Carbonyl compounds polymerization-blocking

GTP constitutes an example of Michael addition polymerization involving the addition of a silyl ketone acetal to a,p-unsaturated carbonyl compounds in the presence of a nucleophilic or Lewis acid catalyst Due to the living nature of GTP, the method was applied successfidly to the synthesis of well-defined random, block-graft, star-shaped polymers as well... 

DHA works because of a reaction between its carbonyl group and a free amino group (—NH3+) of several amino adds in the skin protein keratin. Amino adds are the building blocks of the biological polymers called proteins (Chapter 19) keratin is just one such protein. The DHA produces brown-colored compounds called melanoids when it bonds to the keratins. These polymeric melanoids are chemically linked to cells of the stratum corneum, the dead, outermost layer of the skin. DHA does not penetrate this outer layer so the chemical reaction that causes tanning only affects the stratum corneum. As this dead skin sloughs off, so does your tan ... 

Methyl Methacrylate. The most generally usefiil initiator for anionic polymerization of MMA and related compounds is 1,1-diphenylhexyllithium which is formed by the quantitative and facile addition of butyllithium with 1,1-diphenylethylene (DPE) (eq. 17) (46). Using this initiator in THF at -78°C, it is possible to polymerize MMA to obtain polymers and block copolymers with predictable molecular weights and narrow molecular weight distributions. Controlled polymerizations are not effected in nonpolar solvents such as toluene, even at low temperatures. Other usefiil initiators for polymerization of MMA are oligomers of (a-methylstyryl)lithium whose steric requirements minimize attack at the ester carbonyl group in the monomer. These initiators are also useful for the polymerization of 2-vinylpyridine (see Methacrylic Ester POLYMERS). 

Major commercial synthetic specialty polymers are made by chain-growth polymerization of functionalized vinyl monomers, carbonyl monomers, or strained ring compounds. Depending on monomer structure, the polymerization may be initiated free radically, anionically, or cationically. Copolymers or terpolymers with random, alternating, block, or graft sequences can be prepared under appropriate reaction conditions. There are numerous mediods used to prepare specialty polymers in the research laboratory. However, only a few are of commercial interest. Of particular commercial interest is synthesis of specialty polymers in solutions, dispersions, suspensions, or emulsions. 

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