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Stereospecificity of Alkaline Earth Metal Compounds in the Anionic Polymerization of N,N ‐Dimethylacrylamide
Author(s) -
Nakhmanovich Boris I.,
Urman Yakov G.,
ArestYakubovich Alexander A.
Publication year - 2001
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20010501)202:8<1327::aid-macp1327>3.0.co;2-w
Subject(s) - alkaline earth metal , polymerization , tacticity , polymer chemistry , chemistry , anionic addition polymerization , counterion , polymer , magnesium , alkali metal , barium , ionic polymerization , coordination polymerization , metal , inorganic chemistry , organic chemistry , radical polymerization , ion
N,N ‐Dimethylacrylamide (DMA) was polymerized with several initiators containing alkaline earth metal compounds such as dibutylmagnesium, calcium alkoxyalkoxide, bis(triphenylmethyl)barium, and magnesium and barium alkoxyalanates. The organobarium initiators, like the organolithium ones, give mainly isotactic, THF‐insoluble and partially crystalline polymer, whereas the structure and properties of the polymer obtained with R 2 Mg are similar to those reported for the Cs‐initiated polymer. The isotactic triad content is determined by the nature of the alkaline earth metal used, and is almost independent of the presence of aluminium in the active center, and of the replacement of THF solvent by toluene. Therefore, the stereospecificity of the Group II metal compounds, with respect to the formation of isotactic poly(DMA), increases with increasing counterion radius which is opposite to the tendency found for the polymerization with alkali metals. The situation is similar to that in the anionic polymerization of butadiene, where the effect of the counterion size on polymer structure for alkaline earth initiators is also opposite to that found with alkali metals.