Nanopixels Of Any Color

Making nanomaterials that emit multiple colors of light in well-defined patterns isn’t easy. Fluorescent dyes laid out on a nanoscale object tend to be so close together that they transfer energy among themselves, giving off distorted hues. Still, researchers want to make precision nanoemitters for use in miniaturized displays and data storage devices. To that end, Ian Manners of the University of Bristol, in England; Mitchell A. Winnik of the University of Toronto; and coworkers have produced multicolor nanostructures from block copolymers (Nat. Commun. 2014, DOI: 10.1038/ncomms4372). When immersed in ethyl acetate solvent, one of the polymer blocks is crystalline, and the other block—containing a red, green, or blue dye—is fluid. As a result, these copolymers form so-called cylindrical micelles with 10-nm-wide solid cores and brushlike coronas. Because the dyes are located in the coronas, they don’t spend time close to one another, and energy transfer and color distortion are avoided, Manners says. The researchers can mix red, green, and blue copolymer strands in standard ratios to generate micelles of any color, including white. Once an assembly is complete, the team can create “pixels” of a new color by adding a different mix of strands to the cylinder’s reactive ends.