Verification of transfer‐suppressed cationic polymerization of vinyl monomers

A general approach to a transfer‐suppressed proceeding of cationic vinyl polymerization is put forward. The fundamental principle of the method consists in stabilization of the counter‐ion by interaction with acceptors. This results in an orbital controlled cation‐anion interaction and by this, suppression of side reactions, for example chain transfer due to lowering the ß‐hydrogen acidity of the growing cation and the specific monomer solvation of the propagation transition state. It is shown that picric acid, initiated polymerization of p‐methoxyatyrene and vinyl ethers, runs free of transfer in contrast to LEWIS‐acid initiated systems. Cationic polymerization, initiated by iodine based systems, are in the same category as demonstrated by molecular weight distributions, monomer addition experiments, thermokinetical data and UV‐spectroscopical measurements. The results are discussed in the framework of a general energetic scheme of propagation via cation‐anion orbital controlled interactions with propagating ion pairs.