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News from the World of Science
By Hawa Irfan
"There is a Great Future Ahead in Plastics"
The revelation that polymers can conduct low levels of electricity was discovered by accident in the 70's.
Plastics are synthetic polymers commonly known for their pliability, lightness and ability to be used as an insulator rather than a conductor with no free electrons to carry the current of electricity.
It was the Japanese researcher Hideki Shirakawa who inadvertently ruined an experiment, which produced a semi-conducting plastic.
Scientists at the University of Texas reported success in mending damaged nerves by fitting the severed ends into an electrically conductive plastic sleeve packed with sugar.
The sugar apparently encourages the growth of blood vessels, which in turn stimulate nerve regeneration.
Over a period of a few weeks the electrical properties of the plastic dissolves appearing to have a beneficial effect on the nerves.
At Auburn University, Alabama, scientists have developed anti-microbial rubber for potential use in medical supplies, gloves, aprons, catheters, baby bottles, pacifiers and condoms.
The special rubber contains receptors that cause chlorine atoms to cling to it and kill germs on contact.
Just by dipping the rubber into chlorine antiseptic power is replenished.
As for Shirakawa, the Japanese scientist from the University of Tsukuba, Japan, his achievements were rewarded, but shared in the Nobel Prize in Chemistry 2000. His co-winners were Alan J. Heeger of the University of California, Santa Barbara, and Alan G. MacDiarmid of the University of Pennsylvania, Philadelphia.
For a polymer to be able to conduct an electric current it must consist alternately of single and double bonds between the carbon atoms.
"This is part of a quiet revolution being brought about by the ability to manipulate materials, atom by atom," says polymer chemist Christopher Ober of Cornell University.
It must be "doped" which means that electrons are removed (through oxidation) or introduced (through reduction).
These "holes" or extra electrons can move along the molecule becoming electrically conductive.
Research on conductive polymers is closely related to the rapid development in molecular electronics.
The drawback here is that electronic polymers are much more susceptible to defects, and aren't as conductive as silicon, especially in tasks such as high speed computing.
Products that are available now on the market are new generation laptops, cell phones etc with a high performance due to the new plastics.
The aim is to produce a generation of superdurable plastic transistors, lasers, light-emitting diodes and flat panel displays.
Conductive plastics are being developed industrially for anti-static substances for photographic film, shields for computer screens (against electromagnetic radiation) and for "smart windows" (that can exclude sunlight).
Recently, plastic producers launched a high-profile media campaign aimed at bolstering the image of the material.
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