Nav: Home

Acetone experiences Leidenfrost effect, no hotplate needed

March 14, 2017

WASHINGTON, D.C., March 14, 2017 -- In doing his due diligence, cleaning his lab equipment, fluid physicist Stoffel Janssens from the Mathematical Soft Matter Unit in the Okinawa Institute of Science and Technology (OIST), Okinawa, Japan, took notice of the unusual interaction between the water and acetone droplets floating over the water surface as the droplets made their way to the drain.

"I noticed that sometimes, droplets briefly hover above the surface of a liquid before coalescing with the liquid," Janssens said. "Being intrigued by this phenomenon, I performed a literature study from which I concluded that a thin layer of gas between a droplet and a liquid surface can prevent coalescence."

In other words, what Janssens noticed was the acetone droplets were not mixing with the water because of their own form of the Leidenfrost effect, more commonly observed in water droplets on solid hot surfaces. In the case of water, the droplets float on a layer of steam formed where they meet the hot surface. Janssens and colleagues at OIST and the National Institute for Materials Science, both in Japan, studied the fluid dynamics of this interaction, and of the self-propulsion common to the Leidenfrost effect (which has its own name, Marangoni effect) to learn more about the underlying mechanics. Their surprising results appear this week in the journal Physics of Fluids, by AIP Publishing.

Normally, acetone (the main component in most nail polish removers) and water are miscible, meaning that, unlike oil and water, they intermix and do not separate or form droplets when mixed.

"Acetone has a boiling point of 56 C, well below that of water, and therefore evaporates strongly when it approaches a hot water surface," Janssens said. "I hypothesized that strong evaporation might create a gas layer between an acetone droplet and a water surface to suppress coalescence."

Janssens and his co-authors used high-speed videography to study the room-temperature droplet dynamics and their underlying mechanisms, looking closely at variables such as droplet size and velocity of self-propelled droplets. When they did, they found some unexpected behaviors.

"After analyzing movies obtained with high-speed camera imaging, I also noticed that a self-propelled droplet gradually becomes immersed beneath the undisturbed water surface," Janssens said. "This immersion starts when a droplet has a horizontal speed of about 14 cm/s. Finally, after carefully measuring the displacement of several droplets, we concluded that immersion causes drag."

They discovered the acetone droplets would propel themselves across the water's surface until reaching a velocity that would pull them under the surface, still in droplet form, where they then experience drag from the surrounding water.

"This type of drag by immersion is, to the best of our knowledge, not described in the literature and it is important to take into account when measuring drag on small objects supported by a liquid-gas interface," Janssens said. "Moreover, water walking creatures such as water striders, water spiders, and rove beetles might exploit drag by immersion for locomotion."

Stranger yet, they discovered that up to the point the droplet goes under the surface, the faster it moves, the faster it speeds up.

"We observed that a droplet accelerates faster with increasing horizontal speed up to the point that immersion occurs," Janssens said. "This initial runaway effect might be interesting for future research which involves self-propulsion driven by a Marangoni effect."

By comparing their data to theoretical models, Janssens and his colleagues developed a strategy for estimating the thickness of droplets' supportive vapor layer. However, there is still a lot more to understand about the unusual system and Janssens' team is still hard at work on this.

"Since there are many phenomena in this work which are poorly understood, there is a lot of work to be done," Janssens said. "I have controlled experiments designed to deepen our understanding of non-coalescence."
The article, "Behavior of self-propelled acetone droplets in a Leidenfrost state on liquid substrates," is authored by Stoffel D. Janssens, Satoshi Koizumi and Eliot Fried. The article will appear in Physics of Fluids March 14, 2017 (DOI: 10.1063/1.4977442). After that date, it can be accessed at


Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex or multiphase fluids. See

American Institute of Physics

Related Water Droplets Articles:

How tiny water droplets form can have a big impact on climate models
Droplets and bubbles are formed nearly everywhere, from boiling our morning coffee, to complex industrial processes and even volcanic eruptions.
Explained: Why water droplets 'bounce off the walls'
University of Warwick researchers can now explain why some water droplets bounce like a beach ball off surfaces, without ever actually touching them.
Active droplets
Using a mixture of oil droplets and hydrogel, medical active agents can be not only precisely dosed, but also continuously administered over periods of up to several days.
Autophagy degrades liquid droplets, but not aggregates, of proteins
Autophagy is a mechanism through which cellular protein is degraded.
Impact of water droplets on leaves quickly triggers stress responses in plants
An international study led by researchers at Lund University in Sweden and The University of Western Australia shows that the pressure from water droplets on a leaf surface triggers stress hormones like jasmonic acid.
Tiny droplets allow bacteria to survive daytime dryness on leaves
Microscopic droplets on the surface of leaves give refuge to bacteria that otherwise may not survive during the dry daytime, according to a new study published today in eLife.
New laws of attraction: Scientists print magnetic liquid droplets
Scientists at Berkeley Lab have made a new material that is both liquid and magnetic, opening the door to a new area of science in magnetic soft matter.
Cave droplets provide window into past climates
The chemistry of drip waters that form stalagmites and stalactites in caves around the world have given researchers an insight into our past climate.
A new way to make droplets bounce away
MIT researchers have found a way to minimize the contact between falling droplets and surfaces they land on, which could help to improve everything from preventing ice buildup on airplane wings to making waterproof fabrics more effective.
Using waves to move droplets
Self-cleaning surfaces and laboratories on a chip become even more efficient if we are able to control individual droplets.
More Water Droplets News and Water Droplets Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Processing The Pandemic
Between the pandemic and America's reckoning with racism and police brutality, many of us are anxious, angry, and depressed. This hour, TED Fellow and writer Laurel Braitman helps us process it all.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Invisible Allies
As scientists have been scrambling to find new and better ways to treat covid-19, they've come across some unexpected allies. Invisible and primordial, these protectors have been with us all along. And they just might help us to better weather this viral storm. To kick things off, we travel through time from a homeless shelter to a military hospital, pondering the pandemic-fighting power of the sun. And then, we dive deep into the periodic table to look at how a simple element might actually be a microbe's biggest foe. This episode was reported by Simon Adler and Molly Webster, and produced by Annie McEwen and Pat Walters. Support Radiolab today at