Macromolecules, Vol.33, No.8, 2887-2893, 2000
Anionic polymerization of (meth)acrylates in the presence of tetraalkylammonium halide-trialkyl aluminum complexes in toluene. 2. NMR and quantum-chemical study on the structure of ester enolate complexes as models of the active center
Li-6 and C-13 NMR investigations on ethyl alpha-lithioisobutyrate (EiBLi) and quantum-chemical (DFT) calculations on methyl a-lithioisobutyrate (MiBLi) were performed to study the structure of active centers in anionic polymerization of methacrylates in toluene in the presence of tetramethylammonium chloride/triethylaluminum complexes NMe4[AlnEt3nCl] (n = 1, 2). The results support the existence of several complex species ([EiBLi.AlnEt3nCl]NMe4)(m) varying in composition (n = 1, 2) and degree of association (m = 1, 2). In the presence of methyl pivalate (MPiv), a model compound for monomer/polymer ester groups, a nonassociated complex NMe4[EiBLi.MPiv.AlEt3Cl] is preferably formed.