pH-Responsive Saloplastics Based on Weak Polyelectrolytes: From Molecular Processes to Material Scale Properties

• Published in: Macromolecules Vol. 51; no. 12; pp. 4424 - 4434
• Main Authors: Rydzek, Gaulthier, Pakdel, Amir, Witecka, Agnieszka, Awang Shri, Dayangku Noorfazidah, Gaudière, Fabien, Nicolosi, Valeria, Mokarian-Tabari, Parvaneh, Schaaf, Pierre, Boulmedais, Fouzia, Ariga, Katsuhiko
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26.06.2018
• Subjects: Chemical Sciences
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.8b00609

Compact polyelectrolyte complexes (COPECs), also named saloplastics, represent a new class of material with high fracture strain and self-healing properties. Here, COPECs based on poly­(methacrylic acid) (PMAA) and poly­(allylamine hydrochloride) (PAH) were prepared by centrifugation at pH 7. The influence of postassembly pH changes was monitored chemically by ATR-FTIR, ICP, DSC, and TGA, morphologically by SEM, and mechanically by strain to break measurements. Postassembly pH stimuli misbalanced the charge ratio in COPECs, impacting their concentration in counterions, cross-link density, and polymer chain mobility. At the material level, changes were observed in the porosity, composition, water content, and mechanical properties of COPECs. The cross-link density was a prominent factor governing the saloplastic’s composition and water content. However, the porosity and mechanical properties were driven by several factors including salt-induced plasticization and conformational changes of polyelectrolytes. This work illustrates how multiple-scale consequences arise from a single change in the environment of COPECs, providing insights for future design of stimuli-responsive materials.