Redox- and pH-responsive polymer gels with reversible sol–gel transitions and self-healing properties

Abstract

Covalent dynamic gels based on reversible acylhydrazone and disulfide bonds were prepared by crosslinking of benzhydrazide-containing poly(triazole) (PTB) with a novel disulfide-containing dialdehyde (C2) in DMF at ambient temperature. The PTB was synthesized by the metal- and solvent-free click polymerization of diazide and dialkyne monomers followed by treatment with hydrazine hydrate. The as-fabricated polymer gels exhibited both redox and pH stimuli-responsive behaviours. Analysis of the composition-property relationships of these polymer gels, specifically considering the effects of catalysts, molar ratio of benzhydrazide to aldehyde groups (–NH₂/–CHO), and gelator concentrations on rheological properties, were performed. Additionally, the gel revealed interesting self-healing properties through acylhydrazone exchange and/or disulfide exchange reactions. Employing this dynamic character, it is possible to regenerate the used gel, and thus it has the potential to perform in a range of dynamic or bioresponsive applications.