Plastics can now conduct electricity

Posted by David Gomez

The discovery of a new technique will make it possible to create a whole new collection of plastics with metallic and/or superconducting properties.  

According to the University of New South Wales, plastics normally conduct electricity very poorly and they are used to insulate electric cables but, by placing a thin sheet of metal onto a plastic film and mixing it into the polymer surface with an ion beam, Australian researchers have displayed that the system can be used to make inexpensive, durable, flexible and conductive plastics.
    
Their research has been published in the academic journal ChemPhysChem. The research team was led by Professor Paul Meredith and Associate Professor Ben Powell both at the University of Queensland and Associate Professor Adam Micolich of the UNSW School of Physics. The recent discovery reports experiments by former UQ Ph.D. student, Dr. Andrew Stephenson.
    
Methods that use ion beams are used often in the microelectronics industry to customize the conductivity of semiconductors such as silicon. Various attempts to adapt this process to plastic films have been tried since the 1980s with only minimal success, until now.
    
"What the team has been able to do here is use an ion beam to tune the properties of a plastic film so that it conducts electricity like the metals used in the electrical wires themselves, and even to act as a superconductor and pass electric current without resistance if cooled to low enough temperature," says Professor Meredith.
    
To show a potential uses of this new material, the team made electrical resistance thermometers that meet industrial standards. Evaluated against an industry standard platinum resistance thermometer, it had similar, or in some cases even superior accuracy.
    
"This material is so interesting because we can take all the desirable aspects of polymers - such as mechanical flexibility, robustness and low cost - and into the mix add good electrical conductivity, something not normally associated with plastics," says Professor Micolich. "It opens new avenues to making plastic electronics."
    
Andrew Stephenson said that the most exciting element of the discovery is how accurately the film’s ability to conduct or resist the flow of electrical current can be tweaked. It has tremendous potential for useful applications.
    
"In fact, we can vary the electrical resistivity over 10 orders of magnitude – put simply, that means we have ten billion options to adjust the recipe when we're making the plastic film. In theory, we can make plastics that conduct no electricity at all or as well as metals do – and everything in between,” Dr. Stephenson says.
    
These unheard-of materials can be simply produced with equipment commonly used in the microelectronics industry and are much more tolerant of exposure to oxygen when compared to standard semiconducting polymers.
    
When all of these factors are combined, these improvements may give ion beam processed polymer films a promising future in the development of soft materials for plastic electronics applications. The researchers say that their discovery is a fusion between current and next generation technology.