Muscle-Mimetic Highly Tough, Conductive, and Stretchable Poly(ionic liquid) Liquid Crystalline Ionogels with Ultrafast Self-Healing, Super Adhesive, and Remarkable Shape Memory Properties

Abstract

Here, we report a simple method for preparing muscle-mimetic highly tough, conductive, and stretchable liquid crystalline ionogels which contains only one poly­(ionic liquid) (PIL) in an ionic liquid via in situ free radical photohomopolymerization by using nitrogen gas instead of air atmosphere. Due to eliminating the inhibition caused by dissolved oxygen, the polymerization under nitrogen gas has much higher molecular weight, lower critical sol–gel concentration, and stronger mechanical properties. More importantly, benefiting from the unique loofah-like microstructures along with the strong internal ionic interactions, entanglements of long PIL chains and liquid crystalline domains, the ionogels show special optical anisotropic, superstretchability (>8000%), high fracture strength (up to 16.52 MPa), high toughness (up to 39.22 MJ/m3), and have ultrafast self-healing, ultrastrong adhesive, and excellent shape memory properties. Due to its excellent stretchability and good conductive-strain responsiveness, the as-prepared ionogel can be easily applied for high-performance flexible and wearable sensors for motion detecting. Therefore, this paper provides an effective route and developed method to generate highly stretchable conductive liquid crystalline ionogels/elastomers that can be used in widespread flexible and wearable electronics.

Fluorescent double network ionogels with fast self-healability and high resilience for reliable human motion detection

“…33 The unique properties of ILs endow ionogel-based flexible sensors with advantages of chemical and thermodynamic stabilities, nonflammability, nonvolatility and high ionic conductivity. 8,16,17,34,35 For example, Jiang et al prepared flexible ionogels as skin-like sensors using thermoplastic polyurethane and ionic liquids. The ionogel-based sensor exhibits excellent sensitivity and rapid response (96 ms) to stimuli and a wide operating temperature window (À40 to 100 1C).…”

An ultra-tough and ultra-sensitive ionogel pressure/temperature sensor enabled by hierarchical design of both materials and devices

“…However, IG 0.825 -AL 0.26% -Zn 18% is still irreplaceable because its ionic conductivity is higher than that of other types of tough materials. Compared with the representative piezoresistive ionogel pressure sensors reported in recent years, [39][40][41][42][49][50][51][52][53] the sensitivity of 33.8 kPa −1 for the bilayer ionogel lm belongs to the ultra-sensitive pressure sensor (Fig. S24 †).…”

“…2g), IG 0.825 -AL 0.26% -Zn 18% exhibited outstanding comprehensive properties, including strain, stress, fracture energy, toughness and Young's modulus. 17,25,26,[38][39][40][41][42][43][44] Notably, the fracture strength (21 MPa), Young's modulus (325 MPa) and toughness (102 MJ m −3 ) of IG 0.85 -AL 0.065% -Zn 15% are substantially higher than those of existing ionogels (Fig. 2h).…”

Highly Tough, Stretchable, and Recyclable Ionogels with Crosslink-Enhanced Emission Characteristics for Anti-Counterfeiting and Motion Detection

“…30−32 Meanwhile, the ionogels with common noncovalent interactions as crosslinkages show excellent recyclability but moderate mechanical strength and poor thermal/mechanical stability, which is due to their weak interaction and bond strength. 33,34 Therefore, it is a big challenge to combine the ionogels of both good mechanical properties and recyclability.…”

“…Commonly, the ionogels that are crosslinked with covalent bonds have strong mechanical properties and excellent thermal/mechanical stability, which is essential for flexible conductive electronics with repetitive actions in a wide temperature range. , However, the permanent covalently crosslinked networks prevent these ionogels from achieving recyclability and regeneration, which puts a huge burden on the environment and limits their further application and sustainable development. To solve this problem, dynamic covalent bonds are incorporated into ionogels as crosslinkages and lead to moderate recycling and strong mechanical properties but suffer from extreme conditions and multistep chemical reactions. − Meanwhile, the ionogels with common noncovalent interactions as crosslinkages show excellent recyclability but moderate mechanical strength and poor thermal/mechanical stability, which is due to their weak interaction and bond strength. , Therefore, it is a big challenge to combine the ionogels of both good mechanical properties and recyclability.…”