Cage structure radical polymerization

These examples demonstrate the well-known process of polymerization initiated by anion-radicals. Our next consideration is devoted to an unusual case of initiation. Intercalation of fullerenes by metals results in the formation of fullerene-metal derivatives. Paramagnetic metallofullerenes (anion-radicals) are the fullerenes doped with endohedral metal. According to calculations and structural studies, LaCs2, for example, contains La in the center of one hexagonal ring of the fuller-ene cage (Akasaka et al. 2000, Nishibori et al. 2000, Nomura et al. 1995). Intrafullerene electron transfer in metallofullerenes is possible (Okazaki et al. 2001). 

A similar variation in the quantum yield of the Norrish type I process is illustrated in Figure 3 for solid copolymers of ethylene containing three different ketone structures. The ketone groups in the backbone of the polymer chain in ethylene- copolymers show much lower quantum yields than those from the secondary or tertiary structures induced by copolymerization of methyl vinyl ketone and methyl isopropenyl ketone with ethylene. (See Table I, structures I, II and III.) In the latter two cases, the Norrish type I cleavage produces a small radical and a polymer radical, and it seems likely that the small radical has a much greater probability of escaping the cage than when the radicals produced are both polymeric, as in the case of structure I. 

This puts the final radicals at least 4.5 A apart outside the primary cage. As a result the radical pairs do not recombine. In looking for reactive structures that could serve as photolabile side groups, this was an important consideration because cage recombination is an important factor in viscous media such as those used in the polymerization of polyfunctional acrylates. 

Syntheses, structures, and chemistry of various peroxides were described thoroughly in the literature [5]. Here will only be mentioned some properties of peroxides and their performance as they pertain to initiations of polymerizations. Decompositions of peroxides, such as the azo compounds, are also temperature dependent [6]. This means that the rates increase with temperature. The rates are also influenced by the surrounding medium, such as the solvents that imprison or cage the produced pairs of free radicals. Before undergoing a net translational diffusion out of the cage, one... 

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