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Termination of Chains in Vinyl Polymerization by Metal Salts


IN a recent communication, Bamford, Jenkins and Johnston1 have stated that ferric chloride dissolved in non-aqueous solvents is reduced by polymer radicals according to the equation: and that in certain circumstances the rate of formation of divalent iron can be identified with the rate of initiation of polymerization. Our purpose is to report very briefly some recent results obtained in these laboratories, some of which have already been published2, which (a) indicate that the oxidation and reduction of organic radicals by metallic salts is a general phenomenon which can take place in a variety of media, (b) confirm that the rate of the reaction depends on the polymeric radical, (c) show that the rate depends on the nature of the metal ion, (d) show that in a polymerization system in which the probability of chain transfer is low this reaction can be used for determining the number average degree of polymerization, and (e) demonstrate that reaction (1) is useful in studying post-irradiation effects.

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COLLINSON, E., DAINTON, F. Termination of Chains in Vinyl Polymerization by Metal Salts. Nature 177, 1224–1225 (1956).

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