Binding of tetradecylpyridinium bromide to poly(vinyl alcohol) with various degrees of acetylation

Abstract

Binding of tetradecylpyridinium bromide to poly(vinyl alcohol) (PVA) with various degrees of acetylation was measured by using an electrode responsive to the surfactant. The binding tendency increases with increase in acetyl group content. Binding isotherms are analyzed in terms of the Scatchard plot, which indicates a Langmuir type binding at lower surfactant concentration followed by a weak cooperative interaction. For the Langmuir type binding, binding saturation increases, while the binding constant remains nearly constant with increase in acetyl-group content. Raising the temperature causes increased binding saturation and a reduced binding constant. Further analysis shows that about three acetyl groups in PVA are aggregated to provide a hydrophobic binding site for a surfactant molecule in the Langmuir binding scheme.