The Early History of Polyaniline II: Elucidation of Structure and Redox States

Polyaniline, one of the primary parent conducting polymers, is a quite old material with a history dating back to 1834. With the distinction of being the oldest known fully synthetic polymer and successfully commercialized as several popular cotton dyes in the 1860s, this material was originally known by the name of its black dye, aniline black. Of course, throughout this early history, the chemical identity and structure of these early polyaniline products were completely unknown, and it was not until the 1870s that initial attempts began to reveal various structural aspects. The current report will present a detailed historical account of the efforts to determine the structures of these early aniline oxidation products over the time period of ca. 1870-1915. In addition to the identity and structure of specific products, studies revealing the interconversion of one species to another via both redox and acid-based processes will also be discussed, with these collective efforts resulting in a comprehensive model of these materials that has remained essentially unchanged to this day.