Chemists create nanotube structures that can expand and contract without breaking dow

[ScienceRocks]

Chemists create nanotube structures that can expand and contract without breaking down

September 21, 2012 by Bob Yirka (Phys.org)—

A group of chemists from China, Japan and Korea have succeeded in creating nanotubes that can be made to expand and contract in response to warm or cold water. Led by Myongsoo Lee of Seoul University, the team, as they describe in their paper published in the journal Science, manipulated a series of molecules into forming hexagons, which when stacked resulted in the formation of a nanotube. Upon subjecting the nanotube to warm or cold water, the nanotube was made to expand or contract on demand.

To create the nanotubes, researchers bent six molecules which caused them to automatically assemble themselves into a hexagon. Several of the hexagons were then stacked, creating a nanotube which displayed properties of expanding and contracting in the presence of warm or cold water. The expanding and contracting occurs due to the central molecule being a hydrocarbon called pyridine, which has a nitrogen atom attached to it. That atom attracts water molecules, causing some degree of expansion until the water is heated to 60 °C. At that point, the water molecule attraction is disrupted causing contraction.

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