Self-Healing Ionogel-Enabled Self-Healing and Wide-Temperature Flexible Zinc-Air Batteries with Ultra-Long Cycling Lives.

Hydrogel-based zinc-air batteries (ZABs) are promising flexible rechargeable batteries. However, the practical application of hydrogel-based ZABs is limited by their short service life, narrow operating temperature range, and repair difficulty. Herein, a self-healing ionogel is synthesized by the photopolymerization of acrylamide and poly(ethylene glycol) monomethyl ether acrylate in 1-ethyl-3-methylimidazolium dicyanamide with zinc acetate dihydrate and first used as an electrolyte to fabricate self-healing ZABs. The obtained self-healing ionogel has a wide operating temperature range, good environmental and electrochemical stability, high ionic conductivity, satisfactory mechanical strength, repeatable and efficient self-healing properties enabled by the reversibility of hydrogen bonding, and the ability to inhibit the production of dendrites and by-products. Notably, the self-healing ionogel has the highest ionic conductivity and toughness compared to other reported self-healing ionogels. The prepared self-healing ionogel is used to assemble self-healing flexible ZABs with a wide operating temperature range. These ZABs have ultra-long cycling lives and excellent stability under harsh conditions. After being damaged, the ZABs can repeatedly self-heal to recover their battery performance, providing a long-lasting and reliable power supply for wearable devices. This work opens new opportunities for the development of electrolytes for ZABs.

Self-Adhesive Self-Healing Thermochromic Ionogels for Smart Windows with Excellent Environmental and Mechanical Stability, Solar Modulation, and Antifogging Capabilities.

Current thermochromic materials used in smart windows still face challenges, such as poor mechanical and environmental stability, unsatisfactory solar modulation capacity, and low transparency. Herein, the first self-adhesive self-healing thermochromic ionogels with excellent mechanical and environmental stability, antifogging capability, transparency, and solar modulation capability by loading binary ionic liquids (ILs) into rational-designed self-healing poly(urethaneurea) with acylsemicarbazide (ASCZ) moieties that have reversible and multiple hydrogen bonds are reported and their feasibility as smart windows with reliability and long service life is demonstrated. The self-healing thermochromic ionogels can switch between transparent and opaque without leakage or shrinkage, by the constrained reversible phase separation of ILs within the ionogels. The ionogels have the highest transparency and solar modulation capability among reported thermochromic materials and such excellent solar modulation capability can be well maintained after undergoing 1000 transitions, stretches, and bends, and storage at -30 °C, 60 °C, 90% RH, and vacuum environment for 2 months. The formation of high-density hydrogen bonds among the ASCZ moieties contributes to the excellent mechanical strength of the ionogels and allows the thermochromic ionogels to spontaneously heal their damages and be fully recycled at room temperature without the loss of thermochromic capabilities.

Research on the Secondary Forgeability of High Volume Fraction Whisker Reinforced Aluminum Matrix Composites of Original Squeeze Casting.

The poor formability of high volume fraction whisker reinforced aluminum matrix composites of original squeeze casting is an important factor restricting its further development and application. Currently, there are no reports on the secondary forgeability of aluminum matrix composites of original squeeze casting, although some papers on its first forgeability are published. The secondary forgeability is very important for most metals. This study aims to investigate the secondary forgeability of aluminum matrix composites. In this study, the secondary upsetting experiments of 20 vol% SiCw + Al18B4O33w/2024Al composites, treated by the original squeeze casting and extrusion, were carried out. The first upsetting deformation is close to the forming limit, the secondary upsetting deformation under the same deformation conditions was carried out to investigate the secondary forgeability. The experimental results show that, unlike aluminum alloys, the 20 vol% SiCw + Al18B4O33w/2024Al composites at the original squeeze casting and extrusion states have no secondary forgeability due to the whisker rotating and breaking during the secondary upsetting. The high volume fraction whisker reinforced aluminum matrix composites of original squeeze casting cannot be formed by the multiple-forging method since the cavities and cracks caused by whisker fracture continue to expand during secondary processing, which leads to further extension of macroscopic cracks.

Polymeric Complex-Based Transparent and Healable Ionogels with High Mechanical Strength and Ionic Conductivity as Reliable Strain Sensors.

Transparent and healable ionogels with very high mechanical strength, ionic conductivity, and resilience were fabricated for use as strain sensors with satisfactory reliability. The ionogels were fabricated by casting an aqueous solution of poly(vinyl alcohol) (PVA)-poly(vinylpyrrolidone) (PVP) complexes and 1-ethyl-3-methylimidazolium dicyanamide ([EMIm][DCA]), followed by evaporation of water at room temperature. The use of [EMIm][DCA] endowed the resulting ionogels with ionic conductivity at room temperature as high as 19.7 mS cm-1. Owing to the synergy between the abundant number of hydrogen bonds between PVA and PVP and the crystallized PVA segments that served as nanofillers, the resulting ionogels had good mechanical properties with a tensile stress of 7.7 MPa, a strain of 821%, and good resilience. In addition, the resulting ionogels showed rapid and repeatable sensing signals over a wide strain range (0.1-400%). This enabled them to detect both vigorous muscle movements, such as walking and jumping, and subtle muscle movements, such as pulse. Moreover, owing to the reversibility of hydrogen bonds, physically damaged mechanical properties, conductivity, and sensing ability of the ionogels could be conveniently healed with the assistance of water.

