Hydrophobic eutectogels with heterostructure for wearable sensing and undersea alarms

Abstract

Eutectogels have attracted much attention for use in artificial electronic skin and wearable sensors. Nevertheless, most eutectogels suffer from poor mechanical strength and toughness, as well as pronounced hygroscopicity. Herein, a strategy is proposed to fabricate heterostructure eutectogels exhibiting exceptional integrated properties. Concretely, a hydrophilic/hydrophobic heteronetwork eutectogel was formed by polymerization-induced micro-phase separation in a hydrophobic deep eutectic solvent. The hydrophilic poly(hydroxyethyl acrylate) (PHEA) phase forms a hard phase that shows significantly enhanced mechanical strength; the hydrophobic poly(2,2,2-trifluoroethyl acrylate) (PTFEA) and poly(lauryl methacrylate) (PLMA) phases serve as the soft phase, improving toughness and water resistance. Adjusting the phase ratio yields a transparent eutectogel with suitable tensile strength (0.26 MPa), stretchability (elongation at break of 1265%), excellent ionic conductivity and anti-swelling in seawater. This superior comprehensive performance resulted from the tunable phase-separated structure, and it enabled a flexible touch sensor for accurate real-time undersea communications and smart alarms, as well as the motion-mapped self-closing and self-rotating of a robotic arm. This work advances eutectogel design through structure–property engineering.