformation of polyelectrolyte gels has attracted much attention because of the property of smartness. If the size and shape of gels can be controlled as we hope, this may open a new door for gel technology. In this Section, studies on electric field-induced deformation of gels will first be surveyed. 

It should be noted that the relationships between molar mass and retention volume for lignin sulfonates shown in Figures 3 and 4 are strictly only valid for the samples studied in these experiments because lignin sulfonates are polyelectrolytes and thus interact with each other and with the gel matrix of the column. The shape of the calibration curve is thus affected by, among other things, the size and concentration of the sample (2). Interactions between molecular species can be eliminated by eluting with a suitable electrolyte. 

The cell model is a commonly used way of reducing the complicated many-body problem of a polyelectrolyte solution to an effective one-particle theory [24-30]. The idea depicted in Fig. 1 is to partition the solution into subvolumes, each containing only a single macroion together with its counterions. Since each sub-volume is electrically neutral, the electric field will on average vanish on the cell surface. By virtue of this construction different sub-volumes are electrostatically decoupled to a first approximation. Hence, the partition function is factorized and the problem is reduced to a singleparticle problem, namely the treatment of one sub-volume, called cell . Its shape should reflect the symmetry of the polyelectrolyte. Reviews of the basic concepts can be found in [24-26]. 

Size and Shape of Collapsing Polyelectrolytes by Light Scattering... 

Spherical micelles are not the only association structure that is formed by polyelectrolyte block copolymers. With increasing hydrophobic block length there is a tendency to form block copolymer vesicles. A vesicle formed by PB-P2VP.HC1 is shown in the cryo-TEM image in Fig. 14a. The bilayer structure is clearly resolved which shows that block copolymer vesicles are structurally very similar to lipid vesicles. Vesicles can be also imaged by AFM (Fig. 14b) where they exhibit a characteristic outer rim because the interior solution of the vesicle has evaporated during sample preparation leaving a shape that resembles that of an empty football. Vesicles typically have diameters of 100-300 nm and a bilayer thickness of 10-20 nm. 

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