Electric polarizabilities of polymers

Weill G, Hornick C. Electric polarizability of rigid polyelectrolytes. In Seleny E, ed. Charged and Reactive Polymers, Volume I. Poly electrolytes. Dordrecht Reidel, 1974 277-284. 

Washizu H, Kikuchi K. Anisotropy of the electrical polarizability of a model DNA fragment in aqueous salt solution. Rep Progr Polym Phys Japan. In press. 

Figure 7.7a shows that the electrical properties of polymer complex paper sheets were greatly influenced by the type of anion of ferric salt used for complex formation, whereas the Fe[HI] cation of FeCls greatly improves the e" of produced sheet, compared with that resulted from Fe[HI] of Fe[N03]3. These results reverse to some extent the trend of mechanical properties [Fig. 7.8a, Table 7.13]. The latter complex provided greater strength properties of produced paper sheet. This observation refers to higher bonded OH groups of cellulose pulps, and consequently, less oscillation and polarizability of OH group occur.

In this work, we address to the first point our objectives were to explore the modifications of the electrical double layer and hydrodynamic properties of a jS ferric hydrous oxide colloid in aqueous media, interacting with non-hydrolyz polyac lamide, a neutral polymer. The j8 ferric hydrous oxide particles are ellipsoidal shaped particles and the electrical double layer features can be determined through the electrical polarizability of the ellipse. Electro-optical determinations were complemented by measuring the electrophoretic mobility at various polymer coverage. 

The dielectric constant of a polymer (K) (which we also refer to as relative electric permittivity or electric inductive capacity) is a measure of its interaction with an electrical field in which it is placed. It is inversely related to volume resistivity. The dielectric constant depends strongly on the polarizability of molecules tvithin the polymer. In polymers with negligible dipole moments, the dielectric constant is low and it is essentially independent of temperature and the frequency of an alternating electric field. Polymers with polar constituents have higher dielectric constants. When we place such polymers in an electrical field, their dipoles attempt... 

Experimental and theoretical results are presented for four nonlinear electrooptic and dielectric effects, as they pertain to flexible polymers. They are the Kerr effect, electric field induced light scattering, dielectric saturation and electric field induced second harmonic generation. We show the relationship between the dipole moment, polarizability, hyperpolarizability, the conformation of the polymer and these electrooptic and dielectric effects. We find that these effects are very sensitive to the details of polymer structure such as the rotational isomeric states, tacticity, and in the case of a copolymer, the comonomer composition. 

We have shown in this paper the relationships between the fundamental electrical parameters, such as the dipole moment, polarizability and hyperpolarizability, and the conformations of flexible polymers which are manifested in a number of their electrooptic and dielectric properties. These include the Kerr effect, dielectric polarization and saturation, electric field induced light scattering and second harmonic generation. Our experimental and theoretical studies of the Kerr effect show that it is very useful for the characterization of polymer microstructure. Our theoretical studies of the NLDE, EFLS and EFSHG also show that these effects are potentially useful, but there are very few experimental results reported in the literature with which to test the calculations. More experimental studies are needed to further our understanding of the nonlinear electrooptic and dielectric properties of flexible polymers. 

Dielectric polarization is the polarized condition in a dielectric resulting from an applied AC or DC field. The polarizability is the electric dipole moment per unit volume induced by an applied field or unit effective intensity. The molar polarizability is a measure of the polarizability per molar volume thus it is related to the polarizability of the individual molecules or polymer repeat unit. 

The induced dipole moment of a polymer in an electric field is proportional to the strength of the field, and the proportionality constant is related to the polarizability of the atoms in the polymer. The dielectric properties of polymers are affected adversely by the presence of moisture, and this effect is greater in hydrophilic than in hydrophobic polymers. 

For a long time the finite oligomer approach was the only method available for determining linear and nonlinear polarizabilities of infinite stereoregular polymers. Recently, however, the problem of carrying out electronic band structure (or crystal orbital) calculations in the presence of static or frequency-dependent electric fields has been solved [115, 116]. A related discretized Berry phase treatment of static electric field polarization has also been developed for 3D solid state systems... 

Although in our simulations, solvent convection is suppressed [35,39], characteristic features of the electric properties of polyelectrolytes in salt-free aqueous solutions are reproduced. The anisotropy of the electrical polarizability Aa of DNAs in salt-free aqueous solution increases on dilution of the polymer concentration and is proportional to the second power of the molecular weight. 

In Figure 10, longitudinal and transverse partial electrical polarizability pairs, aL(n) and aT(n), determined for a 64 base-pair DNA at various polymer concentrations are plotted against the number of contributing counter-... 

Figure 12 shows polymer concentration cP dependence of the anisotropy of the electrical polarizability Aa of a 64/128 base-pair DNA fragment. Aa increases on dilution of polymer concentration. Experimentally, Aa is determined via measurement of the Kerr constant of the polyelectrolyte solutions, and in the case of rodlike polyelectrolytes both quantities are proportional to each other. It has been observed that the Kerr constant of polyelectrolytes in salt-free aqueous solutions increases on dilution [46,47], This behavior of the Kerr constant is one of the characteristic properties of polyelectrolytes in salt-free aqueous solutions whose reproduction we have succeeded in by computer simulation. The figure also indicates that Aa is... 

FIG. 12 Polymer concentration cP dependence of the anisotropy of the electrical polarizability Aa of a 64/128 base-pair DNA fragment. 

Our first attempt to apply electro-optics in the investigation of the adsorption of neutral polyacrylamide on kaolinite particles was in 1988 [4,5]. Several electro-optical parameters were used to follow the adsorption of polymer on colloid particles—the amplitude of the electro-optical effect, the critical frequency of relaxation of the low- and high-frequency effects, the electro-optical decay time after the switching off of the electric field. Variations in these parameters with concentration of the added polymer give information on the particle electric polarizability, the thickness of the adsorbed polymer layer, the size of aggregates that appear in the suspension due to flocculation [4-10], etc. 

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