Electrolytically initiated vinyl polymerization

After a short outline of the historic development of electroinitiated vinyl polymerization and a description of the early work in this field a survey is given on the most important initiation systems. The difficulties and problems which arise, in addition to conventional initiation of vinyl polymerization, are analyzed. Among others, these comprise the spatial heterogeneity of active particle production, the necessity of dissolving the electrolyte in the polymerization system, which preferably also should be a solvent for the polymer formed, the susceptibility of the electrode process to impurities, the eventual termination of the growing chains by the products of the process taking place at the counter‐electrode, and the possibility of simultaneous initiation of anionic and free radical polymerization at the cathode and of cationic and free radical polymerization at the anode. Some examples show that in spite of these numerous difficulties precise kinetic measurements are possible in some free radical as well as in some ionic initiation systems. While the initiation of free radical polymerization processes suffers from disappointingly low current yields (≈10 −3 ), throughout which makes this initiation much inferior to any conventional one, there are some positive features inherent in the electroinitiation of ionic polymerization. Especially, it is the possibility to carry out cationic polymerization exclusively in presence and under control of such counterions which are known to have favorable polymerization characteristics (this is to lead to high rates and molecular weights), however, the corresponding anhydrous acids of which do not exist, by merely oxidizing the monomer in presence of salts of these counterions (e.g. AgSbF 6 ). Due to the non‐availability of the corresponding anhydrous acid HSbF 6 this cannot be accomplished in a direct manner by conventional techniques.