n e w s of t h e w e e k Still, the study highlights the importance of both gas-phase and coupled gasphase particle chemistry in developing air pollution controls, adds Atkinson. Methods used to achieve the ozone standards may not work to achieve the particulate standards, he says. "What may be optimum for ozone may not be optimum for particles." Elizabeth Wilson
bon particles. The nanotubes are metallic, semiconducting, or insulating depending on the preparation method. "Our method offers controlled growth of nanotubes that are free of carbon particles," Walton tells C&EN. "We etched tracks in the cobalt with a laser and our microscopy images show vigorous growth of the nanotubes at right angles from the edges of the laser tracks." According to Malcolm L. H. Green, inorganic chemistry professor at Oxford University, controlling the diameters and lengths of the nanotubes is a key problem. "What one is looking for now is a straightforward, reproducible way of An international team of scientists has making nanotubes with controlled dimenused a patterned catalyst to produce sions on a laboratory scale," he says. bundles of aligned carbon nanotubes in Scanning and transmission electron high yield that are free of contaminating microscopy reveal that the nanotube carbon particles. bundles prepared by the Sussex team are Chemistry professor Sir Harold W. Kro- uniform in length and external diameter to, reader in chemistry David R. M. and consist of between 60 and 80 Walton, and coworkers at the School of graphitic tubules. Chemistry, Physics & Environmental SciDaniel T. Colbert, faculty fellow in ence at the University of Sussex, England, the chemistry department at Rice University, Houston, comments that it is a fine piece of work. "It demonstrates the production of nicely aligned multiwalled nanotubes from a new carbon feedstock," he says. "But its novelty is diminished by its close relation to the method of production of multiwalled nanotubes by a commercial outfit in Boston, called Hyperion." The Hyperion method has been patented, Scanning electron microscope image of two bundles of note the authors of the aligned nanotubes. Nature paper. "Pyrolytic formation of nanoproduced the nanotubes by pyrolysis of a tubes in high yield that are substantially triazine using laser-etched thin films of a free from pyrolytic carbon overcoatings cobalt catalyst on a silica wafer [Nature, [has] been reported by Hyperion Inc., 388, 52 (1997)]. The research was carried but full details of the methods and prodout in collaboration with scientists at the uct characterization have not been Materials Research Laboratory, University published," according to the paper. of California, Santa Barbara, and the Walton points out that 2-amino-4,6-diInstitute of Physics, National Autonomous chloro-s-triazine, the precursor used by University of Mexico in Mexico City. the Sussex team to prepare the aligned Carbon nanotubes are hollow, nano- nanotubes, is "rather exotic." The team meter-scale diameter tubes of concentric plans further exploration of the route, graphitic carbon with potential applica- however. "We are trying to improve the tions in nanoscale engineering, electron- efficiency of production and scale it up," ics, and catalysis. Those produced by Walton says. "We intend to test a range commonly used methods, such as the of catalysts. Our aim, now that we have carbon-arc discharge method, have chaot- alignment, is to make the nanotubes ic arrangements, variable dimensions, longer and vary their diameters." and are contaminated by polyhedral carMichael Freemantle
Laser etching yields aligned nanotubes
8 JULY 7, 1997 C&EN
Hercules, Danaklon spin out fibers joint venture Hercules and Danaklon Group have combined their fibers businesses into an as-yet-unnamed joint venture. Danaklon is a unit of Jacob Holm & Sons, a Danish holding company. According to John Montgomery, who will be president and chief executive officer of the new venture, "The new company will be the world's largest producer of fine-denier polypropylene staple fiber dedicated to serving the hygiene, industrial, automotive, and decorative fabric markets." Montgomery was appointed vice president and general manager of Hercules' fibers business in February 1997. The Hercules business going into the joint venture makes polypropylene fiber used in nonwoven fabrics for diapers and other hygienic products. It also makes polypropylene fibers for upholstery fabrics for household furnishings and automotive interior trim. Danaklon manufactures and markets specialized polypropylene and bicomponent fibers for the hygiene market. The combined businesses had 1996 sales of $300 million. In its 1996 annual report, Hercules had listed Danaklon as one of its major competitors. The removal by Hercules of the fibers operations from its corporate portfolio marks the end of an era for the Wilmington, Del., company. Once a powerhouse in polypropylene and a significant player in fibers, the operations going into the joint venture are the last polypropylene and fibers units at the company, according to a spokeswoman. Hercules put its polypropylene resins business into a joint venture with Montedison in 1983, ultimately getting out of that business entirely. It sold its carpet fibers business to DuPont in 1989. Hercules will own 51% of the joint venture, which will be headquartered in Wilmington. The board of managers will be chaired by Poul Plougmann Laursen, CEO of Jacob Holm & Sons, and it will include four representatives chosen by Hercules and three by Jacob Holm & Sons. Vincent J. Corbo, Hercules president and chief operating officer, will be deputy chairman. Hercules has manufacturing plants in Oxford, Ga.; Canada; and Mexico. Danaklon's plants are in Athens, Ga.; Denmark; and China. William Storck
