Ring-opening polymerizations structure-reactivity

Thus, confirmation of whether the product obtained in an attempted reaction in a true random copolymer is important to clarify the mechanism of the propagation reaction and to correlate structure and reactivity in ring-opening polymerizations. Considering that apparent copolymers may be formed by reactions other than copdymerization, for example, by ionic grafting or by combination of polymer chains, characterization of cross-sequences appears to be one of the best ways to check the formation of random copolymers. 

Structure-Reactivity Relationships in Ring-Opening Polymerization... 

Correlations of structures and reactivities for anionic and cationic ring-opening polymerization are reviewed. The following topics are discussed chemical structure of active species and their isomerism, determination of active centers concentration, covalent vs ionic growth and correlations between structures of active centers or monomers and their reactivities. 

Correlations of structures and reactivities require for the ring-opening polymerization as well as for other ionic polymerizations approaches differing from these in radical polymerization of the unsaturated monomers. This is because in radical polymerization free radicals are the unique chemical structure of the growing species and double bonds are the only chemical groups involved in polymerization (1), C ). ... 

Tsuruta, T. Structure-reactivity relationship of catalysts for ring-opening polymerization of some oxiranes. Pure Appl. Chem. 1981,55,1745-1751. 

Compounds such as [Al(R)(OC6H3Bu2-2,6)2] will carry out the polymerization of methyl and ethyl methacrylate when activated with t-BuLi. The nature of the alkyl group was found to affect the tacticity of the polymer. The tetraphenylporphinato aluminium phenoxide has been shown to be active for the ring opening polymerization of epoxides and lactones. The reaction is accelerated by the presence of reagents such as MAD. An adduct [Al(OC6H2Bu2-2,6-Me-4)Me2(methyhnethacrylate)] relevant to this reactivity has been isolated and structurally characterized. ... 

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