A new graphene foam stays squishy at the coldest temperatures

The superelastic material could be useful in space

graphene-based foam

DEEP FREEZE  Normal materials become brittle in deep cryogenic conditions, but a new graphene-based foam (shown in this scanning electron microscopy image) stays as flexible as ever.

K. Zhao/Science Advances 2019

A new graphene-based foam is the first material to remain soft and squishy even at deep cryogenic temperatures.

Most materials become stiff and brittle in extreme cold. But the new foam stays superelastic even when it’s subjected to the temperature of liquid helium: –269.15° Celsius. A material that remains pliable at such low temperatures could be used to build devices for use in space, researchers report online April 12 in Science Advances.

Inside this foam, oxygen atoms connect micrometer-sized patches of the superthin 2-D material graphene to create a meshlike structure (SN: 8/13/11, p. 26). The resulting material is flexible in deep cryogenic conditions because, even at such low temperatures, sheets of graphene are easily bendable and resistant to tearing, and the carbon-oxygen bonds that link these sheets together remain strong.

Yongsheng Chen, a materials scientist at Nankai University in Tianjin, China, and colleagues compressed samples of the material repeatedly at different temperatures. At –269.15° C, the foam behaved just as it did at room temperature, bouncing back to almost full size even after being compressed to one-tenth its original thickness. The material kept this resilience even when heated to about 1000° C and flattened hundreds of times.

Chen’s team suspects that different superthin materials, like 2-D semiconductors (SN Online: 2/13/18) or 2-D inorganic compounds (SN Online: 9/21/18) may create foams that might boast other unique properties.

Previously the staff writer for physical sciences at Science News, Maria Temming is the assistant managing editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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