Classification of Electrochemically Active Polymers

Abstract

Electrochemically active polymers can be classified into several categories based on the mode of charge propagation (note that insulating polymers are not consid-ered here except for those with variable conductivity). The mode of charge propa-gation is linked to the chemical structure of the polymer. The two main categories are electron-conducting polymers and proton (ion)-conducting polymers. We will focus on electron-conducting polymers here. We can also distinguish between two main classes of electron-conducting polymers based on the mode of electron transport: redox polymers and electroni-cally conducting polymers. In this chapter, we provide examples of each type of electron-conducting polymers, listing some of the most typical and widely studied of these polymers, as well as several new and interesting representatives of this class of materials. Some sections are also devoted to combinations, such as electronically conducting polymers containing redox functionalities and copolymers. Composites, which has been developed extensively during the recent years, are discussed too. 2.1 Redox Polymers Redox polymers contain electrostatically and spatially localized redox sites which can be oxidized or reduced, and the electrons are transported by an electron exchange reaction (electron hopping) between neighboring redox sites if the seg-mental motions enable this. Redox polymers can be divided into several subclasses: • Polymers that contain covalently attached redox sites, either built into the chain, or as pendant groups; the redox centers are mostly organic or organometallic molecules • Ion exchange polymeric systems (polyelectrolytes) where the redox active ions (mostly complex compounds) are held by electrostatic binding G. Inzelt, Conducting Polymers, Monographs in Electrochemistry, DOI 10.1007/978-3-642-27621-7_2, # Springer-Verlag Berlin Heidelberg 2012 7 2.