Electrolyte salts poly electrolytes

For poly electrolyte solutions with added salt, prior experimental studies found that the intrinsic viscosity decreases with increasing salt concentration. This can be explained by the tertiary electroviscous effect. As more salts are added, the intrachain electrostatic repulsion is weakened by the stronger screening effect of small ions. As a result, the polyelectrolytes are more compact and flexible, leading to a smaller resistance to fluid flow and thus a lower viscosity. For a wormlike-chain model by incorporating the tertiary effect on the chain... 

Exceptions occur in the case of polyelectrolytes where a, in the absence of added salts, may approach two. The difference arises here because at infinite dilution the charges cause the poly electrolyte chain to become nearly fully extended. 

We consider a system of n polyelectrolyte chains each of N segments, ric counterions, Uy ions of species y from dissolved salt, and solvent molecules in volume 17. The total charge on each poly electrolyte is Q assumed to be proportional to N. 

Therefore we expect Df, identified as the fast diffusion coefficient measured in dynamic light-scattering experiments, in infinitely dilute polyelectrolyte solutions to be very high at low salt concentrations and to decrease to self-diffusion coefficient D KRg 1) as the salt concentration is increased. The above result for KRg 1 limit is analogous to the Nernst-Hartley equation reported in Ref. 33. The theory described here accounts for stmctural correlations inside poly electrolyte chains. 

Batteries. Many 7t-conjugated polymers can be reversibly oxidized or reduced. This has led to interest in these materials for charge-storage batteries, since polymers are lightweight compared to metallic electrodes and liquid electrolytes. Research on polymer batteries has focused on the use of polymers as both the electrode and electrolyte. Typical polymer electrolytes are formed from complexes between metal-ion salts and polar polymers such as poly(ethyleneoxide). The conductivity is low at room temperature due to the low mobility of cations through the polymer-matrix, and the batteries work more efficiendy when heated above the glass-transition temperature of the polymer. Advances in the development of polymer electrolytes have included polymers poly(ethylene oxide) intercalated into layered silicates (96). These solid-phase electrolytes exhibit significantly improved conductance at room temperature. 

Figure 10.9 Conformation of a linear poly electrolyte depending on salt concentration. At high salt concentration they tend to from a dense random coil which changes to a more stretched conformation at low salt concentration. In addition, the conformation in the adsorbed state is indicated.

Kabanov, V.A., Zezin, A.B., Rogacheva, V.B. and Ryzhikov, S.V. (1982) Disproportionation of nonstoichiometric poly electrolyte complexes in water-salt solutions. Dokl. Akad. NaukSSSR, 267, 862-865. 

Consider a dilute suspension of polyelectrolyte-coated spherical colloidal particles (soft particles) in a salt-free medium containing counterions only. We assume that the particle core of radius a (which is uncharged) is coated with an ion-penetrable layer of polyelectrolytes of thickness d. The polyelectrolyte-coated particle has thus an inner radius a and an outer radius b = a + d (Fig. 6.4). We also assume that ionized groups of valence Z are distributed at a uniform density N in the poly electrolyte... 

In the preceding section, the remarkable salt concentration effect on the acid dissociation equilibria of weak polyelectrolytes has been interpreted in a unified manner. In this treatment, the p/( ,pp values determined experimentally are believed to reflect directly the electrostatic and/or hydrophobic nature of polyelectrolyte solutions at a particular condition. It has been proposed that the nonideality term (Ap/Q corresponds to the activity ratio of H+ between the poly electrolyte phase and the bulk solution phase, and that the ion distribution equilibria between the two phases follow Donnan s law. In this section, the Gibbs-Donnan approach is extended to the equilibrium analysis of metal complexation of both weak acidic and weak basic polyelectrolytes, i.e., the ratio of the free metal ion activity or concentration in the vicinity of polyion molecules to that of bulk solution phase is expressed by the ApAT term. In Section III.A, a generalized analytical treatment of the equilibria based on the phase separation model is presented, which gives information on the intrinsic complexation equilibria at a molecular level. In Secs. B and C, which follow, two representative examples of the equilibrium analyses with weak acidic (PAA) and weak basic (PVIm) functionalities have been presented separately, in order to validate the present approach. The effect of polymer conformation on the apparent complexation equilibria has been described in Sec. III.D by exemplifying PMA. 

Salt pumps, in aqueous solution, work according to this principle poly-electrolyte is added to a cell and the salt is driven out into the other one. After this, it is easy to get rid of the polyelectrolyte. 

Natural organic polyelectrolytes are some of the most active components of natural soil-water systems entering into physical and chemical reactions with practically all other components of the systems. Most pesticides are strongly sorbed by insoluble natural organic polyelectrolytes, such as humic acid. The soluble humic salts, however, may solubilize insoluble pesticides. Pesticides also enter into chemical reactions with natural organic poly electrolytes. The mechanisms of most of these interactions have not yet been elucidated. Elucidation will require isolation of well-defined, chemically and physically homogeneous natural polyelectrolyte fractions. 

Films of lithium triflate salt of [NP(0CH2CH20CH2CH20CH3) (MEEP) can be photochemically cross-linked. This inhibits slow loss of electrolyte from the cell. similar results are obtained from [NP[ (0CH2CH20)7R]2] (R=Me, CH2CH=CH2). °° The polymer electrolyte, MEEP/poly(propylene oxide), combined with several lithium salts has been employed as an electrolyte and conductivities have been... 

Species listed above (sodium salts) have been characterized in water and/or aqueous IMaCl solution in terms of Na counterion activity coefficient, heat of dilution, and heat of Cu ions binding. These experiments are part of a systematic investigation on the relationship between "charge-density" along poly-electrolyte chains and (metal] ion-binding, comparing experimental evidence with existing theories (J, 3). ... 

Poly(oxyethylene) combinations with various other comonomers [46], are of interest as solid polymer electrolytes after complex formation with Li(I) (complexation with Na(I), K(I), Mg(II), Ba(II), etc. has also been studied) [1,5,46-48]. The synthesis is carried out by direct interaction of the ligand and metal ions in solution or, if cross-linked poly(oxyethylene) is employed, by immersing the polymer ligand into a solution of the metal salt. Poly(oxypropylene), modified polysiloxanes, cross-linked phosphate esters and ethers [46,49,50], and structurally different ligands such as 2,5-dimercapto-1,3,4-thiadiazol-polyaniline [51] have also been used as polymer ligands, The developments in this field are reviewed in [46], In this review the segmental motion of Li(I) in a poly(oxyethylene) is described as shown in Fig. 5-4. 

Poly electrolyte Star Conformation in a Dilute Salt-Free Solution... 

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