Application potential of conducting polymers

Intrinsically conducting polymers (ICPs) represent a special class of weak materials with electronic and ionic conductivity. Chemical and physical properties are dependent on their redox state. These properties allow a wide application as functional coatings. At constant film conditions, ICPs can be used in the dry or wet state due to their electronic conductivity, due to their porous structure or due to their processibility in microstructuring processes. The production of conducting electrodes on electrolyte condensers and the through hole plating of printed circuit boards (PCBs) represent typical examples. In sensors and membranes, the pore structure is applied. The application of variable properties, however, is of much greater interest. It is based on the change of charge, electronic states, chemical composition and mechanical properties during the reversible redox process. In contrast to original expectations, small intercalation factors hinder the application in batteries or supercaps. For OLEDs, however, most problems seem to be solved. Application of switching hydrophilic/hydrophobic properties is proved for offset printing but not yet applied. Usually, the anodic doping is investigated. The correspondent cathodic doping opens additional applications. The application of ICPs in functional coatings requires special properties such as fast response (e.g. in ms), stability for 103 cycles for batteries and 106 switches for displays, and a constant potential of discharge for batteries. Moreover, the stability against corrosion, overoxidation and delamination has to be guaranteed. Chemical modification of the monomer allows wide variations of properties, but economic requirements limit the price of the monomer and, thereby, the thickness or quality of the coating. (C) 2004 Elsevier Ltd. All rights reserved.