Highly-controlled regiospecific free-radical copolymerization of 1,3-diene monomers with sulfur dioxide.

The free-radical copolymerization of alkyl-substituted 1,3-butadienes with sulfur dioxide using a redox initiating system in toluene at -78 °C produced poly(diene sulfone)s consisting of a highly alternating and 1,4-regiospecific repeating structure, irrespective of the position and number of alkyl substituents, and the highly regioselective propagation via a free radical reaction mechanism is well accounted for by DFT calculations using model reactions.