G. Inzelt: Conducting Polymers

Abstract

Intrinsically conducting polymers have been around for quite a while. In 1834, Runge reported a black substance obtained by treating aniline with oxidizing compounds. Fritzsche provided a more detailed description of this material as an oxidation product of aniline in 1840. Electrooxidation of aniline was first performed by Letheby in 1862; some improvement of the description (the product was actually an oligomer) was provided 1876 by Goppelsroeder. In 1909, Willstatter and Dorogi provided for the first time the now well-known picture of an aniline chain with head-to-tail coupling (in the para-position of the benzene ring), confirmed 1910 by Green and Woodhead. The detailed properties of intrinsically conducting polymers have been obtained more recently, starting with a seminal report from the electrochemists point of view by Diaz and Logan in 1980. Recognition in terms of a Nobel Prize finally arrived in 2000. Thus it appears appropriate to review the state of our knowledge by an expert in this field supplementing numerous reviews published in books, journals and series. A proper definition of the subject is important. There is good reason to call the materials intrinsically conducting polymers and not just simply—as preferred by the book’s author—conducting polymers. Macromolecular substances with all kinds of conducting materials added to confer electric conductance to an initially insulating material have been around for quite some time, and they have been widely used. And there are even materials like (SN)x. The book title provides a somewhat misleading abbreviation— the book reviewed here deals almost exclusively with intrinsically conducting polymers (ICPs). Taking into account the authors presumed aim—to provide an update and description of the state-of-the-art—a specific literature review providing an update would have been a good idea in this rapidly growing subject. The number of ten thousand publications on the subject—as mentioned in the text— appears to be a low estimate and calls for a systematic approach. A classification of electrochemically active polymer follows in chapter 2—but already this title indicates that we are looking at something different from the book’s title: Redox polymers (not necessarily electronically conducting), intrinsically conducting polymers ICPs (apparently the true subject of the book), ICPs with additional redox functionalities and copolymers from both latter classes of materials. The number of reports and publications on any one polymer is no reliable indicator of its importance (something which is certainly difficult to measure at all), but it appears arbitrary when polymers like e.g. polyflavins (why the s?) or polymelatonin are deemed worthy of a mention whereas polyindole hardly appears as a footnote (on. p. 37) and is not even mentioned in the index; polyindoline is not mentioned at all. A quick search in the reviewer’s own databank yielded 48 reports on polyindole and 4 on polyindoline. In an introductory book aimed at the novice in the field such omissions would be harmless but in a book like the present one it leaves the reader puzzled. The compounds which made it into this chapter (even Nafion