Self-assembly II: 3D nanostructures from 2D blueprints
Never-before-seen, three-dimensional nanoscale structures are coming out of a lab at the University of Wisconsin-Madison, thanks to an international research team's discovery that materials known as block copolymers will spontaneously assemble into intricate 3D shapes when deposited onto particular 2D surface patterns created with photolithography.
The structures the team has created are unique, composed of two tightly interwoven, yet completely independent, networks of channels and passages-all at the scale of atoms. "What we have are two interpenetrating meshes, both of which are completely continuous. And yet you could travel through one from end to end without ever entering the other," says Juan de Pablo, co-author of the team's report published in the Jan. 27 issue of Physical Review Letters.
The networks are also in perfect register with the photolithographic pattern underneath, which tells scientists exactly where each channel ends and gives them ready access to channel openings. The 2D to 3D leap is a powerful one because 2D photolithography is already a standard tool of the semiconductor industry used in the making of devices with dimensions substantially smaller than 100 nanometers.
"This research shows that lithography combined with block copolymers is more versatile and powerful than we thought. We can now create completely new structures that will no doubt have new properties and new applications," says de Pablo.
The team, consisting of de Pablo and colleagues at the University of Wisconsin-Madison Nanoscale Science and Engineering Center, Georg-August University in Germany and the Paul Scherrer Institute in Switzerland, see potential applications ranging from catalysis and chemical separation to semiconductor manufacturing.