Polyelectrolytes cationic

There are three types of polyelectrolytes cationic, anionic and non-ionic. Sometimes cationic polymers are added as a coagulant. The polymers bring the system to the isoelectric... 

A different way was chosen to predict the behavior of the mixtures anionic polyelectrolyte/cationic surfactant [32, 33]. The formal Flory presentation is maintained but the interaction parameter, is assumed to give a complete representation of all types of interactions (including electrical). In these conditions, X, is a more or less adjustable parameter with values which can be out of the scope of the original Flory s definition. An important point, well developed... 

Fig. 3 Confocal microscopy images of gel particles composed of a polyelectrolyte (cationically modified hydroxyethyl cellulose (JR-400 ) and two different types of surfactants (cetyltri-methylammonium bromide, CTAB, and sodium perfluorooctanoate, FC7). The resulting gel particles can assume two types of morphologies depending on the surfactant concentration a smooth hollow particle with dense thin gel shell for lower concentrations, and b gel particle with sparse thick shell, and a gel corona for higher concentrations. Reprinted from Lapitsky and Kaler [51]. Copyright (2004), with permission firom Elsevier...

Polyelectrolyte complex membranes are phase-inversion membranes where polymeric anions and cations react during the gelation. The reaction is suppressed before gelation by incorporating low molecular weight electrolytes or counterions in the solvent system. Both neutral and charged membranes are formed in this manner (14,15). These membranes have not been exploited commercially because of then lack of resistance to chemicals. 

Monovalent cations are good deflocculants for clay—water sHps and produce deflocculation by a cation exchange process, eg, Na" for Ca ". Low molecular weight polymer electrolytes and polyelectrolytes such as ammonium salts (see Ammonium compounds) are also good deflocculants for polar Hquids. Acids and bases can be used to control pH, surface charge, and the interparticle forces in most oxide ceramic—water suspensions. 

SG sols were synthesized by hydrolysis of tetraethyloxysilane in the presence of polyelectrolyte and surfactant. Poly (vinylsulfonic acid) (PVSA) or poly (styrenesulfonic acid) (PSSA) were used as cation exchangers, Tween-20 or Triton X-100 were used as non- ionic surfactants. Obtained sol was dropped onto the surface of glass slide and dried over night. Template extraction from the composite film was performed in water- ethanol medium. The ion-exchange properties of the films were studied spectrophotometrically using adsorption of cationic dye Rhodamine 6G or Fe(Phen) and potentiometrically by sorption of protons. 

Polyelectrolytes are classified into three main groups nonionic, anionic, and cationic depending upon the nature of the residual charge on the polymer in aqueous solution as shown in Table 1. 

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,... 

Meisel etal. [18-20] were the first to investigate how the addition of a polyelectrolyte affects photoinduced ET reactions. They found that charge separation was enhanced as a result of the retardation of the back ET when poly(vinyl sulfate) was added to an aqueous reaction system consisting of tris(2,2 -bipyridine)ruthenium(II) chloride (cationic photoactive chromophore) and neutral electron acceptors [21]. More recently, Sassoon and Rabani [22] observed that the addition of polybrene (a polycation) had a significant effect on separating the photoinduced ET products in an aqueous solution containing cir-dicyano-bis(2,2 -bipyridine)ruthenium(II) (photoactive donor) and potassium hexacyano-ferrate(III) (acceptor). These findings are ascribable to the electrostatic potential of the added polyelectrolytes. 

Cationic Polyelectrolytes Containing Nucleic Acid Bases.139... 

Cationic polyelectrolytes containing imidazole groups have been investigated by some researchers. Morawetz et alU4 first found that a cationic polymer, poly (l-vinyl-3-ethylimidazolium iodide), 65 (PQMelm), enhanced the hydrolyses of the negatively charged esters, i. e. NABA and 4-acetoxy-3-nitrobenzenesulfonate 66 (NABS). At intermediate pH, a large catalytic effect was observed and this was... 

---