The Chemistry of Radical Polymerization table

The Chemistry of Radical Polymerization Table 3.5 Selected Kinetic Data for Decomposition of Peroxides ... 

Some characteristics of initiators used for thermal initiation arc summarized in Table 3.1. These provide some general guidelines for initiator selection. In general, initiators which afford carbon-ccntcrcd radicals e.g. dialkyldiazcncs, aliphatic diacyl peroxides) have lower efficiencies for initiation of polymerization than those that produce oxygen-centered radicals. Exact values of efficiency depend on the particular initiators, monomers, and reaction conditions. Further details of initiator chemistry are summarized in Sections 3.3.1 (azo-compounds) and 3.3.2 (peroxides) as indicated in Table 3,1. In these sections, we detail the factors which influence the rate of decomposition i.e. initiator structure, solvent, complexing agents), the nature of the radicals formed, the susceptibility of the initiator to induced decomposition, and the importance of transfer to initiator and other side reactions of the initiator or initiation system. The reactions of radicals produced from the initiator arc given detailed treatment in Section 3.4. 

Most of the cases discussed above are related to the use of polystyrene, but surface segregation is a universal phenomenon and can be transposed to other systems. Table 5.3 reports a non-exhaustive list of binary blends in which segregation occurred and in which the surfaces were decorated with functional groups. End-functional fluoro polymers are commonly developed via different chemistries (ring opening, controlled radical or anionic polymerization) and used as surface... 

The concept of copolymerizing with a functional comonomer that is soluble in the continuous phase can virtually be extended to any vinyl functional monomer, provided that under such conditions the copolymerization parameters will allow a copolymerization to occur. The functionalities available using hydrophobic monomers with functional monomers in direct miniemulsions are summarized in Table 15.1. Latexes with a double functionality were prepared via a free-radical polymerization of divinylbenzene in miniemulsion [49, 50] after polymerization, the remaining vinyl bond might be reacted with a thiol-functionalized PEG via the thiol-ene chemistry [49]. 

As was shown above, the interaction of high-energy rays with monomers results in the generation of free radicals. In radiation chemistry, the yield of a reaction is generally expressed in terms G values, that is, the number of radiolytically produced or consumed species per 100 eV absorbed. As far as radical vinyl polymerization is concerned, G(radical) values depend on the proneness of a monomer to form radicals. Thus, for styrene, G(radical) values of 0.7 are found for vinyl acetate, the G(radical) value amounts to —12 (see Table 1). 

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