Researchers from the University of Delaware and Washington University in St. Louis have figured out how to train synthetic polymer molecules to behave--to literally self-assemble --and form into long, multicompartment cylinders 1,000 times thinner than a human hair, with potential uses in radiology, signal communication and the delivery of therapeutic drugs in the human body.

The discovery, a fundamental new tool for nanotechnology, is reported in the Aug. 3 issue of the prestigious journal 'Science.'

Darrin Pochan, associate professor of materials science and engineering at the University of Delaware, and Karen Wooley, the James S. McDonnell Distinguished Professor of Arts & Sciences at Washington University in St. Louis, led the research effort, which also involved co-authors Honggang Cui, a recent doctoral graduate, and doctoral student Sheng Zhong at UD, and Zhiyun Chen, a doctoral advisee of Wooley's. The research was supported by a Nanoscale Interdisciplinary Research Team (NIRT) grant from the National Science Foundation.

The focus of the research was block copolymers, which are synthetic molecules that contain two or more chemically different segments bonded together. Block copolymers are used to make a variety of materials such as plastics, rubber soles for shoes, and more recently, portable memory sticks (flash drives) for computers.

A block copolymer is a long-chain molecule, a length of which, or block, that is chemically different than the other, Pochan said. In our case, we took one block that loves water, and another part that does not. So when you put them in solution, the water-hating blocks try to get away from the water, and that's how you get different shapes, called micelles, to form.

The system used by the scientists consisted of a tri-block copolymer composed of polyacrylic acid, polymethylacrylate, and polystyrene introduced into a solution of tetrahydrofuran and water, and o
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Contact: Tracey Bryant
tbryant@udel.edu
302-831-8185
University of Delaware
3-Aug-2007