INTERPOLYMER COMPLEXES OF A GRAFT COPOLYMER WITH POLYELECTROLYTES ANDEQUIVALENT BLENDS OF BINARY HOMOPOLYMER COMPLEXES - A COMPARATIVE-STUDY OF THEIR STABILITY AND THERMODYNAMIC PARAMETERS

Interpolymer complexes of acrylamide/vinyl alcohol graft copolymers (A Am/VA) were prepared with two typical polyelectrolytes, e. g. poly(met hacrylic acid) (PMA) and poly(ethyleneimine) (PEI). The equivalent ble nds of the same composition as the graft copolymer complexes were also prepared by mixing stoichiometric portions of binary homopolymer comp lexes. The stability constant (K), degree of linkage (theta) and relat ed thermodynamic parameters (e.g. standard free energy change Delta G( 0), standard enthalpy change Delta H-0 and standard entropy change Del ta S-0) were determined for each system by using Osada's method. The c omparative study between graft copolymer complexes and equivalent blen ds indicated a considerable difference in these parameters. An interpr etation of this discrepancy was sought in terms of copolymer effect, n eighbouring group influence, and the nature of secondary binding force s upon interpolymer complexation.