Self-Healing and Stretchable Tetrameric PVA-CNF-PVP-IL Complex Ionogel with High-Performance Ionic Thermoelectric Properties

Abstract

Self-healing and stretchable thermoelectric (TE) materials are crucial for the advancement of self-powered flexible wearable devices. Despite recent progress in the field, there remains a gap in developing materials that effectively combine self-healing capabilities with superior thermoelectric performance. In this study, we present a novel self-healing, stretchable tetrameric complex ionogel, which integrates polyvinyl alcohol (PVA), cellulose nanofibers (CNF), and polyvinyl pyrrolidone (PVP) to form a dynamic network structure. The innovative approach involves establishing reversible hydrogen bonds within the ionogel and utilizing PVA crystalline segments as nanofillers. We further incorporate the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide salt (EMIM:DCA) into the network, resulting in PVA-CNF-PVP-IL thermoelectric ionogels. The prepared ionogels exhibit remarkable mechanical properties, achieving a tensile strength of 560 KPa and an elongation at break of 587.02%. They also demonstrate impressive thermoelectric characteristics, with an ionic Seebeck coefficient of 8.997 mV K-1 and a conductivity of 36.09 mS cm-1 at 80% relative humidity. Furthermore, the ionogels exhibit excellent elastic tensile and self-healing properties, even after multiple cut/heal and stretch/release cycles, due to abundant noncovalent interactions, including hydrogen bonding and ion-dipole interactions. Importantly, the ionogels hold potential for use in ionic thermoelectric capacitors (ITEC), advancing the development of high-performance, self-healing, and flexible TE devices tailored for wearable applications.