New nanotech discovery pushes packaging potential
the chemical characteristics of carbon nanotubes, which could have
implications for future packaging applications.
Somenath Mitra, professor of chemistry and environmental sciences and Zafar Iqbal, also a professor of chemistry and environmental sciences at the New Jersey Institute of Technology (NJIT), found that by heating them in a closed vessel microwave oven, the tubes can be chemically modified without damaging their essential structure.
"A carbon nanotube is just carbon," said Mitra. "The surprise for us is that it's difficult to make nanotubes react with anything. They are like diamonds - very, very inert. They don't react and they don't dissolve in water. But, if you can change their chemical characteristics as we have done using our method, we see them transform right before our eyes."
Once the tiny, microscopic tubes are chemically altered, they become soluble in common solvents like water and alcohol, and new kinds of films or coatings can be produced. The functionalised nanotubes become more useful than the pristine ones because the functionalised groups can be tailored for specific applications.
Nanotechnology involves the study and use of materials at an extremely small scale - at sizes of millionths of a millimetre - and exploit the fact that some materials have different properties at this ultra small scale from those at a larger scale. One nanometer is the same as one millionth of a millimetre.
Carbon nanotubes, which were only discovered in 1991, are molecular-scale nano materials made from carbon atoms connected single-file in a tube. The tubes are closed at either end by hemispherical structures and typically exhibit lengths ranging from tens of micrometers to a few millimetres.
It is hoped that the new technology could revolutionise food packaging in the future. The Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology (SINTEF) for example is currently using nanotechnology to create small particles in the film and improve the transportation of some gases through the plastic film to pump out dirty air such as carbon dioxide.
It is hoped that the concept could be used to block out harmful gases that shorten the shelf life of food. For their part, Mitra and Iqbal also believe that their discovery could lead to cheaper and more environmentally friendly production.
"We understand ourselves to be the first in the world to have discovered this method," said Mitra. "The beauty is that our method is green and clean. We use no toxic material and reduce the reaction times from hours--on occasion even days--to three minutes."
Iqbal noted that the method costs much less than others currently used. "Plus, the solubility of our carbon nanotubes are several times higher than any other researcher has yet reported in this short amount of time."
Solubility is the most essential characteristic of carbon nanotubes since researchers must be able to dissolve them to see how they work.
"Nanotubes are opening new vistas for products and design," said Mitra.
The pair, aided by doctoral student Yubing Wang, have written "Microwave-Induced, Green and Rapid Chemical Functionalisation of Single-Walled Carbon Nanotubes," to be published in a forthcoming issue of the journal Carbon.
