Cationic polyelectrolytes, characteristics

In a related application, polyelectrolyte microgels based on crosslinked cationic poly(allyl amine) and anionic polyfmethacrylic acid-co-epoxypropyl methacrylate) were studied by potentiometry, conductometry and turbidimetry [349]. In their neutralized (salt) form, the microgels fully complexed with linear polyelectrolytes (poly(acrylic acid), poly(acrylic acid-co-acrylamide), and polystyrene sulfonate)) as if the gels were themselves linear. However, if an acid/base reaction occurs between the linear polymers and the gels, it appears that only the surfaces of the gels form complexes. Previous work has addressed the fundamental characteristics of these complexes [350, 351] and has shown preferential complexation of cationic polyelectrolytes with crosslinked car-boxymethyl cellulose versus linear CMC [350], The departure from the 1 1 stoichiometry with the non-neutralized microgels may be due to the collapsed nature of these networks which prevents penetration of water soluble polyelectrolyte. 

The base hydrolyses of these substrates were enhanced by the addition of cationic polyelectrolyte and polysoap. Saturation type kinetics were observed and the values of rate constants for the uncatalyzed and catalyzed reactions are given as well as the values for the association constant. The results suggest that the hydrophobic interactions play a major role in the hydrolysis enhancements of the neutral and charged substrates, and that these polymeric micelles can provide both the characteristics of polyelectrolytes and micelles and thus give higher rate enchancements. 

Cationic water-dissolved polyelectrolytes find wide application in industry different fields, namely, for the ecological problems solution [34]. For understanding these polymers action mechanism and synthesis processes it is necessary to define their molecular characteristics and water solutions properties too [35]. Therefore, the authors [36] performed description of cationic polyelectrolytes in solution behavior within the framework of fractal analysis on the example of copolymer of acrylamide with trimethylammonium methacrylate chloride (PAA-TMAC). The data [35] for four copolymer PAA-TMAC with TMAC contents of 8, 25, 50 and 100 mol. % were used. In Ref [35] the equations Maik-Kuhn-Hou-wink type were obtained, which linked intrinsic viscosity [q] (the Eq. (1)) and macromolecular coil gyration radius with average weight molecular weight of polymer [35] ... 

In previous publications on the interaction between cationic polyelectrolytes and anionic surfactants, we have described the solu-bility, surface tension, electrophoresis, and dye solubilization characteristics of their mixtures. We also reported briefly on their viscosity behavior. ... 

The viscosity and non-Newtonian flooding characteristics of the polymer solutions decrease significantly in the presence of inorganic salts, alkali silicates, and multivalent cations. The effect can be traced back to the repression of the dissociation of polyelectrolytes, to the formation of a badly dissociating polyelectrolyte metal complex, and to the separation of such a complex fi"om the polymer solution [1054]. 

It should be pointed out that the addition of substances, which could improve the biocompatibility of sol-gel processing and the functional characteristics of the silica matrix, is practiced rather widely. Polyethylene glycol) is one of such additives [110— 113]. Enzyme stabilization was favored by formation of polyelectrolyte complexes with polymers. For example, an increase in the lactate oxidase and glycolate oxidase activity and lifetime took place when they were combined with poly(N-vinylimida-zole) and poly(ethyleneimine), respectively, prior to their immobilization [87,114]. To improve the functional efficiency of entrapped horseradish peroxidase, a graft copolymer of polyvinylimidazole and polyvinylpyridine was added [115,116]. As shown in Refs. [117,118], the denaturation of calcium-binding proteins, cod III parvalbumin and oncomodulin, in the course of sol-gel processing could be decreased by complexation with calcium cations. 

For this study, humic and fulvic materials obtained from a small glaciated bog were separated into five size fractions by using hollow-fiber ultrafiltration techniques. The major cations associated with these organics are reported as a measure of the natural binding capacity of each size range. The structural characteristics and carboxylate content of each group were studied by CIR spectroscopy the results are compared with those obtained by traditional Fourier transform infrared techniques. To aid in spectral interpretation, results were compared to those for selected model polyelectrolytes and simple acids. 

Pradip, Premachandran, R.S., and Malghan, S.G., Electrokinetic behaviour and dispersion characteristics of ceramic powders with cationic and anionic polyelectrolytes, Bull. Mater. Sci, 17, 911, 1994. 

As discussed in the Introduction to this paper, different viscosity versus concentration behavior is observed for SFS solutions in toluene/methanol and in DMF. Folyelectrolyte behavior is observed only in the latter solvent. The ESR spectrum of a 2.65 mole % Mn-SPS in these two solvents was studied at various concentrations. For both lvents, the hyperfine structure characteristic of isolated Mn ions was observed in very dilute solutions and at concentrations for which Lundberg and Phillips(10) observed strong intermolecular interactions. The ESR data indlcat that in dilute solution in both DMF and toluene/methanol, the Mn exists mainly as Isolated cations. In addition, the IR spectra indicated that the cation is removed from the anion to a similar degree in both solvents. Yet, a polyelectrolyte effect is observed experimentally only in DMF solutions. Although there was some dipole-dipole broadening of the toluene/methanol spectrum, the line width and the g-factor (g 2,000) in both cases were ldent fal. The g-factor of 2.000 is characteristic of an isolated Mn in solution ). 

Water-soluble probes have also been reported to undergo marked changes in their fluorescence characteristics when dispersed in polyelectrolyte solutions [18,52,61,72-78]. For example, the cationic dye, auramine O (AuO) is virtually nonfluorescent in aqueous solution but an increase in intensity is observed in the presence of PMAA at low pH as a result of enhanced binding in the hypercoiled state [72,73,75,78]. On neutralization, the fluorescence from AuO decreases as the compact structure breaks down forming the expanded state and the probe is released to the aqueous phase [52]. In a recent extension of this theme, the sensitivity of the emission spectrum of AuO to the environment in which it resides has been further exploited by covalently bonding the dye to PMAA [61]. Figure 2.1 shows the... 

A flocculation process. This serves to harvest the bacterial cells, i.e. remove cells from the growth medium, and ultimately to form the support matrix. This stage in the process is achieved by the sequential addition of cationic and anionic polyelectrolytes. The two polyelectrolytes used are capable of forming a polysalt complex and it is believed that this complex structure, in which the bacterial cells are embedded, gives rise to the product s robust physical characteristics whilst allowing the desired enzyme performance. 

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