Viscous Vortical Flows
This is a comprehensive account of the asymptotic theory of slender vortices with diffusion cores. Addressed to both graduate students and researchers it describes the mathematical model and its numerical analysis. The asymptotic analysis involves two len
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Classification of Electrochemically Active Polymers
Electrochemically active polymers can be classified into several categories based on the mode of charge propagation (note that insulating polymers are not considered here except for those with variable conductivity). The mode of charge propagation 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 electronically 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 segmental 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
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2 Classification of Electrochemically Active Polymers
2.1.1
Redox Polymers Where the Redox Group Is Incorporated into the Chain (Condensation Redox Polymers, Organic Redox Polymers)
2.1.1.1
Poly(Tetracyanoquinodimethane) (PTCNQ) [1–22]
Synthesis: 2,5-bis(2-hydroxyethoxy)-7,70 ,8,80 -tetracyanoquinodimethane+ adipoyl chloride [2, 11, 14]. Redox reaction: ½TCNQpolym þ e þ ½Kþ sol ! ½TCNQ Kþ polym ; (2.1) ðblueÞ
ðorangeÞ
þ
½TCNQ K polym þ e
þ ½Kþ sol ! ½TCNQ2 K2 þ polym :
(2.2)
ðcolorlessÞ
The subscripts “polym” and “sol” denote the polymer and solution phases, respectively. These reaction formulae indicate that the electron transfer taking place at the metal–polymer interface is accompanied by ionic charge transfer at the polymer– solution interface, in order to maintain the electroneutrality within the polymer phase. Counterions usually enter the polymer phase, as shown above. However, less frequently the electroneutrality is established by the movement of co-ions present in the polymer phase, e.g., in so-called self-doped polymers. Oxidation reactions are often accompanie
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