A new study has uncovered a previously unseen phenomenon — that curved surfaces can dramatically alter the shape of crystals as they form.
Scientists have studied crystallization since the time of Galileo, so it’s easy to imagine there’s nothing new to learn about the process. Harvard researchers might beg to differ.
A new study has uncovered a previously unseen phenomenon — that curved surfaces can dramatically alter the shape of crystals as they form. The finding could have applications ranging from applying coatings to nanoparticles used in industry to aiding in drug delivery, and may even help shed light on how viruses assemble. The work, conducted by researchers at Harvard’s Materials Research Science and Engineering Center and funded by the National Science Foundation, is described in a recent paper in Science.
To investigate how curved surfaces affect crystallization, Vinothan Manoharan, the Gordon McKay Professor of Chemical Engineering and a professor of physics, worked with physics postdoc Guangnan Meng to develop a system in which nanoscale colloidal particles were injected into water droplets. As the particles — about 10,000 times larger than atoms or molecules — organized themselves into crystalline structures, researchers were able to observe the process in real time.
“If you have the particles on a flat surface, like a piece of glass, they form a regular lattice, and they’re compact, with no preferred direction for crystal growth,” Manoharan said. “On a curved surface, however, they form a very different pattern. It looks like strips — almost like ribbons — and they branch out from different points.”
Importantly, Manoharan said, researchers found that changing the curvature of the surface — by changing the radius of the water droplet — resulted in changes to the crystalized “ribbons.”