Anionic polymerization of methyl methacrylate in an ionic liquid

Anionic polymerization reactions of methyl methacrylate (MMA) in ionic liquids were carried out by utilizing alkyl lithium initiators such as n-butyl lithium (it-BuLi) and diphenylhexyl lithium (DPHLi). The polymerization in ionic liquids having bis(trifluoromethyl sulfonyl)amide ([NTf2]) anion did not yield poly(MMA) (PMMA), because of the deactivation of the initiator due to an attack on the trifluoromethyl group. By using 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]), the polymerization reactions proceeded. The PMMA prepared in [C(4)mim][PF6] gave low yields (5-9%), as compared with those (15-62%) obtained for PMMA prepared in tetrahydrofuran (THF), and the prepared PMMA had large polydispersity indices (congruent to 2.0). The results obtained can be attributed to the high reaction temperature (0 degrees C), in comparison to the common anionic polymerization temperature of MMA, -78 degrees C, and the reaction between the initiator and the imidazolium cation. The initiator was considered to be deactivated because the hydrogen atom at the 2-position of the imidazolium ring was withdrawn by the alkyl lithium initiator. The tacticity of the obtained PMMA, prepared in [C(4)mim][PF6] by utilizing DPHLi, was rich in mm triads, similar to that polymerized in toluene. Copyright (C) 2008 John Wiley & Sons, Ltd.