Bend me, shape me, any way you want me: Scientists curve nanoparticle sheets into complex forms Read more: Bend me, shape me, any way you want me: Scientists curve nanoparticle sheets into complex forms
By Carla Reiter
Scientists have been making nanoparticles for more than two decades in two-dimensional sheets, three-dimensional crystals and random clusters. But they have never been able to get a sheet of nanoparticles to curve or fold into a complex three-dimensional structure. Now researchers from the University of Chicago, the University of Missouri and the U.S. Department of Energy’s Argonne National Laboratory have found a simple way to do exactly that.
The findings open the way for scientists to design membranes with tunable electrical, magnetic and mechanical properties that could be used in electronics and may even have implications for understanding biological systems.Working at the Center for Nanoscale Materials (CNM) and the Advanced Photon Source (APS), two DOE Office of Science User Facilities located at Argonne, the team got membranes of gold nanoparticles coated with organic molecules to curl into tubes when hit with an electron beam. Equally importantly, they have discovered how and why it happens.The scientists coat gold nanoparticles of a few thousand atoms each with an oil-like organic molecule that holds the gold particles together. When floated on water the particles form a sheet; when the water evaporates, it leaves the sheet suspended over a hole. “It’s almost like a drumhead,” says Xiao-Min Lin, the staff scientist at the Center for Nanoscale Materials who led the project. “But it’s a very thin membrane made of a single layer of nanoparticles.” To their surprise, when the scientists put the membrane into the beam of a scanning electron microscope, it folded. It folded every time, and always in the same direction.“That got our curiosity up,” said Lin. “Why is it bending in one direction?”
