Elastic and Thermoreversible Iongels by Supramolecular PVA/Phenol Interactions

Abstract

Iongels have attracted much attention over the years as ion-conducting soft materials for applications in several technologies including stimuli-responsive drug release and flexible (bio)electronics. Nowadays, iongels with additional functionalities such as electronic conductivity, self-healing, thermo-responsiveness or biocompatibility are actively being searched for high demanding applications. In this work, we present a simple and rapid synthetic pathway to prepare hyperelastic and thermoreversible iongels. These iongels were prepared by supramolecular crosslinking between polyphenols biomolecules with a hydroxyl-rich biocompatible polymer such as poly(vinyl alcohol) (PVA) in the presence of ionic liquids. Using this strategy, a variety of iongels were obtained by combining different plant-derived polyphenol compounds such as gallic acid, pyrogallol, and tannic acid with imidazolium-based ionic liquids, namely [C2mim][N(CN)2] and [C2mim][Br]. A suite of characterization tools was used to study the structural, morphological, mechanical, rheological and thermal properties of the supramolecular iongels. These iongels can withstand large deformations (40 % under compression) with full recovery, revealing reversible transitions from solid to liquid state between 87 to 125 °C. Finally, the polyphenol-based thermoreversible iongels shows appropriated properties for their potential application as printable electrolytes for bioelectronics.