Block copolymers derived from azobiscyanopentanoic acid. VI. Synthesis of a polyethyleneglycol–polystyrene block copolymer

Polycondensations were carried out between azobiscyanopentanoly chloride (ACPC) and polyethyleneglycols (PEG) having average molecular weight of 600, 2000, 8400, and 21,500, resulting in the chain extended PEG of several times the original polymer chain length and containing scissile NN units of azobiscyanopentanoic acid (ACPA). The poly(polyethyleneglycol‐azobiscyanopentanoate), designated as {article}{empty}{document}-- (PEG-- )ₙ^*{document} were thermally decomposed in the presence of styrene (St) to obtain PEG–PSt block copolymers. The amount of St consumed was proportional to [NN]0.5 and [St]1.2, whereas the chain length of the PSt segment was proportional to [NN]−0.5 and [St]0.8.