ABSTRACT
The formation of macromolecular complexes in solution, depending on the intensity of polymer-polymer and polymer-solvent interactions, leads to the separation of complexes as a solid or liquid phase. Because Ch is a cationic polyelectrolyte, most studies on the macromolecular complexes of Ch are concerned with polyelectrolyte complexes (PECs). However, only a few articles dealt with the polyionic interaction between polysaccharides, until Kikuchi
Figure 1 Dependence of water solubility of half N-acetylated Ch on the molecular weight. (From Ref. 4.)
Figure 2 Effects of pH and ionic strength on intrinsic viscosity [g] of Ch solution: x, 0.050 mol/L;Ez, 0.075 mol/L;E, 0.100 mol/ L; n, 0.200 mol/L; ., 0.300 mol/L; z, 0.500 mol/L NaCl. (From Ref. 6.)
first reported the PEC containing Ch as a component [10]. Several reviews on PEC have been published so far [11,12]. The formation of PEC is governed not only by the nature of the individual polyelectrolyte components, such as characteristics of polyions (strong orweak), position of ionic sites, charge density, molecular weight, flexibility, functional group structure, hydrophilicity and hydrophobicity, and stereoregularity, but also by the reaction conditions, such as pH, ionic strength, polymer concentration, mixing ratio, and temperature. This, therefore, may lead to a diversity of physical and chemical properties of the complexes. PECs arise due to interactions between oppositely charged polymers and can be additionally stabilized through short-
range interactions such as hydrophobic interactions and hydrogen bonds.
