R. Duchateau, Wj Wouter van Meerendonk, L. Yajjou
Oct 18, 2006
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0
Influential Citations
29
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Journal
Macromolecules
Abstract
Two ester-functionalized cyclohexene oxide monomers (3,4-cyclohexene-oxide-1-carboxylic acid methyl ester (1) and 3,4-cyclohexene-oxide-1-carboxylic acid phenyl ester (2)) could be copolymerized with CO2 using the β-diketiminato zinc catalyst (EtBDI)ZnOEt (EtBDI = 2-(2,6-diethylphenyl)amido-4-(2,6-diethylphenyl)imino-2-pentene) under mild conditions. MALDI-ToF-MS microstructure analyses of the formed aliphatic polycarbonates revealed the occurrence of chain transfer reactions to both monomer and polymer as a result of zinc-catalyzed transesterifications. As a consequence, branched and cyclic polymer structures were formed, which limited the molecular weight development and led to an increase in the polydispersity. The zinc catalyst is also capable of transesterifying carbonate functionalities, albeit that the transesterification rate is considerably lower than that for ester functionalities and only becomes visible at high conversion. This was supported by independent catalytic transesterification reactio...