Super Stiff Stuff

Last week I wrote about flexible transistors. Within a few years, we might be wearing wrap-around phones or other bendy devices that use the organic components from Plastic Logic, a Cambridge, UK company.

This week brings something almost the opposite: ultrastiff metamaterials.

 Lawrence Livermore National Laboratory (LLNL) research team members and co-authors Eric Duoss, Julie Jackson, Chris Spadaccini, Xiaoyu “Rayne” Zheng, and Todd Weisgraber (left to right) in the lab holding larger versions of the architected materials that are highlighted in their June 19 Science  article. (Courtesy Lawrence Livermore National Laboratory.)

Lawrence Livermore National Laboratory (LLNL) research team members and co-authors Eric Duoss, Julie Jackson, Chris Spadaccini, Xiaoyu “Rayne” Zheng, and Todd Weisgraber (left to right) in the lab holding larger versions of the architected materials that are highlighted in their June 19 Science article. (Courtesy Lawrence Livermore National Laboratory.)

Sure, the world has lots of very stiff materials, ranging from uncooked pasta to glass, wooden boards, and tempered steel.

But metamaterials are engineered to have properties that wouldn’t occur in nature. And these materials are designed to be not only very stiff, but also ultralight and ultrastrong.

Researchers report on engineering the materials in this week’s issue of Science. Engineers at Lawrence Livermore National Laboratory (LLNL) and the Massachusetts Institute of Technology (MIT) worked on the team.

“These lightweight materials can withstand a load of at least 160,000 times their own weight,” LLNL Engineer Xiaoyu “Rayne” Zheng notes in the press release announcing the development.

The materials get their strength not so much from their chemical make-up, but from their structure at the microscale. As LLNL Engineer Chris Spadaccini explains in the release, that means they’re “governed by their geometric layout.”

In this case, the materials are built to make tiny lattices—structures of crossed tubes. That building takes place one tiny layer at a time with a special 3-D printing process.

Basically, the printer builds lattices of polymers and coats them with metals or ceramics. Afterward, heat melts away the polymers, leaving hollow metal or ceramic tubes.

The 3-D lattice of tubes is still very strong because of its geometric design. But removing the polymer leaves it extremely light.

Lawrence Livermore National Laboratory (LLNL) Engineer Xiaoyu “Rayne” Zheng -- lead author of the Science article -- studies a macroscale version of the unit cell which constitutes the ultralight, ultrastiff material described in the article (Courtesy Lawrence Livermore National Laboratory.)

Lawrence Livermore National Laboratory (LLNL) Engineer Xiaoyu “Rayne” Zheng — lead author of the Science article — studies a macroscale version of the unit cell which constitutes the ultralight, ultrastiff material described in the article (Courtesy Lawrence Livermore National Laboratory.)

The press release notes that the new materials could be very useful for the transportation and aerospace industries. Indeed, one can easily envision energy-efficient cars that also provide good crash protection. Lightweight, more durable planes and spacecraft would be great too.

But I expect people will also find uses for the materials that engineers aren’t even thinking of yet. For years now, for example, people have talked about aerogel’s potential aerospace applications. Yet now the bendy “frozen smoke” is also used for things like fast-charging supercapacitors.

I haven’t yet seen aerogel used for stage props, however. That was something my daughter and her high school ExploraVision team thought up when the group was brainstorming about future technology for stage crew. An aerogel sofa might have looked really cool for the right surrealistic play too.

But who knows? Maybe the new metamaterials will find their way into all sorts of creative uses.

Thanks to engineering, there’s always something new and challenging in this material world.

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