British scientists have developed the world’s first practical plastic magnet.
The breakthrough could lead to new advances in computing and medical applications.
In the past, magnets were always metal. Then in 2001 a team of United States chemists from the University of Nebraska-Lincoln showed it is possible to make a magnet out of plastic.
But their magnet, and similar ones that followed, suffered a major drawback. They only worked at ultra-low temperatures, making them totally unsuitable for use in everyday products.
The new plastic magnet, developed by the University of Durham’s organic electroactive materials group, is the first in the world to operate at room temperature.
In an elementary test, the scientists have used it to pick up iron filings from a laboratory bench.
The magnet is a polymer — a chain of molecules — made from two compounds, called PANi and TCNQ, that have unusual electrical properties.
Normally, magnetism is generated as a result of electron spins lining up. In the plastic, a similar effect is achieved by lining up charged particles called free radicals.
At first the plastic showed little sign of becoming magnetic.
After three months of failure the researchers were about to give up when they decided to test the polymer samples one last time.
To their surprise, they found that the plastic had developed magnetic properties, New Scientist magazine reported.
Although the effect is weak compared with conventional metal magnets, the researchers are confident it can be improved.
Naveed Zaidi, who heads the team, said: ”The reaction is not yet 100% efficient along the polymer and the strength of effect varies throughout the material. Once we increase this efficiency this overall strength will certainly increase.”
The magnetic plastic is mostly likely to be used for coating computer hard discs, which could lead to a new generation of high-capacity discs.
It could also have medical applications, such as transducers for ear implants.
The organic materials used to make the polymer are less likely to be rejected by the body than metals. — Sapa-DPA