Intrinsic viscosity of polyelectrolytes

Stigter, D, Ionic Charge Effects on the Sedimentation Rate and Intrinsic Viscosity of Polyelectrolytes. T7 DNA, Macromolecules 18, 1619, 1985. 

Branched polymers in good solvents Intrinsic viscosity of polyelectrolyte solutions... 

INTRINSIC VISCOSITY OF POLYELECTROLYTE SOLUTIONS 45 1.7 INTRINSIC VISCOSITY OF POLYELECTROLYTE SOLUTIONS 1.7.1 Role of Electrostatic Interactions... 

The highly nonlinear concentration dependence evident in Figure 1.9 makes determination of the intrinsic viscosity by extrapolation of tjsp/c data via Eqs. (1.24) and (1.25) impossible. Cohen and Priel [1990] report observing that linear concentration dependence is observed at concentrations substantially below Cmax. allowing determination of [ ]. Theoretical analysis [Nishida et al., 2001, 2002] suggests that the dominant contribution responsible for the appearance of the peak in the / sp/c versus c plots comes from the intermolecular electrostatic repulsions between polyions. Based on this idea, Nishida et al. [2002] propose a method to determine the intrinsic viscosity of polyelectrolyte solutions at very low ionic strength, by assuming additivity in the contributions of intra- and intermolecular interactions that is. 

Still the coil expansion and the intrinsic viscosity depend on the salt concentration, even for a linear curve progression. For this reason, intrinsic viscosities of polyelectrolytes should be always accompanied by the salt concentration that they were determined at. This is extremely important for the [/j]-M-relationships described in chapter 6. As one can see in Fig. 6.11 theses relationships change for the same polymer, depending on the salt concentration at which the intrinsic viscosity was determined. 

Flory, P.J. and Osterheld, J.E., Intrinsic viscosities of polyelectrolytes polyacrylic acid, /. Phys. Chem., 58, 653, 1954. 

While it may be argued that the retention data may show a salinity effect (compare Cores 52 and 55, Table 2), this effect appears smaller than other observations. For some systems, Holland and Eirich have shown the resistance factor to be directly related to the intrinsic viscosity. The effect of brine concentration on the intrinsic viscosity of polyelectrolytes has been shown to decrease with increasing ionic strength. Consequently, the lack of a significant brine effect on measured resistance factors is explainable by the... 

Nishida, K., Kaji, K., Kanaya, T, and Fanjat, N. 2002. Determination of intrinsic viscosity of polyelectrolyte solutions. Polymer 43 1295-1300. 

Pavlov, G. M., Gubarev, A. S., Zaitseva, I. L, and Sibileva, M. A. 2006. Determination of intrinsic viscosity of polyelectrolytes in salt-free solutions. Russ. J. Appl. Chem. 79 1407-1412. 

Antonietti M., Briel A., Fosrster S. Quantitative Description of the Intrinsic Viscosity of Branched. Polyelectrolytes. Macromolecules 1997, 30, 2700-2704. 

Poly(N-phenyl-3,4-dimethylenepyrroline) had a higher melting point than poly(N-phenyl-3,4-dimethylenepyrrole) (171° vs 130°C). However, the oxidized polymer showed a better heat stability in the thermogravimetric analysis. This may be attributed to the aromatic pyrrole ring structures present in the oxidized polymer, because the oxidized polymer was thermodynamically more stable than the original polymer. Poly(N-phenyl-3,4-dimethylenepyrroline) behaved as a polyelectrolyte in formic acid and had an intrinsic viscosity of 0.157 (dL/g) whereas, poly(N-pheny1-3,4-dimethylenepyrrole) behaved as a polyelectrolyte in DMF and had an intrinsic viscosity of 0.099 (dL/g). No common solvent for these two polymers could be found, therefore, a comparison of the viscosities before and after the oxidation was not possible. 

