Synthesis and structural characterization of a liquid polyisoprene bearing amidoxime end groups

Azo-bis(isobutyroamidoxime) was synthesized and used as functionalized initiator to prepare a liquid isoprene bearing amidoxime end groups via radical polymerization. The polymer was characterized by FT-IR, Gel Permeation Chromatography and NMR. In particular, the structure of the polymer was investigated using 1D and 2D NMR techniques. The distribution of the different isoprene units (1,4-trans, 1,4-cis, 1,2 and 3,4), as well as the structure of the amidoxime end-groups was determined. It was found that the structure of the end groups was governed by the steric hindrance of the initiator. Only 1,4 and 4,1 functionalized end units were evidenced, with a majority of 4,1 end units.