Polyacrylate polyanions

FIGURE 11. The CSR of barium sulfate as affected by polyacrylate polyanions. The particle spin rate when driven by a rotating field at 600 kHz is seen to be affected even by very dilute solutions. 

Although all divalent ions precipitate PAA when the degree of dissociation, a, approaches 10, there are differences when a = 0-25 (Figure 4.11). Small amounts of barium and calcium ions precipitate PAA at this low a value, whereas magnesium ions do not. These differences are not to be attributed to differences in the amounts of counterions bound, for condensation theory (Section 4.2.3) predicts that all divalent counterions are bound to polyanions to the same extent (Imai, 1961). Therefore, differences must arise from differences in solubility between the various polyacrylates. At low degrees of neutralization barium polyacrylate has low solubility, while magnesium polyacrylate is very soluble. This is related to the extent of disruption of hydration regions as cations are bound to polyions. 

Small counterions (gegenions) ensure electroneutrality. For example, the sodium salt of polyacrylic acid is ionized in solution to form polyanions and the corresponding number of sodium cations ... 

It seems, however, that only polyanions are chiefly concerned in the interferon induction. Further polymers having anionic groups have been investigated besides poly(nucleic acid)s and co-(cyclopolymers) 8, for which a partial hydrolysis of the anhydride moiety is supposed. Thus, poly(vinylsulfonate)s or polyacrylates have been found to be active, but, polymethacrylates inactive. It has been shown that in the case of acrylic acid copolymers the molecular weight is also of importance in addition to the structure of the polymer chain and the fraction of carboxy groups. The influence of these various parameters has been discussed in detail by De Somer (45). 

A commercial assay is performed on an automated analyzer that uses a soluble reagent consisting of dihydroxy-boronate coupled to high molecular weight polyacrylic acid. GHb binds to the boronate. The polyanionic-glycated hemoglobin affinity complex attaches by electro-... 

Flocculation experiments in the presence of anionic polyelectrolytes (polyacrylate-PAA) and Ca2+ ions were carried out by Jasmund and Lagaly [19], The aggregation of kaolin particles is determined by the interaction between the polyacrylate and Ca2+ and occurs at a certain concentration ratio of Cct/cPAA. Polyanion molecules that were not covered with Ca2+ ions were only adsorbed at the edges, whereas polymer molecules covered with Ca2+ could adsorb at the basal faces of the kaolin platelets and can cause a face-to-face association. 

Nevertheless we have chosen an alternative approach microencapsulation using synthetic polyacrylates which may be stronger and more biocompatible (or at least have a more reproducible biocompatibility). Most of the effort has been with a particular water insoluble synthetic copolymer (HEMA-MMA), although other polyacrylates (water soluble or insoluble) have been used. In general, two approaches have been used complex coacervation with water soluble polycations and polyanions to generate an insoluble complex and simple coacervation with a water insoluble polymer precipitated from an organic solvent. 

A comparative study has been reported on the efficiency of different anionic ligands for the formation and stabilization of lr(0) nanoclusters. The investigated anions include the polyanions P2WisNb3062 A SiW9Nb3O40, C6Hs07 (citrate ), [-CH2-CH(C02 ) ], (polyacrylate ), and P309 (trimetaphosphate), and the common monoanions Oac, CP, and They have been evaluated according to five criteria their ability... 

A new method of enzyme immobilization in a polyion complex has been proposed by Uragami et An enzyme-immobilized polyion complex membrane was prepared by ultraflitrating a mixture consisting of quar-ternized chitosan (q-Chito) as a polycation, sodium polyacrylate (PAANa) as a polyanion and enzyme in an aqueous NaBr solution. 

Synthetic polyanions that have received considerable attention include pyran, polyacrylic acid, and poly(acrylic acld-alt-maleic anhydride) copolymer. More recently we have made an indepth study of several other copolymers of maleic anhydride [2,3]. 

Polyelectrolytes water-soluble polymers with many electrically charged groups per molecule. They form polyions on dissociation, either polyanions, as in the case of dissociated polyacrylic acid, or polycations, as in the case of protonated poly(vinylamine). They may also be polysalts, as in the case of the sodium salt of polyacrylic acid. 

Viscosity increases and gel formation in polyanion-cationic surfactant systems have also been reported, for example by Thalberg and Lindman (86) for hyaluronan and polyacrylate polymers in combination with alkyltrimethylammononium bromide surfactants. Similarly, viscosity increases and gel formation with polymers such as carboxymethyl cellulose (CMC) and CTAB at relatively low polymer-surfactant levels have been observed (87). 

Polyacrylamides Polyacrylamides Polyacrylate Polyamine Polyanionic cellulose... 

Among the examples of strongly charged polyelectrolyte gels one can mention polyanionic gel of sodium polyacrylate in water... 

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