Carnegie Mellon Researchers Create "Invisibility Cloak" For Colloidal Particles

March 06, 2008

Contact: Chriss Swaney
Carnegie Mellon
(412) 268-5776

PITTSBURGH—Carnegie Mellon University's Michael Bockstaller and Krzysztof Matyjaszewski have created a version of Harry Potter's famed "invisibility cloak" for nanoparticles.

Through a collaborative effort, researchers from the departments of Materials Science and Engineering and Chemistry have developed a new design paradigm that makes particles invisible.

In a recent edition of Advanced Materials Magazine, the researchers demonstrate that controlling the structure of nanoparticles can "shrink" their visible size by a factor of thousands without affecting a particle's actual physical dimension.

"What we are doing is creating a novel technique to control the architecture of nanoparticles that will remedy many of the problems associated with the application of nanomaterials that are so essential to business sectors such as the aerospace and cosmetics industry," said Bockstaller, an assistant professor of materials science and engineering.

Colloidal particles are omnipresent as additives in current material technologies in order to enhance strength and wear resistance and other attributes. Light scattering that is associated with the presence of particles often results in an undesirable whitish, or milky, appearance of nanoparticles, which presents a tremendous challenge to current material technologies. Carnegie Mellon researchers have successfully created a way to prevent this problem by grafting polymers onto the particles' surface.

"Essentially, what we learned how to do was to control the density, composition and size of polymers attached to inorganic materials which in turn improves the optical transparency of polymer composites. In a sense, light can flow freely through the particle by putting 'grease' onto its surface," said Matyjaszewski, the J.C. Warner University Professor of Natural Sciences in the Department of Chemistry.

The new "particle invisibility cloak" will help create a vast array of new material technologies that combine unknown property combinations such as strength and durability with optical transparency.

About Carnegie Mellon: Carnegie Mellon is a private research university with a distinctive mix of programs in engineering, computer science, robotics, business, public policy, fine arts and the humanities. More than 10,000 undergraduate and graduate students receive an education characterized by its focus on creating and implementing solutions for real problems, interdisciplinary collaboration, and innovation. A small student-to-faculty ratio provides an opportunity for close interaction between students and professors. While technology is pervasive on its 144-acre Pittsburgh campus, Carnegie Mellon is also distinctive among leading research universities for the world-renowned programs in its College of Fine Arts. A global university, Carnegie Mellon has campuses in Silicon Valley, Calif., and Qatar, and programs in Asia, Australia and Europe. For more, see www.cmu.edu.