Researchers discovered new form of active matter formed by the dissolution of droplets of an ionic liquid, according to a study published on June 30, 2018.
This study was conducted by the researchers at the Tokyo Metropolitan University. This discovery was made when the researchers observed an interplay between the dissolution of ionic liquids and the fluctuation of boundary around the droplet. Active matter are materials, which utilize ambient energy to self-propel and has potential applications to drug delivery and nano-machine propulsion. Also, self-driven motion is one of the key features of these materials.
This study shows that dissolution takes a complex turn when another component is added. The research team were studying the mechanism by which an ionic liquid dissolves in a mixture of water and ethanol. A small droplet of ionic liquid was placed at the bottom of a mixture of ethanol and water by the researchers to conduct the study. As per the temperature and ratio of ethanol to water used, a boundary or interface was expected to be formed between the ionic liquid and the water-ethanol above it, and then, gradual mixing of two. However, they observed that holes emerged inside the IL droplet and the holes could propel themselves inside the droplet.
The conditions were such that the mixture is close to a critical point, where small variations in composition can have major consequences. In this case, they were enough to locally promote mixing of the IL into the water-ethanol mixture. The drastic effect led to certain changes in the surface tension, which made the surface slightly bumpy, formed holes, and generated large flows required to move them around.
This study is expected to lead to the discovery of a broad new class of synthetic active matter. As it can find applications in drug delivery and propulsion at the nanometer scale, this new phenomenon might be helpful for research into novel industrial uses as well as further accelerate academic interest in active phenomena.