The PAA-PVP system in methanol and the PMAA-PVP system in DMF display the typical properties of polycomplexes, namely low values of intrinsic viscosity independent of the matrix molecular weight (for PVP with molecular weight of 50 MO and 560000, the intrinsic viscosity [ /], of PA A-PVP complexes in methanol is equal to 0.07 dl/g), the absence both of the concentration dependence of the reduced viscosity, and of the polyelectrolyte anomaly. 

Fig. 2. rV) Dependence of polyelectrolyte intrinsic viscosity (dl/g) on the d ree of neutralization a, in 0.1 JV NaCl. o, conventional PMA , isotactic PMA A, conventional PAA. (Barone, G., V. Crescenzi, F. Quadrifoguo, and V. Vi-TAGtiANo Conformation-dependent anomalies in the viscometric and poten-tiometric behaviour of poly(methacrylic acid) and poly(L-glutamic acid), Ric. Sd. 36, 447 (1966).] It is interesting to point out that the intrinsic viscosities of the conventional and isotactic PMA samples used in this work, which are difierent in 0.1 N NaCl, were found to be nearly identical in 2 N NaNO, and a = 1... 

For another synthetic ( conventional") vinyl polyelectrolyte, sodium polyacrylate, Takahashi and Nagasawa (42) have measured the intrinsic viscosity of a number of fractions under G conditions (1.056 N NaBr at 15° C) and report 11.0 as the characteristic ratio value of that polymer [using the value 0 — 2.87 10 for the universal parameter in equation (1)]. Both the polyvinylsulfonate and polyacrylate samples used by Eisenberg and Woodside and by Takahashi and Nagasawa were however of the conventional type, and thus composed of chains of unknown tacticity. This fact makes it more difficult to compare the experimental values with those dedudble from theories based on... 

CGE is suitable for the analysis of synthetic polyelectrolytes. Fast separations of high repeatability-when analyte interactions with the capillary wall are excluded-help to decrease separation time and solvent consumption compared with SEC. The only restriction is that CGE is only an analytical technique for small sample sizes. Selection of the optimal separation system with respect to molecular mass of the sieving polymer and its concentration is possible by applying simple rules and available data like intrinsic viscosity of potential sieving polymers. Non-UV-absorbing polyelectrolytes can be analyzed by applying indirect detection techniques. In various applications it has been shown that determination of molecular mass averages and molecular mass distribution is possible with CGE. 

Antonietti, M., Briel, A., and Forster, S., Quantitative description of the intrinsic viscosity of branched polyelectrolytes. Macromolecules, 30, 2700-2704 (1997). 

The intrinsic viscosity (rj) is a characteristic value of a single macromolecule in a given solvent and it is a measure of the hydrodynamic volume occupied by the polymer itself. It depends primarily on the molar mass (Mw), chain rigidity, and solvent quality. For anionic polyelectrolytes the presence of macroions and counterions in aqueous media causes coil expansion by intrachain electrostatic repulsion and extra dissipation of energy, thus explaining why the intrinsic viscosity of a polyelectrolyte can be higher than that of a neutral rodlike macromolecule of equal size. Thus, (rj) usually increases with an increase in the charge density of the macroion. 

Slagowski et al. (33) demonstrated the feasibility of HFIP as the SEC eluant for several polytetramethylene terephthalate polymers. Because polystyrene is not soluble in HFIP, no MW values were reported. In the same year Drott (7) used HFIP as SEC solvent for both nylons and polyesters. A polyelectrolyte effect had been observed for nylons but it was not a problem for polyesters. Drott also indicated that no polymer degradation occurred in HFIP by comparing the intrinsic viscosities of the initial and recovered PET samples. The direct calibration method was used by trial-and-error adjustment of the coefficients of a cubic polynomial until intrinsic viscosities of the samples calculated from SEC data (using the Mark-Houwink equation) agreed with experimentally measured values. 

In the past, a determination of an intrinsic viscosity for polyelectrolyte solutions even at very low salt concentrations was carried out with the empirical Fuoss equation. The increasing reduced viscosity at low polymer concentrations can be described with the following equation ... 

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