Cooperative lnteraction between Poly(methacrylic acid) and Polyethyleneimines with Different Chain Lengths

Abstract

Both potentials and viscosities of the system of poly(methacrylic acid) (PMAA) and polyethyleneimines (PI) with different chain lengths were measured in aqueous solutions. The cooperative interaction between both components was discussed on the basis of the relationship between the stability of the complexes and the chain length of PI.
It was found that the interaction between PMAA and PI became stronger by increasing the chain length of PI, since the slopes ofthe potentiometric titration curves (PMAA by PI) were loosened gradually with the chain length of PI. Furthermore, the viscosity behavior of the system containing excess PI was characterized by the chain length of PI, so that the stability of the complex was closely connected with the chain length of PI. The viscosity of the complex solution was decreased with time. This result means that the complex seems to be in non-equilibrium state and to be stabilized with time. In these systems, the chain length of PI, that is, the cooperative interaction of binding sites, influenced the stabilization of the complexes positively.