Polysalt formation

Alginate-poly(L-lysine) and alginate-chitosan are, by far, the most common polymer-polymer coacer-vation systems, with the former often pregelled, in bead form, with divalent cations such as calcium or barium. As Table 2 indicates, polysaccharides with a rigid structure are generally favored for polysalt formation. 

Complex formation between a polycation and a polyanion is also called polysalt formation or coacervation. If, for example, a solution of poly(sodium styrene sulfonate) (III) is added to an equimolar solution of poly(4-vinyl pyridinium hydrogen bromide), then a stoichiometric complex with respect to the side groups is formed, and this occurs at every mixing ratio (Figure... 

Polysalt formation, as described in the previous section, is a special case of titration of polyelectrolytes. These acid-base reactions also exhibit some special differences from the corresponding phenomena with regard to low-molar-mass compounds. 

Ionization, conformational transitions, electrolytic behavior, polysalt formation, etc. of the acid form of the styrene-MA and a-methylstyrene-MA copolymers have been extensively... 

In most cases polysalt formation can be excluded in examining the reason for the obtained resolutions, as most polymers can only bind basic racemic mixtures as salts. A reasonable explanation for the partial resolution of DL-mandelic acid (I) might be the formation of diastereomeric adsorbates. Also it seems that the resolution of DL-a-aminophenylacetic acid (VII) does not proceed via salt formation mainly. 

FIG. 4 Conductance in reaction mixtures and control solutions during complex formation between the polysalts NaPSS and PVBTAC1. (a) [NaSS] = [VBTAC1] = 10 3 N in salt-free solution, (b) [NaSS] = [VBTAC1] = 10 2 N in 10 2 N NaCl. (From Ref. 3b.)... 

Dautzenberg H, Linow KJ, Rother G. The formation of water-soluble polysalts. 6. Investigation of the stoichiometry of simplexes and of the preferential bonding from polymer mixtures. Acta Polymerica 1990 41(2) 98—102. 

Formation of at least part of the polysalt matrix from the acid-base components has been shown to reduce the efficiency of the polymerization process [19]. hi a study in which the application of the dental cure lamp was delayed for 20 min following mixing of the cement, the degree of conversion was found to be substantially reduced and the overall rate of polymerization to be lower than in systems that were irradiated immediately after mixing [ 19]. It is worth noting that conversion of HEMA to polymer is never particularly efficient in these systems, and that the maximum reported conversion in this study was only about 60%, and this was for a specific material, namely Fuji II EC (Fig. 7.2). 

Varma A J, (1979), Polysalt complex formation and catalysis by polyjcrown ethers), Ph.D. Thesis, State University of New York, College of Environmental Science Forestry, Syracuse, New York. 

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