Conjugated Polymers

Dear Colleagues,

The science and technology of conjugated polymers continues to be a vibrant and exciting research area nearly 30 years after the initial explosion of interest in these materials. In the late 1970s and early 1980s the (re-)discovery of conjugated polymers like polyacetylene, polyaniline and polypyrrole ignited an intense investigation of the properties of these inherently conducting materials. An initial surge of applications were also proposed that included plastic electronics, batteries, sensors and mechanical actuators. Now, nearly 30 years later we are seeing the commercialisation of some of these areas. Issues relating to stability and processing have been tackled to enable mass production of various products.

The science of conjugated polymers continues to be a rich area of interest for fundamental studies in physics and chemistry. We are now able to design and assemble conjugated polymers from the molecular level and through a better understanding of structure – property relationships we can build increasingly sophisticated structures. Many applications for conjugated polymers rely on their facile and reversible electrochemistry, where the polymer can be oxidised and reduced with simultaneous change in properties. The switchable properties is the basis of the application as transistors, sensors, re-chargeable batteries, solar cells, capacitors and even mechanical actuators. The molecular level processes occurring during switching are, however, quite complex and the understanding of charge transport within and between molecules as well as associated ion and solvent exchange with surrounding media are continually being developed. Through this better understanding, we are able to tune the molecular structures and assemble devices from the nano to the macro level for improved performance. Furthermore, we are able to develop devices to operate at smaller and smaller dimensions. Single molecule devices can be achieved with conjugated polymers and applications in nanotechnology and micro-electomechanical systems (MEMS) are well-suited to conjugated polymers.

Finally, the use of conjugated polymers as a link between the electronic world and the biological world is a very exciting new direction. Conjugated polymers have the potential to revolutionise bionics: to enable sensing of biological systems in situ but also to modify biological functions including directing new cell growth for the repair of organs. Conjugated polymers can match the mechanical properties of biological tissue and can be chemically tuned to be biocompatible and potentially biodegradable. While much work still needs to be done in this area, the opportunity for controllable interactions with living tissue through a bio-conjugated polymer is close at hand:

Even after 3 decades of work on conjugated polymers, new areas are emerging and the special joint issue of the journals International Journal of Molecular Sciences, and Materials is a great chance to showcase the recent developments in the science and technology of these fascinating materials.

Prof. Dr. Geoffrey M. Spinks
Guest Editor