Abstract
The anionic polymerization of methyl methacrylate in tetrahydrofuran initiated by sodium-benzophenone ketyl was studied in rigorously purified systems by means of optical absorption measurements as well as conventional polymerization techniques to elucidate the initiation process involved. It was concluded, on the basis of kinetic behavior of the ketyl anion in reacting with the monomer and the UV absorption of the product polymer, that the addition of the ketyl anion to the monomer forms a propagating carbanion and thus initiates the polymerization. The addition reaction shows an activation energy of 13 kcal/mol and a rate constant of 1.2×10−2M−1sec−1 at −10°C. It was also found that no termination reaction occurs, so that the propagating chains are long-lived, though the chain transfer reaction takes place very slowly. The chain transfer reaction is brought about by electron transfer from the propagating carbanion to the benzophenone present in excess in the reaction system to regenerate the initiator.
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Ogasawara, M., Yoshida, H. & Hayashi, K. Sodium-Benzophenone Eetyl as an Initiator of Anionic Polymerization of Methyl Methacrylate. Polym J 7, 86–95 (1975). https://doi.org/10.1295/polymj.7.86
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DOI: https://doi.org/10.1295/polymj.7.86