Methyl methacrylate with labelled initiators

The presence of two hydroxyl groups per molecule in poly-(methyl methacrylate) and in polystyrene, each polymerized in aqueous media using the hydrogen peroxide-ferrous ion initiation system, has been established " by chemical analysis and determination of the average molecular weight. Poly-(methyl methacrylate) polymerized by azo-bis-isobutyronitrile labeled with radioactive has been shown to... 

Bevington et aL have found with the use of 3c-labelled benzoyl peroxide that the polymerization of methyl methacrylate or styrene in the presence of stilbene resulted in a high proportion of the initiator fragment attached to the stilbene unit. Tlie stilbene was found to react readily with oxygen-centred benzoyloxy radical, but was very unreactive to carbon-centred radicals. The stilbene is not polymerized. 

Using multi-wavelength transmission spectroscopy together with labeled compounds additional quantitative information on the reaction can be readily obtained. For example, Figure 5 shows the analysis of end groups (initiation radicals) per molecule as a function of conversion, in a methyl-methacrylate polymerization reaction. The initiator used in this case is benzoyl peroxide, a strong chromophore in the ultraviolet portion of the spectrum. " ... 

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