To date, various stretchable conductors have been fabricated, but simultaneous realization of the transparency, high stretchability, electrical conductivity, self-healing capability, and sensing property through a simple, fast, cost-efficient approach is still challenging. Here, α-lipoic acid (LA), a naturally small biological molecule found in humans and animals, is used to fabricate transparent (>85%), electrical conductivity, highly stretchable (strain up to 1100%), and rehealable (mechanical healing efficiency of 86%, electrical healing efficiency of 96%) ionic conductor by solvent-free one-step polymerization. Furthermore, the ionic conductors with appealing sensitivity can be served as strain sensors to detect and distinguish various human activities. Notably, this ionic conductor can be fully recycled and reprocessed into new ionic conductors or adhesives by a direct heating process, which offers a promising prospect in great reduction of electronic wastes that have brought acute environmental pollution. In consideration of the extremely facile preparation process, biological available materials, satisfactory functionalities, and full recyclability, the emergence of LA-based ionic conductors is believed to open up a new avenue for developing sustainable and wearable electronic devices in the future.features. [1][2][3][4] These conductors provide huge opportunities for promising applications of artificial muscles, skin sensors, biological actuators, stretchable displays, electronic eye cameras, intelligent robot arms, and others. [5][6][7][8][9][10][11] It was well known that the conventional electronic conductors are normally prepared from waferbased materials, which possess several drawbacks including fragility, rigidity, and low conductivity under large-scale deformations. [12] They cannot satisfy the demands of high stretchability, flexibility, durability, and stability. To achieve these criteria, strain engineering and nanocomposites are the two most adoptable strategies to fabricate stretchable conductors. In the first strategy, nonstretchable inorganic materials, such as silicon and metals, are geometrically patterned into buckled, serpentine structures on elastomeric substrates that renders the conductors excellent sensitivity and larger workable range of strain. [10,13,14] Nonetheless, most resultant conductors still show narrow range of strain from 20% to 70%, [15] and presents out-of-plane patterns that is difficult to encapsulate. Meanwhile, this strategy usually involves expensive and very complicated techniques, which greatly limits the further development of these conductors. Integrating conductive fillers into polymer matrix to produce nanocomposites used as stretchable conductors is the second strategy. [16] So far, various nanomaterials, such as carbon nanotubes, [17][18][19][20] carbon black, [21] graphene-based materials, [22,23] metal nanowires, and nanoparticles, [24,25] have been used as conductive fillers because of their unique mechanical and electrical properties. Although the robu...

Novel liquid‐free ionic conductive elastomers are fabricated by the polymerization of acrylic acid (AA) in polymerizable deep eutectic solvent (PDES). Liquid metal (LM) nanodroplets are used to initiate and further cross‐link polyacrylic acid (PAA) chains into a liquid‐free polymeric network without any extra initiators and cross‐linkers. The resulting liquid‐free ionic conductive elastomers exhibit high transparency (94.1%), ultra‐stretchability (2600%), and autonomous self‐healing. Spin trapping electron paramagnetic resonance and dye fading experiments reveal the generation of free radicals. UV–visible spectrometry and viscosity tests demonstrate the cross‐linking effect of Ga3+. The gelation time is much shorter than that of the conventional ammonium persulfate thermal initiation process. Furthermore, this liquid‐free polymer material is intrinsically resistant to freezing and drying, enabling it to operate under harsh conditions. In consideration of transparency, self‐healing, ultra‐stretchability, moldability, and sensory features, the resulting elastomeric conductor may hold promise for industrial applications in wearable devices, force mapping, and flexible electroluminescent devices.

The rational design of high-performance, flexible, transparent, electrically conducting sensor attracts considerable attention. However, these designed devices predominantly utilize glass and plastic substrates, which are expensive and not environmentally friendly. Here, novel transparent and conductive woods (TCWs) were fabricated by using renewable wood substrates and low-cost conductive polymers. Polymerizable deep eutectic solvents (PDES), acrylic-acid (AA)/choline chloride (ChCl), were used as backfilling agents and in situ photopolymerized in the delignified wood, which endowed the materials with high transparency (transmittance of 90%), good stretchability (strain up to 80%), and high electrical conductivity (0.16 S m −1 ). The retained cellulose orientation and strong interactions between the cellulose-rich template and poly(PDES) endow TCWs with excellent mechanical properties. Moreover, TCWs exhibited excellent sensing behaviors to strain/touch, even at low strain. Therefore, these materials can be used to detect weak pressure such as human being's subtle bending-release activities. This work provides a new route to fabricate functional composite materials and devices which have promising potential for electronics applications in flexible displays, tactile skin sensors, and other fields.

Ionic conductors are normally prepared from water-based materials in the solid form and feature a combination of intrinsic transparency and stretchability. The sensitivity toward humidity inevitably leads to dehydration or deliquescence issues, which will limit the long-term use of ionic conductors. Here, a novel ionic conductor based on natural bacterial cellulose (BC) and polymerizable deep eutectic solvents (PDESs) is developed for addressing the abovementioned drawbacks. The superstrong three-dimensional nanofiber network and strong interfacial interaction endow the BC−PDES ionic conductor with significantly enhanced mechanical properties (tensile strength of 8 × 10 5 Pa and compressive strength of 6.68 × 10 6 Pa). Furthermore, compared to deliquescent PDESs, BC−PDES composites showed obvious mechanical stability, which maintain good mechanical properties even when exposed to high humidity for 120 days. These materials were demonstrated to possess multiple sensitivity to external stimulus, such as strain, pressure, bend, and temperature. Thus, they can easily serve as supersensitive sensors to recognize physical activity of humans such as limb movements, throat vibrations, and handwriting. Moreover, the BC−PDES ionic conductors can be used in flexible, patterned electroluminescent devices. This work provides an efficient strategy for making cellulose-based sustainable and functional ionic conductors which have broad application in artificial flexible electronics and other products.

Cellulose-derived monolithic hierarchically porous MnOx/N-doped carbon aerogels exhibited excellent catalytic activity for the upgrading of lignocellulose-derived aldehydes.