By Paul Rincon
BBC News science reporter
A British research team has made it into the record books by creating the smallest "test tubes" known to science.
Materials scientists from Oxford and Nottingham universities performed chemical reactions inside tiny tubes of carbon atoms known as nanotubes.
Essentially, these are sheets of graphite an atom thick that are folded back on themselves to form cylinders.
They were used to force molecules into long straight chains, reports the journal Chemical Communications.
David Britz, at Oxford, and Andrei Khlobystov, at Nottingham, were able to observe the results of these reactions with an electron microscope.
The work has made it into the Guinness Book of World Records. The nano-sized test tubes are so tiny that around 300 billion would fit on to a full stop.
The technique could help improve industrial processes employing reactions in which single molecules join together to form long chains called polymers.
In this study, the molecules being joined were buckminsterfullerene oxides. Under normal circumstances, these would connect up into a twisted polymer that has many branches, like a tree.
When the same reactions take place in the nanotubes, the oxides are forced into a straight line with no branches. This is because they are confined by the nanotube.
In other words, the molecules formed a much better quality polymer when the reaction took place inside the tubes.
"The idea is that you can make the same materials you made before but potentially much more easily, at a cheaper price and with fewer environmental controls," Mr Britz told the BBC News website.
So far, the researchers have only reacted buckminsterfullerene oxide inside the nanotubes.
But they envisage that important polymers such as polyethylene, whose molecular shape is straightforward to control, could potentially be synthesised inside nanotubes.
'Sky's the limit'
Catalysts currently used to make straight-chain (high quality) polyethylene are sensitive to air and water. This means the material has to be synthesised in vats with a carefully controlled environment. Nano-test tubes could possibly provide an alternative to this process.
But, said Andrei Khlobystov at Nottingham: "More studies are needed to understand how our method can be used for real, practical applications"
And Mr Britz added: "[Our technique] is generally a way to constrain what you're making - to remove a degree of freedom when you're carrying out a reaction."
The tiny test tubes have an inner diameter of about 1.2 nanometres (billionths of a metre) and they are about two micrometres (millionths of a metre) long.
They have a volume of two "zeptolitres". The zeptolitre is currently the second smallest defined unit of volume.
Researchers hope that the technique could also be used to synthesise entirely new types of materials.
"As far as new materials are concerned, the sky is the limit. With enough creativity you could come up with plenty of uses for one-dimensional cavities," said Mr Britz.