Conjugation of polydienes by oxidants other than iodine

We have previously demonstrated that “I2-doping” of 1,4-polydienes, such as 1,4-polyisoprene and 1,4-polybutadiene, produces conjugated sequences of unsaturated double bonds in the polymer backbone. This rationalized the discovery made in 1988 that the conductivity of cis-1,4-polyisoprene can be increased by about 10 orders of magnitude upon doping with iodine, since polymeric conductivity requires the presence of conjugated structures. In our further investigation on the conjugation of 1,4-polydienes, we found that conjugated sequences can also be generated by exposure of cis-1,4-polyisoprene to oxidants other than iodine (e.g., titanium tetrachloride, antimony pentachloride, etc.). The conjugated polymers thus prepared show conductivities of up to 10−4 Ω−1cm−1.