How strong are strong poly(sulfonic acids)? An example of the poly(2-acrylamido-2-methyl-1-propanesulfonic acid)

Despite the significant interest in poly(sulfonic acids) as proton conductors and acid catalysts, their dissociation behavior is poorly studied. The influence of the polyelectrolyte effect on the dissociation of the strong poly(acid) is frequently neglected. Moreover, the decrease in distance between the sulfonic groups is thought to enhance the acid strength or charge carrier concentration. Using simple and reliable methods (pH measurements and potentiometric titration), it is demonstrated that a strong poly(sulfonic acid) such as poly (2-acrylamido-2-methyl-1-propanesulfonic acid) displays a limited (predicted by the Manning-Oosawa theory) degree of dissociation in a salt-free solution and maximal degree of dissociation equivalent to the monomer analog in the presence of NaCl excess. (C) 2015 Elsevier Ltd. All rights reserved.