Slipping silkworms a little graphene makes for stronger silk
Silkworms mostly survive on the sustenance provided by mulberry leaves, but there may soon be a new ingredient in the mix. Scientists in China have discovered that by feeding graphene and carbon nanotubes to the creatures, the silk they produced was much stronger and could take on the ability to conduct electricity, something that may find its way into stronger clothes with embedded electronics.
While worm silk is already an in-demand material due to its strength and soft velvety-touch, that hasn't stopped scientists exploring ways to make it stronger. This has included adding dyes, nanoparticles and conductive plastics to the silk after it is already spun, or feeding such things to the worms beforehand.
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Now, scientists at China's Tsinghua University appear to have discovered just the right recipe. The team sprayed treated water containing either 0.2 percent single-walled carbon nanotubes or graphene onto the surface of mulberry leaves. The worms then consumed the leaves and went about their silk-spinning as normal.
But under testing, the material produced by the doped worms proved to be 50 percent stronger than regular silk. Inspecting this super-silk, the team found it possessed a more orderly crystal structure than regular silk and exhibited remnants of the carbon and graphene additives in the fibers.
Regular silk has low conductivity, which makes it useful for winter clothing as it keeps warm air closer to the body. But the scientists say this characteristic can be altered with their new silk. They cooked it at 1,050 °C (1,922 °F), which carbonized the material and instilled it with conductive properties.
While the team imagines its silk one day being put to use in a range of applications including protective fabrics, medical implants and electronics that are integrated into clothes, there are a few questions it will be looking to answer first. Its next steps involve detailing how exactly the worms blend the nanotubes and graphene into the silks, and what percentage of the final product they make up, along with whether or not that process causes any harm to the animal.
The research was published in the journal Nanoletters.