Nanoscale ice formations resembling the double helices of DNA will form when water molecules are frozen inside carbon nanotubes, detailed computer simulations suggest.
Researchers at the University of Nebraska, US, used a supercomputer to run detailed mathematical models of the behaviour of water molecules. In their simulations, they inserted the molecules into carbon nanotubes under high pressure, before cooling them to -23°C.
The scientists were surprised to see the molecules organise themselves into "spiral staircase" arrangements similar to those of a DNA helix. "It was very unexpected," Xiao Cheng Zeng, the computational nanotechnology expert who led the research told New Scientist. "We had expected ice to form into tube structures that have been observed before inside carbon nanotubes."
The simulations involved modelling the behaviour of water molecules packed inside nanotubes measuring between 1.35 and 1.9 nanometres in diameter, under pressures of 10 to 40,000 atmospheres. The combination of such a confined environment and such extreme pressures distorted the hydrogen bonds within each water molecule in ways never seen before, Zeng says.
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