The discovery centers on a new method for generating complex shapes from single components, the researchers from the University of Cambridge in England and Sofia University in Bulgaria have confirmed in a peer-reviewed article published in the science journal Nature.
In the lab, the scientists used a simple solution of oil and soapy water that was slowly frozen and made the discovery that ‘plastic crystal’ phases formed on the surface of the formulation play a role in shape-shifting into a variety of complex forms, including octahedrons and hexagons.
However, the difference in the method used by the scientists is that instead of focusing on the conventional top-down method to form these shapes, they created a simple but more efficient bottom-up approach to creating the shapes.
Determining the shape-forming process
The research team, led by Dr. Stoyan Smoukov wanted to determine what drives the shape-forming process and how to control it by building on previous knowledge about morphogenesis being driven by reaction-diffusion and the supposition that it is the physical properties of materials that control the process.
And this is what this latest research has focused on by studying the slowly-freezing oil droplets in the formulation, the scientists discovered that the droplets will shape-shift through a number of different forms, before reshaping to the original form once warmed back up again.
Importantly, the researchers discovered through this observation that the process is driven by the self-assembly of a plastic crystal phase that forms below the surface of the droplets.
"This plastic crystal phase seems to be what's causing the droplets to change shape, or break their symmetry," said Smoukov. "And in order to understand morphogenesis, it's vital that we understand what causes symmetry breaking."
Speed of freezing and size of droplets determine shape
But the vital discovery came when the scientists found out that by altering the size of the droplets in the formulation or the speed at which the freezing took place, they were able to control the sequence of shapes the droplets formed into, ultimately controlling the properties of the formulation.
"The plastic crystal phase has been of intense scientific interest recently, but no one so far has been able to harness it to exert forces or show this variety of shape-changes," said the paper's lead author Professor Nikolai Denkov of Sofia University, who first proposed the general explanation of the observed transformations.
"The phenomenon is so rich in combining several active areas of research that this study may open up new avenues for research in soft matter and materials science," said co-author Professor Slavka Tcholakova, also of Sofia University.