Conducting and Semiconducting Polymers for Military Applications
Plastics are usually used as insulators, but some actually can conduct electricity, opening up a new field of manufacturing.
A polymer is a large molecular structure composed of many repeated and linked simple molecules. Because of the relatively large molecular mass, polymers exhibit unique physical properties, including toughness, elasticity, and a tendency to form glasses and semi-crystalline structures. Polymers appear naturally, but can also be synthetically produced. Natural polymers include amber, shellac, wool, silk, and rubber. Common synthetic polymers include nylon, vinyl, silicone, and synthetic rubber.
The discovery of conducting polymers in the late 1970s by Alan MacDiarmid, Alan Heeger, and Hideki Shirakawa was the result of their Office of Naval Research (ONR) basic research grant and launched the field of electronic polymers. It ultimately led to their 2000 Nobel Prize Award for the discovery and development of conducting and semiconducting polymers.
Polymers were traditionally known for their insulating properties, so the discovery of conducting polymers generated a great deal of interest, but progress was impeded because the new materials were unstable. Funding by ONR in the 1980s led to stable conducting polymers, which were first used as antistatic coatings and are now used in many electronic devices.
In the 1990s, the semiconducting properties of these materials were developed leading to organic light emitting diode displays, improved optical communications devices, and printable electronics.
New opportunities were identified and pursued by ONR, including the adaptation of polymer blends for use in the development of more efficient solar cells. Recent advances are now poised to usher in a new generation of low-cost, lightweight, and flexible photovoltaics for both military and civilian applications.
The steady and patient basic and applied research investments in polymer research led to a new class of electronic materials with both commercial and military applications, which could not have been envisioned during those initial days in the late 1970s.
The Ground Renewable Expeditionary Energy Network System (GREENS) is a modular, transportable system for renewable energy collection and storage. With the advent of semiconducting and conducting polymers, these still relatively heavy solar arrays in the future could be made of lightweight and flexible materials. In addition, the tents in the background could themselves be made of energy-collecting fabrics.
(U.S. Navy photo by John F. Williams)