Conductive Polymer
Introduction
Conductive polymers or "synthetically produced electroactive polymers" are a category of polymers that conduct electricity. Unlike most insulating polymers, these polymers possess a conjugated backbone that allows the movement of electrons along the polymer chain. This unique property has led to their widespread application in various fields such as organic electronic devices, electrochemical sensors, and energy storage systems.
History
The history of conductive polymers dates back to the late 19th century when Henry Letheby first reported the synthesis of polyaniline. However, it was not until the 20th century that the conductive properties of these polymers were fully recognized. In 1977, Alan J. Heeger, Alan MacDiarmid, and Hideki Shirakawa discovered that polyacetylene could be oxidized to form a conductive polymer. This groundbreaking discovery earned them the Nobel Prize in Chemistry in 2000.
Structure and Properties
Conductive polymers are characterized by their unique polymer structure, which includes a conjugated system of alternating single and double bonds. This structure allows for the delocalization of pi electrons, enabling electrical conductivity. The degree of conjugation and the level of doping (the introduction of impurities to modify electrical properties) significantly influence the conductivity of these polymers.
Types of Conductive Polymers
There are several types of conductive polymers, each with unique properties and applications. These include Polyaniline, Polypyrrole, Polythiophene, and Polyacetylene. Polyaniline, for instance, is widely used in anticorrosion coatings due to its excellent environmental stability. Polypyrrole, on the other hand, is commonly used in electrochromic devices due to its high electrical conductivity and stability.
Synthesis
The synthesis of conductive polymers typically involves the polymerization of monomers containing conjugated double bonds. This can be achieved through various methods such as chemical vapor deposition, electrochemical synthesis, and oxidative polymerization. The choice of synthesis method depends on several factors, including the desired properties of the final product and the nature of the starting materials.
Applications
Conductive polymers have found extensive applications in various fields. In the field of electronics, they are used in the production of organic light-emitting diodes (OLEDs), solar cells, and field-effect transistors (FETs). In the energy sector, they are used in the manufacture of supercapacitors and fuel cells. They also find use in biosensors, drug delivery systems, and electrochromic devices.
Future Perspectives
The future of conductive polymers looks promising, with ongoing research aimed at improving their properties and expanding their applications. Areas of focus include enhancing their conductivity, environmental stability, and processability. Additionally, efforts are being made to develop new synthesis methods that are more efficient and environmentally friendly.