Analysis of the potentiometric titration curves of poly(acrylic acid), poly(methacrylic acid) and poly(ethacrylic acid) in terms of species population distributions

For atactic poly(methacrylic acid) (PMAA) and poly(ethacrylic acid) (PEA) the conformational transition from a compact coil to a random coil upon ionization in aqueous solution is revealed by an analysis of the potentiometric titration curves. The treatment, proposed by Strauss, is couched in terms of successive ionization constants of a suitably sized subunit of the polymer chain. Consideration of the bimodal population distribution indicates that the conformational transition in PEA is more pronounced than in PMAA. This is most likely the result of the more hydrophobic side‐chain in PEA. In agreement with previous work, no “two‐state” conformational transition is observed upon ionization of poly(acrylic acid) (PAA).