Keeping Track of Conductive Polymers

Plastics that are capable of conducting electricity—electrically conducting polymers—were the accidental result of an experiment in the late 1970s. At the time, the discovery that certain plastics could actually change their traditional "insulating" properties to conductive ones offered a future bright with possibilities.

03/01/2002


Plastics that are capable of conducting electricity—electrically conducting polymers—were the accidental result of an experiment in the late 1970s. At the time, the discovery that certain plastics could actually change their traditional "insulating" properties to conductive ones offered a future bright with possibilities. But two decades later, conductive polymers have failed to produce many marketable products.

As of now, they remain mostly on the sidelines of industry, although they are still heralded by some as a technology that has the ability to revolutionize the manufacturing and performance of products from electromagnetic shielding and light-emitting displays (LEDs) to batteries and sensors. For example, a report issued last year by Technical Insights , a business unit of market research firm Frost & Sullivan of San Antonio, Texas, offers a look into the ways that conductive polymers are being considered for and utilized in new applications.

Properties of polymers

Conductive polymers are a synthesized substance that is created by "doping"—or lacing—plastics with chemicals that change the molecular structure and allow electricity to pass along the chain of molecules. This doping process—similar to the technique used in making semiconductors—has been used to create a number of different polymers, with names like polyanilene , polythiophene , polypyrrole and polyacetlene .

Conductive polymers can be useful in differing fashions, because of their two most unique properties: conductivity and electroactivity . When first developed, they were immediately attractive to manufacturers and product developers because of their supposed flexibility, light weight and material cost savings.

For example, one of the early fantasies about conductive polymers was that they would eventually be able to replace copper wiring in a wide variety of applications. As of yet, polymers such as polyanilene can only conduct a fraction of what copper can, while still costing a great deal more.

But according to the Frost & Sullivan report, conductive polymers in many instances are already changing from a theoretical innovation to an integral part of product development.

Currently, one of the most prevalent uses of these polymers is in LEDs . In this application, the plastics—which because of their electroactivity will emit light in reaction to an electric signal—can actually replace the silicon substrate traditionally found in instrument and appliance displays. In fact, polymer material has actually played a role in the development of flat-screen televisions.

One of the earliest developed uses of conductive polymers was for batteries . Plastic batteries have been around for well over a decade, and while they have not become ubiquitous, researchers and developers—such as at the Department of Energy—express promise that they may eventually replace metal batteries to some degree, which can be heavy and expensive and do not hold a charge very well.

Elecromagnetic shielding could be another important applications. Published materials report that integrating these conductive materials into the casing of electrical devices and computers can absorb electromagnetic radiation and lessen its impact on surrounding objects. Also, using conductive materials as an insulator could possibly prevent the buildup of static electricity—dangerous in hazardous environments and the computer industry.

Polymers also have a possible future in sensors . This is because this electroactive material has the ability to change its electrical properties when it comes in contact with high levels of certain gases, for example.

Promise remains

Electrically conductive polymers still show compelling promise for electrical manufacturing, even though there are doubts about it becoming a consistent and competitive part of the market in the near term. But as developers continue to refine the mechanical properties, chemical stability and conductivity of these polymers, their integration into specified components will continue.



Potential Conductive Polymer Applications

EMI Shielding

LEDs

Batteries

Sensors



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