A switchable-transparency eutectogel enabled by multiple dynamic interactions for smart display applications

Abstract

Eutectogels constitute a new class of soft materials, integrating the most desirable characteristics of traditional gels and offering broad versatility across numerous applications. However, the development of thermo-responsive eutectogels, particularly those capable of thermally switchable transparency, remains highly challenging. In this study, a smart thermo-responsive eutectogel (STE) is fabricated using an N-isopropylacrylamide/metal salt-based deep eutectic solvent. Leveraging multiple hydrogen-bonding and coordination interactions, the STE displays excellent mechanical properties, achieving a tensile strength of 2.7 MPa. Notably, the STE demonstrates an upper critical solution temperature, undergoing a reversible transition from an opaque to a transparent state during the heating–cooling cycle. This unique feature enables its integration into various smart display systems. In addition to inherent self-adhesiveness and water-detachable characteristics, the STE exhibits thermally enhanced adhesion upon heating, demonstrating tunable adhesive behavior. The eutectogel also functions as a reliable strain sensor capable of detecting human motions, such as finger movements, over a wide temperature range. Furthermore, the STE possesses remarkable thermally assisted self-healing capability, ensuring both safety and long-term usability. Consequently, this work establishes a key foundation for the development of thermo-responsive and multifunctional eutectogels for next-generation smart display and wearable technologies.