Highly compressible and environmentally adaptive conductors with high-tortuosity interconnected cellular architecture

Abstract

Conductive hydrogels that are highly elastic, fatigue resistant and environmentally adaptive are promising materials in the fields of wearable electronics, bioelectronics and soft robotics. However, these materials are challenging to develop, especially for use in harsh environments including organic solvents and extreme temperatures. Here we report a simple method for the fabrication of highly compressible and fatigue-resistant conductive hydrogels with reinforced-concrete-type constituents and high-tortuosity interconnected cellular architecture through a self-assembly and two-stage in situ polymerization process. The obtained composites exhibit excellent mechanical compressibility with negligible residual strain at 50% strain for >104 cyclic loadings both in air and water. Due to the structure-favoured anisotropic response to tensile deformations coupled with elastic recovery, the hydrogel is endowed with sensing dimensions which allow the direction and velocity of movement on the sensor surface to be distinguished. In addition, by interpenetrating with an oleophilic polymer network, highly elastic and adaptive organohydrogels are developed with outstanding sensing performance in a wide variety of organic solvents and cryogenic temperatures. These materials may therefore be suitable for use in flexible and wearable devices in harsh environments.

Multiscale Interpenetrated/Interconnected Network Design Confers All‐Carbon Aerogels with Unprecedented Thermomechanical Properties for Thermal Insulation under Extreme Environments

“…The loading–unloading strain–stress curves ( σ – ε ) showed a typical behavior observed in a foam‐like structure ( Figure a; and Figure S12, Supporting Information). [ 25 ] All samples showed an early linear region reflecting cell wall bending with a compressive strain of about 10%. As the nanoparticle loading increased, strain hardening in the region of 10% < ε < 60% became more pronounced.…”

Hydrogels for Flexible Electronics

“…Hydrogels with strain-insensitive conductivity are suitable for application as electrode materials in flexible bioelectronics, where undesired deformation could lead to artifacts. In recent years, metal-based materials such as metallic nanomaterials and liquid metals have been widely used to fabricate CHs due to their excellent electrical conductivity, along with attractive optical, catalytic, and magnetic properties. ,, However, metallic nanoparticles tend to aggregate inside the polymeric matrix, weakening the mechanical properties and reducing the conductivity of hydrogels. To overcome this challenge, researchers have considered the use of in situ formed metallic nanoparticles, nanosized metallic wires/rods, and special metals like liquid metals as feasible strategies.…”

Nanocomposite Hydrogel Actuators with Ordered Structures: From Nanoscale Control to Macroscale Deformations

“…[110] Recently, our group proposed to construct a fatigue-resistance and highly environmentally adaptive hydrogel with hierarchical structures across multiple length scales by using a simple strategy combining directional-freezing-induced self-assembly and two-stage in situ polymerization. [111] Although freeze casting was an excellent structural engineering strategy, its application in soft actuators was still challenging. We believed that with the further study of directional freezing technique, it would be an efficient strategy for the preparation of nanocomposite hydrogel actuators with complex but finer structure.…”