Polyampholytes

Abstract

Abstract Six amphoteric copolymers of different composition of 2‐vinylpyridine and methacrylic acid were investigated. The specific viscosities of the copolymer solutions exhibit a pronounced minimum at the isoelectric point and the spectrometric titration of the pyridinium groups shows a pronounced jump in pH at the isoelectric degree of ionization. A theory of the polyampholyte behavior, based on the shape changes of the macromolecules and the field energy of the ionized groups, is developed and compares satisfactorily with the experimental results. The theory permits inter alia the evaluation of the intrinsic dissociation constants of the monomeric units and the determination of the isoelectric points from copolymer composition.