Construction of high-strength multifunctional flexible sensors based on hydrophobic aggregation phase separation induced by differences in aggregation rate

Conductive hydrogels hold significant promise for flexible sensing and interdisciplinary applications, but their limited mechanical performance restricts technological progress. A critical challenge lies in the inherent trade-off between mechanical robustness and hysteresis loss, necessitating a balanced optimization for practical use, particularly in wide-frequency vibration sensing. To address this, we propose a design strategy for ionic liquid hydrogels leveraging microphase separation via hydrophobic aggregation. By tailoring the copolymerization kinetics of hydrophilic acrylic and hydrophobic methacrylate monomers, we construct a multi-scale phase-separated network that enables special energy dissipation mechanism, achieving a tensile strength exceeding 4 MPa. The hydrophobic surface groups repel interfacial water while hydrophilic domains maintain adhesion, endowing the hydrogel with superior strain-sensing performance and underwater operability, which are the key attributes for wearable electronics and intelligent underwater systems. Notably, by adjusting hydrophobic content, we develop a low-energy dissipation variant with an exceptional stress relaxation time of 1.96 × 10 6 s (∼22 days), ideal for long-term industrial vibration monitoring. The material's special viscoelastic properties, attributed to the balance between the conformational change ability of the molecular chain and the distribution of the hydrophobic aggregation domain, coupled with stable sensing across wide frequencies and strains, underscores its potential for conventional and vibration sensing technologies. • Microphase-separated network enables high strength and tunable dissipation, offering ultralong stress relaxation. • Optimal hydrophobic/hydrophilic balance ensures superior underwater sensing and operability for wearables. • Wide-frequency stability with balanced energy storage/dissipation allows versatile vibration sensing.