Amido-thioether polymers containing pendant carboxylato groups: thermodynamics of protonation and copper(II) complex formation in dilute aqueous solution

• Published in: Die Makromolekulare Chemie 1993-12, Vol.194 (12), p.3329-3339
• Main Authors: Casolaro, Mario, Ranucci, Elisabetta, Bignotti, Fabio, Ferruti, Paolo
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Solution and gel properties
• ISSN: 0025-116X; 0025-116X
• DOI: 10.1002/macp.1993.021941211

Calorimetric data are reported for the enthalpy of protonation of pendant carboxylato groups in new polymers 1a–d containing amido and thioether moieties in their main chain. These data, together with potentiometric and viscometric data, afford a complete thermodynamic description of the protonation process of the new polyacids, which are water‐soluble in a narrow range of α (degree of protonation) values. Comparison with the non‐macromolecular model 2 revealed that the thermodynamic features are attributable to polyelectrolyte effects. In contrast with model 2, all polymers studied form stable hydroxocomplex species with copper(II) ion. The hypothesized [Cu(OH)2L2]2− (where L is the monomeric unit of the polymer) stoichiometry fits the potentiometric data well when processed with the ‘SUPERFIT’ program. The trend of the corresponding stability constant (log β) values is to decrease with increasing pH over a wide range.