Polyelectrolyte complexes water-soluble

Polyelectrolyte complexes Water soluble polymer blends... 

Kabanov, V.A. and Zezin, A.B. (1984) A new class of complex water-soluble polyelectrolytes. Macromol. Chem. Phys. Suppl., 6, 259-276. 

The kinetics of vinyl acetate emulsion polymeriza tion in the presence of alkyl phenyl ethoxylate surfactants of various chain lengths indicate that part of the emulsion polymerization occurs in the aqueous phase and part in the particles (115). A study of the emulsion polymerization of vinyl acetate in the presence of sodium lauryl sulfate reveals that a water-soluble poly(vinyl acetate)—sodium dodecyl sulfate polyelectrolyte complex forms, and that latex stabihty, polymer hydrolysis, and molecular weight are controlled by this phenomenon (116). 

Keywords Bio artificial pancreas, biomaterials, complex coacervation, immunoisolation, microencapsulation, polyelectrolytes, water soluble polymers. 

Polyion complex technique [40] is a unique method for immobilization of bilayer membranes with polymers. Water-insoluble complex is precipitated as the polyion complex when an aqueous solution of the charged bilayer membrane is mixed with a water solution of the counter charged polyelectrolyte. Stoichiometric ion pair formation is often found. Aging of the precipitate in a hot mixture kept above phase transition temperature of the bilayer membrane completes the ion exchange reaction [41], Chloroform solution of the polyion complex is washed by water several times to remove water soluble components [42]. 

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. 

Significant research has been directed toward the use of polyelectrolyte complexes as blood compatible materials. Several investigators found that water-insoluble polyelectrolyte complexes can suppress blood coagulation [487-490]. Davison and coworkers reviewed and studied the biological properties of water-soluble polyelectrolyte complexes [491] between quatemized poly(vinyl imidazole) or polyvinyl pyridine) and excess sulfonated dextran or poly(methacrylic acid). By forming complexes with a stoichiometric excess of anionic charge, a more compact conformation with anionic character was obtained. 

Aggregates like polyelectrolyte complexes having positive charges and hydrophobic domains show a broader optimum flocculation concentration range and are considered as new reactive nanoparticles [11-14], Thus, polycations with hydrophobic functionalities represent an interesting class of water-soluble associating polyelectrolytes relevant for controlled stabilization/flocculation of dispersions in numerous industrial applications. 

Izumrudov et al.145) reported non-equimolar water-soluble polyelectrolyte complexes composed of PMAA and quaternized poly(4-vinylpyridine) (poly(N-ethyl-4-vinylpyridinium bromide) QPVP). When the pH is increased after making the mixing ratio (expressed as the molar ratio of [QPVP]/ [PMAA]) equal to unity in the neutralization (a) of PMAA beyond a = 0.8, it is confirmed that an equimolar water-insoluble complex is formed. If the initial... 

Usually they distinguish two types of complexes polyelectrolyte-ionic SAS. Firstly, complexes in which only the part of polymer units is connected with SAS iones. Such complexes are soluble in water their solubility is determined by the presence of polymer units not connected with SAS ions. Secondly, the complexes in which all or almost all units of polymer chain are connected with SAS ions. Such complexes are insoluble in water and are precipitated. Schematically soluble and non-soluble complexes of polyelectrolyte-SAS (on the example of complexes of polycarbonic acids with alkyltrimethylammonium bromides) are presented in Figure 3. 

The formation of a water-soluble complex of poly(sodium acrylate) with 5,6 ionen bromide of 3 1 composition has been observed108. Its mass and size are independent of the complex origin and are equal to 660 x 103 and 33 nm respectively. The soluble complex presumably consists of the insoluble nucleus of the equimolar polyelectrolyte complex and adsorbed excess of poly(sodium acrylate) on its surface. The soluble polyelectrolyte complex dissociates at higher ionic strengths (0.05-0.1) whereas the insoluble equimolar complex in the core is still stable and precipitates from the solution. 

The water-insoluble PMAA-poly(N-ethyl-4-vinylpyridinium bromide)polyelectro-lyte complex (5 l) formed at pH < 4 becomes soluble if the excess PMAA in the polyelectrolyte complex is ionized110. The solubility of the polyelectrolyte complex is apparently connected with the appearance of high negative charges of the complex particles and is accompanied by a conformational transition of PMAA in excess. It has been proposed that the water-soluble polyelectrolyte complex consists of the nucleus formed by bound base and acid units. This structure is retained in solution due to unbound parts (sequences) of ionized PMAA. 

Davison, C.J. Smith, K.E. Hutchinson, L.E.F. O Mullane, J. Physical and biological properties of water soluble polyelectrolyte complexes. J. Bioact. Compat. Polym. 1990, 5 (3), 267-282. 

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