Controlled degradation of polyisoprene and polybutadiene: AÂ comparative study of two methods

Low molar mass carbonyl telechelic cis,1-4 polyisoprene (CTPI) and aldehyde telechelic cis, 1-4 polybutadiene (ATPB) were easily prepared by the controlled degradation of high molar mass 1,4-cis polyisoprene (PI) and 1,4-cis polybutadiene (PB) in a molar mass range of 5000-80 000 g mol−1. Two methods are compared: the direct one using only the periodic acid (H5IO6) to randomly cleave the chain and a second one where the chain are first epoxidized before being cleaved by the periodic acid. In both cases, a control of the final chain length was observed with nevertheless a better control of the final chain length, dispersity and chain-ends using the 2-steps procedure. Importance of the washing step in order to avoid side reactions on the carbonyl chain-ends is also discussed.