PolyMMA radical

Generally there is fair agreement between selectivity in the reactions of a polymer radical with monomers and that in the corresponding reactions of the appropriate model radical. This feature can be well illustrated by considering the case of STY and MMA with the radicals Me CHPH and Me2C(COOMe) as expected from studies of copolymerizations, MMA is about twice as reactive as STY towards the radical regarded as a model for the poly STY radical whereas it is about half as reactive towards the radical representing a polyMMA radical [5]. 

Fig. 16a and b. Temperature dependence of intensity distribution of polyMMA radical (a) in anisole at —120 °C (b) in benzonitrile at indicated temperatures... 

C]BPO has been used in extensive studies of the participation in radical polymerizations of unsaturated substances not usually regarded as comonomers. Much of the work has involved stilbene and similar substances that show unexpectedly high reactivities towards the benzoyloxy radical. These additives become incorporated in polyMMA, for example, mainly at sites very close to the end-groups the resulting structures may be useful in subsequent attempts to modify the polymers. 

Fig. 6. ESR spectrum of radical trapped in polyMMA in polymerization of MMA at room temperature ...

The spectrum (b) in Fig. 49 is for the growing radical of polyMMA. Bresler attributed it to the overlap of 5 lines spaced at 23 G with the intensity distribution 1 4 6 4 I and 4 lines with the intensity distribution 1 3 3 1. Their simultaneous appearance was ascribed to two possible monomer additions. 

Since poly(methyl methacrylate) radicals terminate by disproportionation, the polysiloxane-polyMMA block copolymers may not have the multiblock structures the polysiloxane-polystyrene block copolymers have. Instead they might be expected to have BAB triblock or AB diblock structures. In accord with this expectation, the poly-siloxane-polyMMA blocks prepared (Table III) have narrow molecular weight distributions, Mw/Mn 2, and monomodal GPC curves. 

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