Vinyl Polymerization. CLXXII. Polymerization of Methyl Methacrylate Initiated by Nickel Peroxide

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Abstract
When nickel peroxide was used as an initiator of the polymerization of methyl methacrylate, it was found that the radical polymerization proceeded easier than styrene under similar conditions, and that the polymers obtained at low temperatures showed somewhat increased syndiotactic sequence as compared with ordinary radical polymers. From the NMR determinations of the polymers resulted by nickel peroxide at various temperatures, the Bovey-Tiers relationship, that is, that the probabilities of formation of isotactic, syndiotactic, and heterotactic triads of monomer unit among the polymer chain are controlled by a single parameter of the probability of isotactic addition of monomer in the propagation step was confirmed in this case. Similarly, the ratio ki/ks in rate constants for isotactic and syndiotactic additions in the polymerization by nickel peroxide in bulk was expressed by the following equation: In this equation, the difference in activation energy and entropy were somewhat larger than those reported for ordinary radical polymerization. These results might be understandable if the monomers adsorbed on the solid nickel peroxide were favored to enter to the syndiotactic propagation.