Polyelectrolytes ion-exchange resins

Amberlite. Trade name for resorcinol type resins used for wood adhesives and manufd by the Rohm Haas Co, Phila 5,Pa. Also a trade-mark name for insoluble crossed-linked polyelectrolytes (ion-exchange resins). Used for water conditioning and other purposes... 

Polymers of linear or network structure with ionic groups which by addition of the appropriate counterions can be ionically cross-linked. A copolymer of ethylene and acrylic acid is used as a compatibilizer in polyamide blends. Converted to ethylene-zinc acrylate copolymer, Surlyn M jg y gd as packaging film. Other ionic polymers are applied as polyelectrolytes, ion exchange resin, etc. 

The structures of these ylide polymers were determined and confirmed by IR and NMR spectra. These were the first stable sulfonium ylide polymers reported in the literature. They are very important for such industrial uses as ion-exchange resins, polymer supports, peptide synthesis, polymeric reagent, and polyelectrolytes. Also in 1977, Hass and Moreau [60] found that when poly(4-vinylpyridine) was quaternized with bromomalonamide, two polymeric quaternary salts resulted. These polyelectrolyte products were subjected to thermal decyana-tion at 7200°C to give isocyanic acid or its isomer, cyanic acid. The addition of base to the solution of polyelectro-lyte in water gave a yellow polymeric ylide. 

Ionic conductivity can be found in polyelectrolytes such as the salts of polyacrylic acid, sulfonated polystyrene or quaternized polvamines (ion-exchange resins). When dry, these materials have low conductivities. However, in tiie presence of small amounts of polar solvents or water—some of these polyelectrolytes are somewhat hygroscopic electrical conductivity can be observed. The currents are earned by ions (protons, for instance). Such systems can only be used in cases where very small currents are expected. Large currents would result in observable electrochemical changes of the materials, In applications as antistatic electricity coatings, conductivities of 10-b ohm-1 cm-1 are sufficient,... 

In ion exchange, the aqueous phase ions are replaced with H and OH ions. If the aqueous phase ions are in equilibrium with the adsorbed ions, their removal from the aqueous phase causes desorption of the adsorbed ions to maintain the equilibrium until all of the adsorbed ions have been removed. In practice, this removal is quantitative (2-5). Ion exchange is rapid and easily carried out however, commercial ion exchange resins contain leachable polyelectrolytes which adsorb on latex particle surfaces these polyelectrolytes can be removed only by an arduous purification process (2-5). 

In addition to above phenomena, there is the sizable contribution of hydrophobic effects in our nanoparticulate system. As the opposite charges of interacting molecules are neutralized, and hydrophobicity rises, the particle is instantaneously formed. This is supported by our observations on the effect of ionic strength (Fig. 18), leading to an enhancement of release when the salt concentration is lowered. Hydrophobic interactions, in addition to ionic forces, were identified as an important mechanism for drug release from ion exchange resin [64], from the CT/TPP complex [62] and from theoretical calculations of forces involved in the assembly of polyelectrolytes [65]. 

Polyelectrolytes useful as ion-exchange resins have been prepared by beating a mixture of acrylonitrile, acetone, formaldehyde, and sodium bisulfite in a strongly alkaline aqueous solution and then saponifying the resulting polymer. 

Most of the ion-exchange resins consist of polyions. A typical one is also the most well known Nafion, the structure of which is shown in Fig. 2.77 the figure also shows the structure of some proteins (these are often polyelectrolytes). 

Alternatively the molecular models for linear and crosslinked polyelectrolytes (including ion exchange resins) interpret the swelling... 

Major polymer applications dispersants for pigments and fillers, thickeners, toothpaste, hydraulic fluids, ion exchange resins, binder for ceramic, dental cements, polyelectrolytes... 

Traditionally, soil humic substances have been defined by the fact they are soluble in 0.1 N NaOH. Aquatic humic substances, however, are operationally defined as polyelectrolytic acids that can be isolated from water by sorption onto XAD or weak base-ion exchange resins, for example (Thurman 1985). They are nonvolatile, have molecular weights from about 500 to 5000 g/mol, and a molar composition of about 50% C, 4 to 5% H, 35 to 40% O, and 1% N. 

This is not to say that more highly ionized polymers, such as conventional polyelectrolytes, are not of technological importance and interest. In fact, just the opposite is true. Polyelectrolytes have historically been utilized as ion-exchange resins, but a number of novel applications such as cements, gels, and encapsulation membranes are under development. Several applications of these materials, such as polyelectrolyte complexes and ionic biopolymers, are also included in this review. 

Ionomers are certainly not the only useful support for transition metals and ions. Indeed, inorganic oxides, such as silica, zeolites and aluminas, are the most widely used at present (13). Among the organic polymeric supports now used, the most closely related to the ionomers are the well known ion-exchange resins. While they are polyelectrolytic, as are the PFSA and PSSA ionomers, they are not thought to possess the potentially useful morphological properties of ionomers. 

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