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Rainbow Polymer

June 29, 2011

Color-shifting polymers could make money and other documents harder to copy.

Transcript

BOB HIRSHON (host):

Ink that’s hard to fake…I’m Bob Hirshon and this is Science Update.

In recent years, many countries have made their money more colorful, to make it harder to forge. Now, British scientists have invented a colorful, shimmering material that can’t be photocopied. As University of Sheffield physicist Andrew Parnell explains, ordinary inks made from pigments look the same from any angle.

ANDREW PARNELL (University of Sheffield):

But our material, when you change the angle of viewing, you would see this shift in the color, which is really obvious, and people have seen this in nature in peacock feathers and other such things.

HIRSHON:

That’s because its color comes from its layered molecular structure, which reflects light in complex ways. Parnell’s team found they could make any color in the rainbow just by combining two different polymers in different ratios. He says the material might someday be used in optical electronics as well as in anti-counterfeiting efforts. I’m Bob Hirshon, for AAAS, the science society.