Interaction of water-soluble acrylic polymers with alcohols in aqueous solutions

The interactions of anionic acrylic polymers with a series of alcohols were investigated by means of surface tension, viscosity and solubility. Ethanol, n-propanol, n-butanol and acetylenic diol were used to probe two styrene-acrylic copolymers with differing acid values and hydrophobicity. Both polymers were dissolved in ammonium water at pH 8.5. The alcohol activity was found to decrease in the presence of these polymers. Both higher alcohol and polymer hydrophobicity led to more alcohol activity decrease. These phenomena were mainly attributed to the association between the polymer and alcohol via the hydrophobic driving force. Solubility increases of n-butanol and acetylenic diol in aqueous solutions in the presence of the polymers further support the notion of the polymer/alcohol association. The polymer–alcohol complex resulting from the association of the hydrophobic segments of the polymer and alcohol could become more hydrophilic and therefore more extended in aqueous solutions. This is indicated by the significant viscosity increase of the polymer solutions in the presence of as low as 0.1–0.5% of butanol or acetylenic diol. The binding isotherms of the alcohol on the polymer chains were also investigated. The results of surface tension and binding isotherm suggest an onset association of alcohol aggregates on the polymer chains.