The use of stabilized radicals with monomers and lauroyl peroxide

Three nitroxides (viz TEMPO and its 4-hydroxy- and 4-oxo-derivatives) have been used at 60 °C as inhibitors of the homopolymerizations of methyl methacrylate and acrylonitrile with lauroyl peroxide as initiator and toluene, tetrahydrofuran or dimethylformamide as diluent; diphenylpicrylhydrazyl has also been used as an inhibitor. The dependencies of the inhibition period upon the initial value of [inhibitor]/[initiator] and on the nature of the reaction medium resemble those found when using benzoyl peroxide as initiator in similar systems. The polymers of methyl methacrylate formed after inhibition have quite low average molecular weights and, when using the nitroxides, the polydispersities are comparatively small. There is discussion of the significance of the findings.