Tough and Stretchable Phenolic-Reinforced Double Network Deep Eutectic Solvent gels for Multifunctional Sensors with Environmental Adaptability

摘要

Conductive gels are perfect for various sensor applications due to theirinherent stretchability, flexibility, and electrical conductivity. However, theirpoor environmental adaptability and low fracture toughness restrict theirpotential applications. In this study, resorcinol-formaldehyde resin (RF) isused for the first time as a rigid network compounded with a flexiblepolyacrylic acid (PAA) network to successfully prepare a double network (DN)deep eutectic solvent gel (RF/PAA DN gel). The gel has high stress strength(1.04 MPa), compressive strength (10.63 MPa), and toughness (1.07 MJ m~(?3)).The addition of RF significantly improves the mechanical properties and givesthe RF/PAA DN gel certain photothermal effects, swelling resistance, andflame retardancy, broadening the scope of use and application of the gel.Importantly, as a multifunctional sensor, it can combine deformation sensing,temperature sensing, optical sensing, humidity sensing, and underwatersensing into one, with a wide range of stimuli responses and excellentsensing properties. Excellent environmental suitability also allows its use in awide range of temperatures (?20?90 ℃), humidity (55?90 RH),underwater, and in fire conditions. The work provides new ideas for choosingrigid networks and a novel strategy for developing multifunctional sensorswith excellent performance in complex environments.