Paving the way for a new era in materials science, a supercomputing-enabled “virtual laboratory” at University College London (UCL) promises to revolutionize the industry convention of trial-and-error testing for novel high performance materials known as nanocomposities.
Now, UCL’s James Suter, Deren Groen and Peter Coveney have turned to Edinburgh’s ARCHER supercomputer as well as the Science and Technology Facilities Council’s BlueJoule and BlueWonder out of Daresbury Laboratory to pioneer a new method of nanoscale research and development that would cut out the time-consuming guesswork and give scientists a sounder understanding of just how these materials work.
“[Developing composite materials] typically involves grinding and mixing the ingredients and hoping for the best,” says Suter, a postdoctoral research assistant in UCL’s Centre for Computational Science. “Of course we test the properties of the resulting materials, but our understanding of how they are structured and why they have the properties they have, is quite limited.”
The material the team was interested in is a blend of clay and synthetic polymer called montmorillonite. But with processes smaller even than the wavelength of light, direct observation is not possible, so the team focused on using powerful simulations.
“Our study developed computer simulations that describe precisely how the layered particles and the polymer chains interact,” says co-author Dr. Derek Groen. “The challenge is getting enough precision without the computer simulation being unmanageable. Certain processes need a highly detailed simulation which describes everything on a quantum level – but if we simulated the entire sample at that level, we’d literally need several decades of supercomputer time.”
In the blend of clay and synthetic polymer, for example, the clay is formed in sheets stacked above and below rows of polymer chains. To study the interaction where the clay sheet meets the polymer, Suter and his team require quantum simulation, but other portions of the model alter the level of detail to go only as granular as the atom or even a molecule.
The multiscale approach saves a great deal of compute time, but as Suter notes, the use of approximations necessitates a careful checking of the simulation’s fidelity.
“A lot of our work involved comparing the different types of simulation and ensuring that they gave results that were consistent with each other,” he explains. “The quantum mechanical model starts from first principles and is derived from the most basic laws of physics, so we know it’s right. But there are quite a few assumptions involved in a molecular model, and we had to ensure those assumptions were correct.”
The simulation showed for the first time how polymers and clay particles interact to form more complex shapes. As arrays of polymer-entangled clay sheets transform into stacks, they take on unique properties related to their structure. The team’s findings are a promising contribution to the field of composite materials manufacturing.