Synthesis of an azo macromolecular initiator composed of polyamide 4 and its initiation activity for the radical polymerization of vinyl monomers

Polyamide 4 containing an azo group (azo‐PA4) was synthesized by the ring‐opening polymerization of 2‐pyrrolidone when 4,4′‐azobiscyanopentanoyl chloride was used as an initiator. It was possible to control the molecular weight (MW) of the azo‐PA4s through the concentration of the initiator to some extent, and the highest weight‐average MW obtained was 35 × 103. To assess the initiation activity of the azo‐PA4 for radical polymerization, styrene (St) was used as a vinyl monomer. The azo‐PA4 was found to initiate the radical polymerization of St to produce polymers. Analyses by FT‐IR spectroscopy, 1H‐NMR, and differential scanning calorimetry after the homopolymers [polyamide 4 (PA4) and polystyrene (PSt)] were removed by Soxhlet extraction showed that the remaining polymer was PA4‐block‐PSt. Azo‐PA4 was also found to have an initiation activity for other vinyl monomers (methyl methacrylate, vinyl acetate, etc.).