Fluorosulphonic acid, polymerization

Anodic polymerization of benzene in concentrated acids has been performed with the working electrode immersed in the interfacial layer between benzene and the acid. Methanesulfonic acid (McSObH), sulfuric acid (20%), fuming sulfuric acid, fluorosulphonic acid (FSO3H) or triflic acid (CF3SO3H) were mixed with benzene, and it was shown that the monomer was only oxidized with the electrode placed in the interfacial layer either at a rather low potential (1 V versus SCE) or at constant current [104]. 

Not many initiators belong to this class even though the halogenoacetic, fluorosulphonic, and other acids are included. A detailed analysis of their polymerization mechanism is obscured by complex formation with monomer and with solvent, by the occurrence of aggregates, and by anion reactions in acids with an unstable anion. In spite of its apparent simplicity, initiation by Bronsted acids has not yet been investigated in detail. The pseudo-cationic polymerization of styrene is an instructive example. 

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