Adaptive Ionogel Paint from Room‐Temperature Autonomous Polymerization of α‐Thioctic Acid for Stretchable and Healable Electronics

Abstract

Development of a universal stretchable ionic conductor coating on insulating substrates, irrespective of surface chemistry and substrate shapes, is of immense interest for compliant and integrative large‐area electronics but has proved to be extremely challenging. Existing methods relying either on the concurrent deposition of polymerizing precursors or on divided formulation and painting processes both suffer from several limitations in terms of adhesion, dehydration, processability, and surface pre‐treatment. Here an ionogel paint that is readily prepared from the concentration‐induced autonomous ring‐opening polymerization of a natural small molecule—α‐thioctic acid (TA) at ambient conditions is reported. The presence of ionic liquid prevents polyTA from further depolymerization via forming COOH···OS hydrogen bonds, resulting in ultra‐stretchable ionogels with widely tunable mechanical and conductive properties, self‐healability, as well as tissue‐like strain adaptability. Moreover, owing to its universal adhesion and adjustable rheology, the ionogel paint can be directly coated on diverse substrates with arbitrary shapes (including porous materials, 3D printed frames, and elastic threads) to render them ionic conductivity. Applications of the ionogel‐coated substrates as skin‐like highly sensitive and durable large‐strain sensors are further demonstrated, suggesting the ionogel paint's great potential in the emerging soft and stretchable electronics.

A Transparent, Highly Stretchable, Solvent‐Resistant, Recyclable Multifunctional Ionogel with Underwater Self‐Healing and Adhesion for Reliable Strain Sensors

“…This phenomenon of energy dissipation is commonly observed in many gel systems with noncovalent interactions. [17,34,35] With an increase of tensile strain, the hysteresis area and hysteresis ratio of the loading-unloading cycles both increased (Figure S14, Supporting Information). These results indicated that more noncovalent bonds in the ionogel network were destroyed as the strain increased, which dissipated more energy and triggered more structural change.…”

Highly Stretchable, Elastic, Healable, and Ultra-Durable Polyvinyl Alcohol-Based Ionic Conductors Capable of Safe Disposal

“…Figure 3e shows the stretchability and durability of the recently reported hydrogel-, organohydrogel-and ionogel-based ionic conductors. [10][11][12][13][14][19][20][21][24][25][26][27][28][29][30][31]34,35,[49][50][51][52][53][54][55][56][57][58] Our VPVA 40% -IL ionic conductors are at record levels in terms of their stretchability and durability, demonstrating their considerable potential for use in flexible electronics and devices.…”

Dual‐Channel Flexible Strain Sensors Based on Mechanofluorescent and Conductive Hydrogel Laminates

“…[21] Meanwhile, there has also been a growing interest to explore soft polymeric hydrogels for flexible sensors. [22][23][24][25][26][27][28][29][30][31][32] Different from elastomers, polymeric hydrogels usually have a 3D crosslinked hydrophilic network that is highly swollen by water. [5,33] Thus they are endowed with many unique advantages, including intrinsic soft wet nature, good biocompatibility, and especially tissue-like mechanical properties, which have made polymeric hydrogels promising candidates for flexible sensors.…”