Conductimetric and viscometric study of the macromolecular complex between poly(acrylic acid) and poly(vinyl pyrrolidone)

The intermacromolecular complex between poly(acrylic acid) (PAA) and poly(vinyl pyrrolidone) (PVP) was studied by means of conductimetry and viscometry. Conductimetry is shown to be a useful tool in the investigation of this kind of complex because the polyacid dissociation is suppressed in the presence of PVP. Near to stoichiometry there is a minimum in the viscosity-composition curves due to the formation of aggregates. When varying the degree of neutralization of the polyacid to values lower than 0.1 a different pattern of behavior is seen with respect to the composition of the complex, depending on which polymer has a higher degree of polymerization (PAA or PVP). On the basis of quantitative analysis of the conductimetric titration data, a relationship is proposed to evaluate the degree of complexation between both macromolecules. This parameter diminishes with increasing charge density in the PAA chain, falling to zero for values of degree of neutralization close to 0.1. (C) 1998 Elsevier Science Ltd. All rights reserved.