Molecular weight of polyelectrolytes

Of the preponderance of small ions, the colligative properties of polyelectrolytes in ionising solvents measure counterion activities rather than Molecular weight. In the presence of added salt, however, correct Molecular weights of polyelectrolytes can be measured by membrane osmometry, since the small ions can move across the membrane. The second virial coefficient differs from that previously defined, since it is determined by both ionic and non-ionic polymer-solvent interactions. 

Abstract Investigations of alternate adsorption regularities of cationic polyelectrolytes a) copolymer of styrene and dimethylaminopropyl-maleimide (CSDAPM) and b) poly(diallyldimethylammonium chloride) (PDADMAC) and anionic surfactant - sodium dodecyl sulfate (SDS) on fused quartz surface were carried out by capillary electrokinetic method. The adsorption/desorption kinetics, structure and properties of adsorbed layers for both polyelectrolytes and also for the second adsorbed layer were studied in dependence on different conditions molecular weight of polyelectrolyte, surfactant and polyelectrolyte concentration, the solution flow rate through the capillary during the adsorption, adsorbed layer formation... 

These results show more clearly than Fq. (8.126)-of which they are special cases-the effect of charge and indifferent electrolyte concentration on the osmotic pressure of the solution. In terms of the determination of molecular weight of a polyelectrolyte by osmometry. ... 

The efficiency of flocculation of these polyelectrolytes was investigated at different pH and polymer concentrations, valency of cations, and weight-average molecular weight of the polymer. The results are shown in Figs. 12-16,... 

Polydispersity of molecular weights of heparin was recognized in early studies (reviewed in Refs. 9 and 183). However, the polyelectrolyte nature and heterogeneity of charge distribution have hampered accurate determinations of molecular-weight distribution. 

Values found for the molecular weight of deoxyribonucleic acids also vary considerably, but probably lie between 1.0 X 106 and 4.4 X 106. Various difficulties encountered in making such measurements have been discussed by Jordan,244 and it is probable that more reliable information will be obtained only when the behavior of polyelectrolytes in general is better understood. Certain of the techniques used are useful in detecting differences between different nucleic-acid preparations, but the discrepancies between the values given by different methods of measurement appear to vary with the degree of polymerization.246... 

Wolfert MA, Seymour LW. Atomic force microscopic analysis of the influence of the molecular weight of poly(L)lysine on the size of polyelectrolyte complexes formed with DNA. Gene Ther 1998 3(3) 269-273. 

The Wessling and Zimmerman aqueous precursor route is illustrated in Scheme 38 [156]. Here, a bis(halomethyl)monomer is reacted with dimethyl-sulfide and subsequent treatment with base affords the high molecular weight precursor polyelectrolyte 31. Due to the instability of 31, polymerization must be carried out at low temperatures (<4 °C) to avoid thermal elimination of the polyelectrolyte. Precursor polymer 31 can be stored in solution with refrigeration, and its shelf life can be increased by the addition of a small amount of pyridine. Precursor polymer 31 can be processed into highly oriented, free-standing films or fibers that can subsequently be converted to PPV with the elimination of gaseous dimethylsulfide and HCl at 200 °C. 

In two articles, J. Cesarano HI et al. [23, 24] described the stability of aqueous a-alumina suspensions stabilised with PMAA and PAA polyelectrolytes. The powders used were AKP-20 with a mean particle diameter of 0.52 pm and a surface area of 4.5 m2/g and AKP-30 as described above. The electrolytes used were the Na-salt of PMAA with an average molecular weight of 15000 g/mol and PAA of various molecular weights (1800, 5000 and 50 000 g/mol). The structural formulas of the polymers are shown in Figure 5. 

In this paper we investigate the process of alternate adsorption of cationic polyelectrolyte and anionic surfactant, structure and properties of adsorbed layers depending on different factors (molecular weight of PE, concentration of polyelectrolyte and surfactant, adsorbed layer formation time, the flow rate of the solution) by measuring potential and streaming current using the capillary electrokinetic method. 

The polyelectrolytes used in this study are displayed in Table 1. Hydrophobic flexible polyelectrolyte molecules of poly(methacryloyloxyethyl dimethylbenzylammonium chloride) (PMBQ) with a molecular weight of 4.2 Mio g/mol was synthesized by free radical polymerization in water solution as described elsewhere [18,19], Poly(so-dium styrenesulfonate) (PSS) with molecular weight of 70 000 g/mol was purchased from Aldrich and was used without further purification. Water purified and deionized (reverse osmosis followed by ion exchange and filtration) by means of Milli-RO 5Plus and Milli-Q Plus systems (Millipore GmbH, Germany) was used as a solvent. 

Incorporated HRP into polyelectrolyte complexes with chitosan of different molecular weights (MW 5-150 kDa) The complex formed by 0.001% chitosan with a molecular weight of 150 kDa was most stable when immobilized on foamed polyurethane, it retained at least 50% of the initial activity for 550 days [43]... 

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