NEWS OF THE WEEK
COMPANIES ADVANCE BIOBASED CHEMICALS CLEANTECH: Start-ups are poised
to harness cellulosic feedstocks
Cobalt Technologies has developed a bacterium that ferments a variety of biomass-derived sugars.
B
IOBASED CHEMICAL production is taking a
COBALT TECHNOLOGIES
step forward with the announcement of two new projects—both involving venture-capitalbacked start-ups—to make chemicals out of nonfood cellulosic biomass. Cobalt Technologies is joining with the process development firm American Process to build a demonstration-scale n-butyl alcohol plant in Alpena, Mich. Genomatica, meanwhile, has formed a partnership with the Italian plastics maker Mossi & Ghisolfi to make 1,4-butanediol in Italy. High-volume industrial chemicals including lactic acid, propanediol, and citric acid are already manufactured by fermenting sugars derived from sugarcane or corn, and several companies are pursuing a new generation of sugar-based chemicals such as isobutyl alcohol,
MENDING WITH LIGHT MATERIALS CHEMISTRY: Light prompts metallosupramolecular polymers to repair themselves
S
CRATCHES, CUTS, and cracks, although they
may seem small, can add up to big bucks when they’re in polymer coatings. Just ask anyone who’s found a scratch to their car’s paint job. Thanks to a family of metallosupramolecular polymers, spotrepairing damage to paints, coatings, and polymer thin films could one day be as simple as shining an ultraviolet light on them (Nature, DOI: 10.1038/nature09963). The self-healing material, which comes from a group led by Stuart J. Rowan of Case Western Reserve H3C CH3 N N University and N N Christoph Weder of the Univer)p( )q O N.......... Zn2+.......N O( sity of Fribourg, n in Switzerland, N N is based on short N N polymer chains H3C CH3 that terminate in a ligand that can m ...
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The self-healing metallosupramolecular polymers are made from repeating units of a small polymer with ligands that bind to metals.
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succinic acid, and acrylic acid. To date, though, development of chemicals from cellulosic feedstocks has lagged. Cobalt plans to jump-start the process by piggybacking on a cellulosic ethanol project that American Process has already begun. Using $22 million in grants from the Department of Energy and the State of Michigan, American Process intends to open an ethanol plant early next year that’s based on a hemicellulosic waste stream from a neighboring wood-paneling firm. The plant will switch to making n-butyl alcohol in mid-2012, the partners say, producing more than 3 million lb annually. Key to the process, says Cobalt Chief Financial Officer Steven Shevick, is a Clostridium bacterium that ferments five-carbon sugars more efficiently than do conventional yeast and Escherichia coli. Similarly, Genomatica is taking advantage of a cellulosic ethanol project that is already under way at Mossi & Ghisolfi’s Crescentino site. M&G expects to be producing 88 million lb per year of ethanol by the first half of 2012. Some of the biomass feedstock will be diverted to 1,4-butanediol production later that year. Both deals are evidence that attention among developers of cellulosic biomass is shifting from ethanol to higher-value industrial chemicals, notes Erik Hoover, an analyst with Cleantech Data. The deals demonstrate momentum, but Hoover still sees many unknowns. “The opportunity for cellulosic biomass is enormous—if a hundred ‘ifs’ are satisfied,” he says.—MICHAEL MCCOY
coordinate to a metal ion. “When we put in a metal ion—in this case either zinc or lanthanum—the components bind to the metal and essentially form a highmolecular-weight polymer,” Rowan explains. When light shines on the polymer, the metal-binding ligands absorb the light’s energy and convert it into heat, which, in turn, makes the metal ion break ties with the ligands. “What you’re doing is depolymerizing the system using this photothermal process,” Rowan says. The depolymerized material is liquid and can flow into and heal cracks or scratches. “When you remove the light, the ligands rebind to the metal, polymerizing again and reestablishing the mechanical strength of the material,” he adds. All of which takes place in under a minute. There are other light-activated self-healing materials, but they rely on embedded particles or agents, which can be exhausted, or they use irreversible chemical reactions for healing. “We’ve used a reversible reaction,” Rowan says, “so you can scratch and heal and scratch and heal.” The work “represents a major step forward in the nascent field of self-healing polymers,” comments Michael R. Kessler, a materials science and engineering professor at Iowa State University. “What makes this approach potentially so useful is that the light can be directed locally at the damaged region, so that bonds are only re-formed where the damage occurs, allowing the undamaged material to continue to carry load during the healing process.”—BETHANY HALFORD
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