Highly Stretchable and Reconfigurable Ionogels with Unprecedented Thermoplasticity and Ultrafast Self-Healability Enabled by Gradient-Responsive Networks

Abstract

Nonvolatile and durable ionogels are emerging and promising stretchable ionic conductors for wearable electronics. However, the construction of reconfigurable and recyclable ionogels with high mechanical robustness, high stretchability, and autonomous healability, while heavily demanded, is very challenging. Here, we present a gradient-responsive cross-linking strategy for preparing a highly stretchable and reconfigurable thermoplastic engineering ionogel (TPEI). The design of both microcrystalline and dense hydrogen bonds in TPEI contributed to the formation of a unique gradient-responsive network. When the TPEI was meltprocessed under heating, the microcrystalline network structure was destroyed to form entangled polymer chains, while the highdensity hydrogen-bonded network structure was only partially destroyed. The remaining hydrogen-bonded network allowed the TPEI to have a high viscosity for melt processing. When the TPEI was cooled upon melting injection, extrusion, and spinning, the hydrogen-bonded network was rapidly reconstructed in tens of seconds, allowing it to be reconfigured and reshaped, while the microcrystalline network was further reconstructed to improve its mechanical strength and elasticity during subsequent aging. As a result, the TPEI exhibited engineering-hydrogel-level mechanical robustness (>100 kPa), extremely high stretchability (>1000%), wide-temperature tolerance (−20 to 80 °C), and ultrafast self-healability in few seconds. Due to its mechanical adaptability, high ionic conductivity, and reconfigurability, the TPEI was demonstrated to readily work as a self-healable and recyclable stretchable conductor in a wearable skin-inspired sensor for monitoring sophisticated human motions.

Highly Stretchable, Fast Self-Healing, and Waterproof Fluorinated Copolymer Ionogels with Selectively Enriched Ionic Liquids for Human-Motion Detection

“…It is because the higher content of ILs resulted in lower crystallinity and entanglement of polymer chains in SFCIs. Furthermore, the SFCI-2 exhibited a high mechanical strength (∼251 kPa) and a high stretchability (>6000%) (Movie S2), which was a record-high stretchability among the reported ionic conductors in the literature. ,− …”

A Waterproof Ion‐Conducting Fluorinated Elastomer with 6000% Stretchability, Superior Ionic Conductivity, and Harsh Environment Tolerance

“…Figure 2e shows the master curves of the storage moduli ( G ′), loss moduli ( G ″), and loss factor (tan δ) of the ICFE‐1.5M at a reference of 25 °C using the time‐temperature superposition principle. [ 20 ] Notably, the G ′ values are greater than the G ″ values over the entire angular frequency range from 10 –6 to 10 4 rad s –1 , indicating that the ICFE‐1.5M exhibits a solid‐like elasticity behavior. [ 21 ] The apparent activation energy ( E a ) of ICFE‐1.5M calculated by the Arrhenius equation (Equation S1, Supporting Information) varies over a wide range of 110.6–177.0 kJ mol –1 , suggesting a wide distribution of the bi‐continuous phase structure with different strengths (Figure 2f).…”

Spatial Adjustment Strategy to Improve the Sensitivity of Ionogels for Flexible Sensors

“…Without any change in chemical composition and ratio of the ionogel compared to B-IG, the prepared sensor by B-IG-5 has the best sensitivity, whose GF is calculated as 1.9 at the strain of 100% (up to 1.6 times of B-IG), and it increased to 2.82 at the strain of 300%. Figure 4c shows the GF versus strain for stretchable ionogel sensors based on various polymer and IL, [36][37][38][39][40][41][42][43][44][45][46][47][48][49] the type of polymer and IL basically determine the level of sensitivity. The detailed information and properties of our ionogel in different strains are listed in Table S4 (Supporting Information).…”