Estimation of Polyelectrolyte Phase Volume Based on the Analysis of Acid Dissociation Equilibia of Polyacrylic Acid

Abstract:

The acid dissociation equilibria of typical linear weak acid polyelectrolytes, polyacrylic acid (PAA), were investigated by a potentiometric titration method. The electrostatic effects on the equilibria have been rationalized based on a Gibbs-Donnan concept. The apparent acid dissociation constant of PAA at completely neutralized condition determined by extrapolation are quite close to acid dissociation constant of their monomeric acid. The effective volume and the radius of polyelectrolyte phase of PAA have been calculated experimentally by the non-ideality term of ΔpK values with an iterative procedure. The radiuses increase with increasing at α 0.2 region. It is attributable to the repulsion between negatively charged carboxylate groups is weak at lowly dissociated state, whereas the repulsion is strong in highly dissociated state.

• Periodical: Advanced Materials Research (Volumes 512-515)
• Pages: 2300-2303
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.512-515.2300
• Online since: May 2012
• Authors: Yu Hong Chai, Jian Guo Liu, Ming Xin Wang
• Keywords: Dissociation Equilibia, Gibbs-Donnan Model, Polyacrylic Acid

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