Viscoelastic properties and self-healing behavior in a family of supramolecular ionic blends from silicone functional oligomers

Supramolecular solid-like polymer gels were obtained, through acid-base interactions, starting from highly viscous amino-terminated and carboxylic-terminated telechelic PDMS oligomers, with different molecular weights, ranging approximately from 900 to 27 000 g/mol. The obtained blends were studied and characterized in terms of viscoelastic behavior, tensile properties, and self-healing abilities, with the aim of gaining a better understanding of structure-property relationships in these supramolecular ionic blends. IR spectroscopy confirmed the formation of supramolecular ionic interactions thanks to the presence of ammonium carboxylate group absorbance. Thermal analysis showed the formation of a crystalline phase at room temperature in some of the supramolecular blends when the molecular weight was lower than 27 000 g/mol. An increase in crystallinity by decreasing the chain length and therefore their molecular weights was also observed. These supramolecular PDMS materials showed self-healing abilities with a value of healing efficiency ranging from 25% up to 52%. Samples tested with creep recovery analyses showed a viscoelastic behavior. Interpolation of the creep curves according to the four-parameter Voigt model provides a relationship between the viscoelastic behavior of these PDMS materials and their self-healing abilities. Our results show how the control of the thermal, viscoelastic, and mechanical properties of these materials allows the design of supramolecular blends based on acid-base interactions with improved self-healing properties.