Theoretical and experimental studies of the phenomenon of complex coacervation have focused on the system in which oppositely charged polymeric polyions are mixed under conditions where: 1) each polyion is completely miscible with the solvent; 2) each polyion backbone can be treated as a random chain polymer; and 3) the charges on each polyion chain can be treated as distributed randomly in the solution, that is, as if independent of their residence on the polyion backbone chains. Under suitable conditions of pH and ionic strength, the system will demix, that is split into two phases, each of which contains both polyions, but with the two phases having markedly different total polyion concentrations. The gelatin-gelatin coacervation system provides a particularly good example of the effect of structural order on coacervation equilibrium. A stringent test of the effects of conformation, was to examine the phase separation using collagen as one of the polyions. A unique high charge density polyanion a phosphoprotein called phosphophoryn [PP], binds strongly to collagen because of ionic interactions. Since collagen monomers can be visualized directly in the electron microscope using rotary shadowing techniques, an attempt was made to examine the nature of the PP-collagen aggregates formed in the coacervate. In the dilute solution phase the aggregates are not electrically neutral, and the number of PP molecules associated with a single collagen molecule is variable and probably dependent on the initial mixing ratio. The concentrated aggregate phase grows to form huge aggregates which probably tend to become electrically neutral overall. The above behaviour is that predicted by the symmetrical aggregate model.
|Original language||English (US)|
|Number of pages||2|
|Journal||American Chemical Society, Polymer Preprints, Division of Polymer Chemistry|
|State||Published - Apr 1 1991|
ASJC Scopus subject areas
- Polymers and Plastics