DSC analyses of bound water in the microdomains of interpolymer complexes

Bound water in polymers and polymer complexes was analyzed quantitatively by means of differential scanning calorimetry in a temperature range from −50 to + 20°C. The water molecules were bound to the polymer chains with different strength, as reflected in a shift of the melting temperature. The existence of non‐freezing water was also confirmed from the relation between the incorporated water content and the heat of fusion. About 0,3 to 0,6 g of water was revealed to exist as non‐freezing water in 1,0 g of the polyelectrolyte complexes. This amount varied with the structure of the polymers investigated. The melting temperature of bound water increases with increasing water content of the component polymers or polymer complexes. The number of bound water molecules per monomeric unit of the polymer is about 3 to 7, and decreases by complex formation. It is speculated from the obtained results that desolvation is accompanied with complex formation, but the solvated state is maintained largely in spite of a drastic decrease in segmental motion of the polymer chains in the polymer complexes.