Superhydrophobic Foams with Chemical- and Mechanical-Damage-Healing Abilities Enabled by Self-Healing Polymers.

The fabrication of superhydrophobic materials capable of spontaneously healing both chemical and mechanical damages at ambient conditions has been a great challenge but highly desired. In this study, we propose that a self-healing hydrophobic polymer can be used to induce self-healing in a superhydrophobic material. As a demonstration, stable and porous self-healing superhydrophobic foams are fabricated by casting a mixture of healable poly(dimethylsiloxane) (PDMS)-based polyurea, multiwalled carbon nanotubes (MCNTs), and table salt, followed by solvent evaporation and removal of the salt template. The PDMS-based polyurea is able to heal mechanical damage by reforming hydrogen bonds and can also reverse chemical damage through surface reorganization. Thus, the chemically and mechanically damaged foams can spontaneously restore their superhydrophobicity and structural integrity at ambient conditions. Moreover, because of the satisfactory photothermal conversion of MCNTs, the temperature of the self-healing superhydrophobic foams can rapidly reach 60 °C under sunlight, which greatly increases the healing speed and healing efficiency of the foam.

Durable, Highly Electrically Conductive Cotton Fabrics with Healable Superamphiphobicity.

Electrically conductive fabrics with liquid repellency and corrosive resistance are strongly desirable for wearable displays, biomedical sensors, and so forth. In the present work, highly electrically conductive and healable superamphiphobic cotton fabrics are fabricated by a solution-dipping method that involves (NH4)2PdCl4-catalyzed electroless deposition of Cu and the subsequent deposition of a mixture of fluorinated-decyl polyhedral oligomeric silsesquioxane (F-POSS) and 1 H,1 H,2 H,2 H-perfluorooctyltriethoxysilane (POTS) on cotton fabrics. Because of their superamphiphobicity, the resulting fabrics are self-cleaning and exhibit excellent resistance against corrosive acidic and basic solutions. The as-prepared fabrics have a sheet resistance of ∼0.33 Ω·sq-1 and show excellent electromagnetic interference shielding and electrothermal heating ability. Because of the preserved F-POSS and POTS molecules, the fabrics can conveniently and repeatedly restore the loss of superamphiphobicity by applying a low voltage of 1.0 V or heating the fabrics at 135 °C to facilitate the migration of the preserved F-POSS and POTS to the surface of cotton fabrics. The integration of healable superamphiphobicity into the Cu-coated fabrics generates multiple functional cotton fabrics with excellent conductivity, electromagnetic interference shielding, self-cleaning ability, and significantly enhanced durability.

Transparent Polymeric Films Capable of Healing Millimeter-Scale Cuts.

Transparent polymeric films have been successfully integrated with self-healing capabilities. However, these films can only heal damages in the scale of several to several tens of micrometers, thereby greatly limiting their practical applications. The present study reports the fabrication of transparent polymeric films capable of healing millimeter-scale cuts by incorporating hydrogen-bonding units into zwitterionic polymer films, which are cross-linked by electrostatic interactions. The intermolecular interactions in the resulting films are greatly reduced when the films absorb water as a result of the reversibility of hydrogen-bonding and electrostatic interactions, thereby promoting the flowability of the film materials. Thus, the transparent films can heal 7.9 mm wide cuts and recover their damaged transparency following exposure to water. Furthermore, owing to their strong binding affinity to water molecules, the healable transparent films can effectively clean up oil fouled on dry films following rinsing with water. The combination of hydrogen bonding and electrostatic interactions provides a new means of design for transparent films with enhanced healing capabilities and an extended service life.

Oil-Repellent Antifogging Films with Water-Enabled Functional and Structural Healing Ability.

Healable oil-repellent antifogging films are fabricated by layer-by-layer assembly of hyaluronic acid (HA) and branched poly(ethylenimine) (bPEI), followed by immersion in the aqueous solutions of perfluorooctanesulfonic acid potassium salt (PFOS). The loading of PFOS endows the HA/bPEI films with oil repellency while maintaining its original hydrophilicity. The resulting films have an excellent antifogging ability, and various organic liquids can easily slide down the slightly tilted films (<10°) without any residue. Through water-assisted migration of PFOS and polyelectrolytes, oil-repellent antifogging films are able to repetitively and autonomously recover their damaged oil repellency and transparency caused by plasma etching, cutting, or scratching, prolonging their life span. The as-developed healable oil-repellent antifogging films have potential application as antifingerprint coatings for touch screens, antigraffiti coatings for signs and shop windows, and antifogging coatings for lenses, mirrors, and windshields.