Researcher Laura Rossi and her group at TU Delft have found a new way to build synthetic materials from tiny glass particles, the so-called colloids. Together with their colleagues from Queen’s University and the University of Amsterdam, they showed that they can easily use the shape of these colloids to make interesting building blocks for new materials, regardless of the different properties of the colloidal particles. Rossi: “This is striking, because it opens up a whole new way to think about material design.” Their work has been published in scientific progress this Friday.
Colloids are small particles, a few nanometers to a few microns in size. They consist of a collection of molecules and can have different properties depending on the material they are made of. “Under certain conditions, colloids can behave like atoms and molecules, but their interactions are less strong,” explains Rossi. “That makes them promising building blocks for new materials, for example for interactive materials that can adapt their properties to their environment.”
New way of material design
If left alone, the cubic colloids from this study, which are made of glass, will self-assemble into simple structures such as distorted cubic and hexagonal lattices. But instead of going straight from the building block to the final structure, the researchers took small groups of colloids and combined them into larger building blocks. When they assembled these clusters of colloids, they arrived at a different final structure with different material properties than the self-assembled structure. “From a chemistry standpoint, we always focus on how to produce a certain type of colloid,” Rossi says. “In this research, we shifted our focus to: how can we use the colloids that are already available to make interesting building blocks?”
A step forward
According to Rossi and her collaborator Greg van Anders, one of the ultimate goals of their research community is to design complex colloidal structures on-demand. “What we found here is very important because for potential applications we need procedures that can be scaled up, something that is difficult to achieve with most currently available approaches.” “The basic ability to pre-build identical pieces of different building blocks and have them make the same structure, or to take the same building block and pre-assemble different pieces to make different structures, are in fact the basic ‘chess moves’ for engineering complex structures. ”, adds Van Anders.
Although Rossi studies the fundamentals rather than the application of material design, she can envision possible applications for this particular work: “We found that the density of the structure we prepared was much lower than the density of the structure you would obtain. by the starting building blocks, so you can think of strong but lightweight materials for transport.”
To form a team
After Rossi’s team built clusters of colloids in the lab, they relied on Greg van Anders’s team at Queen’s University to build the final structure from preassembled clusters using a computer simulation. “On projects like this, it’s great to work with others who can run simulations, not only to understand in depth what’s happening, but also to test the likelihood of a successful lab experiment,” explains Rossi. † “And in this case, we got very convincing results that we understood the design process well and that the resulting material can be useful.”
The next step is actually building the final structure, made from the groups of colloids in the lab. “After seeing these results, I am convinced that it is possible,” says Rossi. “It would be great to have a physical version of this material and hold it in my hand.”
Form and interaction decoupling for colloidal pre-assembly, DOI: 10.1126/sciadv.abm0548
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