This article deals with oxidative polymerisation of aromatic monomers such as phenols, anilines, diphenyl disulphides, aromatic hydrocarbons, pyrroles, and thiophenes. The polymerisation method has some advantages: the reaction temperatures are moderate, and the by-products are only water under catalysis with oxygen or hydrogen peroxide. The reaction mechanisms of oxidative polymerisation generally involve radical reaction intermediates, so the following coupling is not often easy to control via catalysts. The polymerisation produces aromatic polymers, including poly(phenylene oxide)s (PPOs), polyphenols, polyanilines (PANs), poly(phenylene sulphide)s, polyphenylenes, polypyrroles (PPYs), and polythiophenes (PTHs). Oxidative polymerisation of 2,6-dimethylphenol by a conventional copper catalyst produces the corresponding PPO, and its alloy with polystyrene is widely used as an engineering plastic. Enzyme catalysts can polymerise various phenolic monomers to give polyphenols, and from 2- and/or 6-unsubstituted phenols, tyrosinase model catalysts can produce regioregular PPOs. The polymerisation of aniline with chemical oxidants under acidic conditions yields PAN with high electronic conductivity. PAN nanofibers intrinsically form in acidic aqueous solutions, and PAN composites with carbon nanotubes and graphenes are synthesised by in-situ polymerisation. PPY has a conductivity as high as PAN, but the formation of PPY nanostructures requires structure-inducing agents or systems. The regioregularity for 3-substituted PTHs is essential for their high mobility, and by oxidative polymerisation, regioregular 3-ary-substituted PTHs can be obtained. PTHs having 3,4-ethylenedioxy group are practically produced via oxidative polymerisation and used as a transparent electrode material.
