Solvation Behaviors of Poly(acrylic acid) in Mixed Solvents of 2-Butoxyethanol + Water

Poly(acrylic acid) (PAA) is a well known weak polyelectrolyte in water but little is known about the solvation behavior of PAA in the mixtures of alcohol + water. In this study, the solvation behavior of PAA in the mixed solvents composed of 2-butoxyethanol (2BE) + water were investigated by measurements of volumetric properties, electrical conductivity, resonance light scattering and dynamic light scattering. All the measured experimental properties showed extrema or abrupt changes at a 2BE mole fraction of about 0.017 in 2BE + water. This may be explained by the formation of aggregates of 2BE and water, which is a poor solvent for PAA and results in cononsolvency of PAA in the mixture of the two good solvents, 2BE and water. We found that the volumetric property is sensitive to the occurrence of the specific aggregate of 2BE and water and the interactions in the complex fluid mixtures.