Monomer complex participation

The monomer complex participation (MCP) mechanism suggests that alternation results from homopolymerization of a 1 1 complex formed between donor and acceptor monomers [Cowie, 1989 Furukawa, 1986] ... 

Another model used to describe deviations from the terminal model involves the participation of a comonomer complex (Sec. 6-3b-3) [Cais et al., 1979 Coote and Davis, 2002 Coote et al., 1998 Seiner and Litt, 1971]. The comonomer complex competes with each of the individual monomers in propagation. The monomer complex participation model involves eight... 

The complexed monomer does not propagate. Models based on mechanisms (1) and (2) are known respectively as the monomer-monomer complex participation (MCP) and dissociation (MCD) models. Mechanisms (3) and (5) would result in a solvent effect analogous to a bootstrap effect (see below), while mechanism (4) would result in a model similar to the MCD model, though it would be based on a slightly different equilibrium expression. The MCP and MCD models are outlined in the following paragraphs. 

The Monomer-Monomer Complex Participation (MCP) Model was first suggested by Bartlett and Nozaki (16), later developed by Seiner and Litt (17), and refined by Cais and co-workers (18). In this model, it is assumed that the two monomers can form a 1 1 donor-acceptor complex and add to the propagating chain as a single unit in either direction. Assuming that the terminal unit is the only unit affecting radical reactivity, eight addition reactions and an equilibrium constant are required to describe the system. 

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