Issue Date: March 2, 2015
Molecular Rebar Design Unravels Carbon Nanotubes
A decade ago, the sky seemed to be the limit for carbon nanotubes. Prices were dropping, new capacity was coming on-line, and companies were touting the nanomaterials for their thermal conductivity, mechanical strength, and energy storage ability.
Many firms imagined a future in which carbon nanotubes would be widely used to reinforce polymers, provide electromagnetic shielding for electronics, and augment the charge-holding capability of batteries. Some analysts were predicting that nanotube sales would exceed $1 billion annually by now.
But truth be told, sales in 2014 barely reached $50 million. At about $100 per kg, carbon nanotubes are still expensive, as well as difficult to work with.
Now, Molecular Rebar Design, an Austin, Texas-based start-up, says it has come up with a breakthrough modification to carbon nanotubes, making them easier to use and lowering overall costs in a product.
The Saudi Arabian chemical giant Saudi Basic Industries Corp. apparently agrees. In January, SABIC formed a joint venture with Molecular Rebar called Black Diamond Structures. It is betting that Molecular Rebar’s technology will propel demand for nanotubes in consumer electronics, energy storage, and construction applications.
“Theoretically, nanotubes are wonderful,” says Kurt Swogger, Molecular Rebar’s chief executive. But most nanotube production processes yield micrometer-sized balls of entangled nanotubes that are almost impossible to disperse as discrete tubes in rubber, plastics, or battery electrolytes, he says. As a result, nanotubes have only made limited market inroads.
Swogger, a chemical engineer who led R&D at Dow Chemical’s multi-billion-dollar performance plastics business before he retired in 2007, figured there had to be a way to make nanotubes easier to use. He started up Molecular Rebar in 2008 with Clive Bosnyak, another Dow scientist and polyolefin expert.
Swogger won’t say exactly how he and his enterprise, which now has 28 employees, succeeded in unentangling the troublesome tubes. Some firms have tried surfactants, but he says Molecular Rebar’s solution involves a multistep acid treatment and filtration process.
Unentangled, the firm’s nanotubes form a reinforcing network in plastics and rubber similar to the metal rebar used to reinforce concrete, Swogger explains. But “instead of working like a two-dimensional crisscrossing network of steel in concrete, unentangled nanotubes become part of a 3-D composite-reinforcing system,” he says.
Because the nanotubes can be so readily dispersed, fewer are needed to strengthen a polymer or hold an electrical charge. Overall, the cost of using the tubes is lower, Swogger claims.
In years past, companies aggressively scaled up nanotube production in anticipation of demand that never arrived, points out Ross Kozarsky, an analyst at the technology consulting firm Lux Research. Bayer, for instance, built up nanotube capacity in Germany only to exit the business last year because of disappointing sales.
Globally, nanotube makers can crank out about 3,000 metric tons of the stuff annually, Kozarsky says. The trouble is that 2014 demand stood at just 520 metric tons, he says. But he expects sales to take off if advances such as Molecular Rebar’s take hold.
Kozarsky considers Molecular Rebar “among a handful of promising nanotube start-ups” in part because it doesn’t make the tubes. Rather, it buys nanotubes and sells them in a dispersible concentrate.
Other firms are similarly developing technology to make use of existing nanotube capacity. They include Zyvex Technologies, which produces polymer-modified carbon nanotube additives for plastics and rubber, and NanoSperse, a maker of nanomaterial dispersions for composites.
Until now, Swogger says, he and partner Bosnyak financed Molecular Rebar themselves, though a few unnamed companies helped by buying options on the firm’s technology. But Molecular Rebar is at a point where it needs an outside investor, such as SABIC, to help exploit opportunities.
With Molecular Rebar’s technology, Swogger contends, nanotubes can finally live up to their potential and usher better materials to market. “We and our customers can make a lot of money with nanotubes,” he says.
- Chemical & Engineering News
- ISSN 0009-2347
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