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Anionic Polymerization of Methyl Methacrylate Initiated with Chromium and Vanadium Ate Complexes Incorporating Diisopropylamide Ligand

Anionic polymerization of methyl methacrylate (MMA) was initiated with chromium and vanadium ate complexes generated by the reaction of transition metal trichloride (MCl3: M = Cr, V) with n equiv of lithium diisopropylamide (LDA) (n = 1–3) and 4-n equiv of phenyllithium (PhLi). The MCl3/n LDA/4-n PhLi systems were capable of polymerizing MMA in a living manner in tetrahydrofuran (THF) at -78°C, giving poly(methyl methacrylate)s (PMMA) with narrow molecular weight distributions (MWD) in high yield, where the number-average molecular weight (Mn) of the PMMAs increased proportionally with monomer to initiator feed ratio. Matrix-assisted laser desorption inonization time-of-flight mass spectrometry (MALDI-TOF-MS) revealed that the anionic polymerization was initiated by the nucleophilic attack of diisopropylamide (iPr2N-) group on the transition metal center of the ate complexes and the growing species was stable under the polymerization conditions.