“Schwarzite structures are very much the same,” he says. “The theory shows that at the atomic scale, these materials can be very strong. It turns out that making the geometry bigger with polymer gives us a material with a high load-bearing capacity.”
Schwarzites also displayed excellent deformation characteristics, he says. “The way a material breaks is important,” Tiwary says. “You don’t want things to break catastrophically; you want them to break slowly. These structures are beautiful because if you apply force to one side, they deform slowly, layer by layer.
“You can make a whole building out of this material, and if something falls on it, it’s going to collapse slowly, so what’s inside will be protected,” he says.
Because they can take a variety of forms, the Rice team limited its investigation to primitive and gyroid structures, which have periodic minimal surfaces as originally conceived by Schwarz. In tests, both transferred loads across the entire geometry of the structures no matter which side was compressed. That held true in the atom-level simulations as well as for the printed models.
That was unexpected, says Douglas Galvão, a professor at the University of Campinas who studies nanostructures through molecular dynamics simulations. He suggested the project when Tiwary visited the Brazil campus as a research fellow through the American Physical Society and Brazilian Physical Society.
“It is a little surprising that some atomic-scale features are preserved in the printed structures,” Galvão says. “We discussed that it would be nice if we could translate schwarzite atomic models into 3-D printed structures. After some tentatives, it worked quite well. This paper is a good example of an effective theory-experiment collaboration.”