Scientists at Yokohama National University and the University of Tokyo in Japan have designed an ion gel with excellent toughness and an ability to self-heal at ambient temperature without any external trigger or detectable change in the environment such as light or temperature. This new class of material has promising potential for building flexible electronic devices.
Ion gels have attracted much attention due to their unique properties such as low tendency to evaporate at room temperature, high thermal stability and a high ionic conductivity. The researchers demonstrated an ion gel that quickly heals on its own without any external stimuli at room temperature. They also demonstrate the material's excellent toughness resulting from multiple hydrogen bonds within the material.
"Wearable electronic devices are expected to be stretched and bent many times during daily use," said Ryota Tamate, a corresponding author and a JSPS postdoctoral researcher at the Graduate School of Engineering, Yokohama National University. "If the ion gel used in the wearable device has a self-healing property, it may fix cracks and damages during the repeated stretching and bending, and improve the device's durability."
The study, published in Advanced Materials in July of 2018, describes a specific type of polymer gel, called the ion gel, that is filled with salts in liquid form, or ionic liquids. This ion gel was created by combining two materials, or "blocks" -- one is repelled by ionic liquids while the other bonds with hydrogen. Together, they form what is called a diblock copolymer.
The combination of the liquid salts and the diblock copolymer material resulted in a final micellar structure that is responsible for all of 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.
The study is the first demonstration that the introduction of hydrogen bonding into ion gels can result in the material's strength as well as its ability to self-heal at room temperature.
"The self-healing process of this ion gel can be completed as quickly as within a few hours," Tamate said.
"Hydrogen bonding is reversible, and as a result, it is a promising interaction that contributes to a material's ability to self-heal due to their reversible nature. 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," he added.
While several types of tough ion gels have been reported so far, the authors write that achieving both self-healing ability as well as high toughness remains a great challenge. They also report that their gel's mechanical and electrochemical properties were similar to those of an otherwise unaltered or unchanged ion gel. The material's self-standing ability, the fact that it can self-heal at room temperature as well as easily processed in solution all make it a promising solid electrolyte for future applications in the area of flexible electronics - in particular to create self-healing electronics.
According to Tamate, "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. In addition, as physical properties of ionic liquids can be widely tuned by selection of cations and anions, the combination with different ionic liquids will be investigated."
Ultimately, the authors would like to develop new functional ion gels that can be used to create new devices that are flexible and thus wearable.
Yokohama National University (YNU or Yokokoku) is a Japanese national university founded in 1949. YNU provides students with a practical education utilizing the wide expertise of its faculty and facilitates engagement with the global community. YNU's strength in the academic research of practical application sciences leads to high-impact publications and contributes to international scientific research and the global society. For more information, please see: http://www.
Akiko Tsumura | EurekAlert!
Understanding high efficiency of deep ultraviolet LEDs
22.02.2019 | Tohoku University
Large-scale window material developed for PM2.5 capture and light tuning
18.02.2019 | University of Science and Technology of China
An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has combined radio telescopes from five continents to prove the existence of a narrow stream of material, a so-called jet, emerging from the only gravitational wave event involving two neutron stars observed so far. With its high sensitivity and excellent performance, the 100-m radio telescope in Effelsberg played an important role in the observations.
In August 2017, two neutron stars were observed colliding, producing gravitational waves that were detected by the American LIGO and European Virgo detectors....
Up to now, OLEDs have been used exclusively as a novel lighting technology for use in luminaires and lamps. However, flexible organic technology can offer much more: as an active lighting surface, it can be combined with a wide variety of materials, not just to modify but to revolutionize the functionality and design of countless existing products. To exemplify this, the Fraunhofer FEP together with the company EMDE development of light GmbH will be presenting hybrid flexible OLEDs integrated into textile designs within the EU-funded project PI-SCALE for the first time at LOPEC (March 19-21, 2019 in Munich, Germany) as examples of some of the many possible applications.
The Fraunhofer FEP, a provider of research and development services in the field of organic electronics, has long been involved in the development of...
For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.
The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...
Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens
Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...
Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light
When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...
11.02.2019 | Event News
30.01.2019 | Event News
16.01.2019 | Event News
22.02.2019 | Physics and Astronomy
22.02.2019 | Materials Sciences
22.02.2019 | Life Sciences