Investigation of methyl methacrylate and vinyl acetate polymerization promoted by Al(Bu-i)(3)/2,2 '-bipyridine and Al(Bu-i)(3)/2,2 '-bipyridine/TEMPO complexes
UNSPECIFIED. (1998) Investigation of methyl methacrylate and vinyl acetate polymerization promoted by Al(Bu-i)(3)/2,2 '-bipyridine and Al(Bu-i)(3)/2,2 '-bipyridine/TEMPO complexes. MACROMOLECULES, 31 (21). pp. 7133-7141. ISSN 0024-9297Full text not available from this repository.
Results of methyl methacrylate (MMA) and vinyl acetate (VOAc) polymerization using the Al(Bu-i)(3)/2,2'-bipyridine/TEMPO initiating system at room temperature failed to confirm the "living" radical mechanism reported earlier. Several species apparently propagate without control in a normal free radical process and only above a critical initiator concentration. No evidence was found for the penta- and hexacoordinated aluminum species previously suggested, but high conversion to an alkoxyamine was observed. Additionally, mixing Al(Bu-i)(3) and BIPY promotes a variety of reactions involving alkyl and hydride transfers to the aromatic rings forming reduced BIPY products, along with a persistent organoaluminum radical. All these results illustrate that the process is considerably more complicated than postulated before. Conversely, at -78 degrees C, a single active species excluding the participation of TEMPO has been put, in evidence, displaying some "living" characteristics. Several experiments support its anionic nature, as previously suggested by Ikeda.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry|
|Journal or Publication Title:||MACROMOLECULES|
|Publisher:||AMER CHEMICAL SOC|
|Official Date:||20 October 1998|
|Number of Pages:||9|
|Page Range:||pp. 7133-7141|
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