AsianScientist (Oct. 22, 2018) – Scientists in Japan have designed a tough ion gel that can self-heal at ambient temperatures. They reported their findings in Advanced Materials.
Ion gels—gels filled with salts in liquid form, or ionic liquids—have attracted much attention due to their unique properties, such as a low tendency to evaporate at room temperature, high thermal stability and high ionic conductivity. However, to be useful in flexible electronic devices, the ion gels must be able to withstand repeated stretching and bending.
In this study, researchers led by Dr. Ryota Tamate of Yokohama National University have created an ion gel that can self-heal without any external stimuli at room temperature. The ion gel was created by combining two materials, or ‘blocks’ together, forming what is called a diblock copolymer.
The combination of the liquid salts and the diblock copolymer material resulted in a final structure that is responsible for the material’s desirable qualities. The block that is repelled by ionic liquids makes up the core, while the outside is composed of chains that interact with one another via multiple hydrogen bonds.
“Hydrogen bonding is reversible. This interaction contributes to our material’s ability to self-heal. In this study, by tuning the hydrogen bonding strength of polymer chains in ionic liquids, we utilized hydrogen bonding as a reversible cross-linking point of the ion gel. Furthermore, we proved that the micellar structure formed by the diblock copolymer material significantly improved the physical strength and self-standing ability of the ion gel,” said Tamate.
The researchers also reported that the self-healing process of their ion gel could be completed within a few hours. Furthermore, they found that the mechanical and electrochemical properties of a ‘healed’ gel were similar to those of an unaltered ion gel.
“For device applications, durability of the ion gel under various physically straining conditions should be quantitatively investigated. In addition, as the present diblock copolymer tends to absorb moisture from the air, we would like to seek other interactions between structures composed of several molecules that are stable in an open atmosphere for a long time. Different combinations of ionic liquids and their corresponding physical properties will be investigated,” said Tamate.
The article can be found at: Tamate et al. (2018) Self‐Healing Micellar Ion Gels Based on Multiple Hydrogen Bonding.
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Source: Yokohama National University; Photo: Shutterstock.
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