A hydrophobic eutectogel with excellent underwater Self-adhesion, Self-healing, Transparency, Stretchability, ionic Conductivity, and fully recyclability

As an emerging soft material, eutectogels have attracted widespread interest for their excellent optical, mechanical, ion-conductive, self-adhesive, and self-healing properties. However, these properties of eutectogels are usually heavily affected by water molecules, leading to functionality failure in wet or underwater environments. Here, a novel hydrophobic eutectogel (HEG) is rapidly prepared with the help of photopolymerization by simultaneously introducing soft and hard acrylate monomers in a hydrophobic benzyltriethylammonium chloride/thymol deep eutectic solvent. Due to the abundant non-covalent and hydrophobic interactions within the polymer network, the synthesized HEG addresses the shortcomings of conventional eutectogels that are sensitive to water, while enabling good self-healing and self-adhesive properties both in air and underwater. Typical HEGs also exhibit high transparency, tunable mechanical properties, and ionic conductivities. The combination of these advantages makes HEG very suitable for the use of underwater adhesives and sensors with stable performance. In addition, it can be also used to prepare fully self-healing, recyclable and flexible electroluminescent devices. The design and applications based on HEGs show great promise for wearable sensors, self-healing flexible devices, and iontronics. © 2023 Elsevier B.V.