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.