Plastic's Electrical Conductivity: A Misunderstood Material Trait

For a long time, it was thought that metals conduct electricity, and plastics don't. However, in 2000, Alan MacDiarmid, along with his Japanese colleague Hideki Shirakawa and US natural scientist Alan J. Heeger, was awarded the Nobel Prize in Chemistry for proving that plastics can conduct electricity under certain circumstances. The first plastic to make a name for itself as a conductor of electricity was polyacetylene, which was being manufactured by Shirakawa in the early 1970s.

Plastics can conduct electricity under certain circumstances

Polyacetylene was the first plastic to make a name for itself as a conductor of electricity. Its conductive properties were attributable to the addition of oxidants, which react with atmospheric oxygen, leading to a considerable reduction in conductivity levels.

At an atomic level, plastics are made up of long chains of carbon atoms, bonded with hydrogen, oxygen, or other elements. For a plastic to be a conductor of electricity, it must have a system of conjugated π electrons.

Nowadays, various highly stable conductive polymers are available on the market that have comparable electricity conductivity levels to copper.

Metals conduct electricity

Plastics are not good conductors of electricity, but they can conduct electricity under certain circumstances.

Metallic bonding is another reason why metals conduct electricity. Metal atoms are surrounded by a large, constantly moving body of electrons that are not linked to a specific atom. These delocalized electrons can move and repel one another in the direction of an electric current, conducting electricity throughout the metal.

Some metals are more commonly used as conductors than others due to being highly conductive. For example, copper is widely used for electrical wiring and equipment applications because it offers high conductivity coupled with affordability. Brass, which contains copper, is far less conductive because it is made up of additional materials that lower its conductivity, making it unsuitable for electrical purposes.

Plastics are insulators

Polyacetylene was the first plastic to be recognised as a conductor of electricity. Its conductive properties were attributed to the addition of oxidants, which react with atmospheric oxygen, leading to a considerable reduction in conductivity.

However, plastics are still considered insulators because they don't conduct electricity very well. They are used for insulating cables and shielding in electronics, blocking unintended electrical currents and protecting users from electric shock.

At an atomic level, plastics are made up of long chains of carbon atoms, bonded with hydrogen, oxygen, or other elements. For a plastic to conduct electricity, it must have a system of conjugated π electrons.

Plastics are made up of long chains of carbon atoms

Plastics are poor conductors of electricity, which is why they are used as insulators. However, they can conduct electricity under certain circumstances. The first condition for a plastic material to be a conductor of electricity is that it has a system of conjugated π electrons.

The ability of a material to conduct electricity is determined by the movement of electrons within it. In conductors, like metals, there are lots of free electrons, and this freedom of movement enables the flow of electric current. However, in insulators, like most plastics, the situation is quite different.

Polyacetylene was the first plastic to make a name for itself as a conductor of electricity. Its conductive properties were due to the addition of oxidants, which react with atmospheric oxygen, leading to a considerable reduction in conductivity. Nowadays, various highly stable conductive polymers are available on the market with comparable electricity conductivity levels to copper.

Polyacetylene is a plastic that conducts electricity

Plastics are generally considered to be poor conductors of electricity and are often used as insulators. However, in the 1970s, chemists Alan MacDiarmid, Alan Heeger, and Hideki Shirakawa discovered that plastics can conduct electricity under certain circumstances. This discovery earned them the Nobel Prize in Chemistry in 2000.

Polyacetylene, a plastic that is used for electrical insulation, was the first plastic to be recognised as a conductor of electricity. Its conductive properties are due to an alternating pattern of double and single bonds, which allows the sharing of electrons. This electron-sharing, or conjugation, enables the movement of electrons along the polymer chains, facilitating the conduction of electricity. However, polyacetylene did not initially conduct electricity well due to its high electron density. The addition of oxidants helped to reduce the electron density and improve conductivity.

Polyacetylene is a carbon-based, long-chain molecule, with each carbon atom bound to two neighbouring carbons and a single hydrogen atom. This structure is known as a conjugated π electron system, which is a requirement for plastic materials to conduct electricity. Polyacetylene has very high electrical conductivity in the doped stage, but it has limitations due to processing difficulties and instability in the presence of humidity and other gases.

Since the discovery of polyacetylene, scientists have developed other conductive polymers, such as PEDOT, which is used to prevent static shocks in electronics. These conductive polymers have comparable electricity conductivity levels to copper and are highly stable.

Frequently asked questions