Metal-free anionic polymerization of methyl methacrylate

Results on the metal-free anionic polymerization of methyl methacrylate (MMA) are presented. MMA was polymerized in tetrahydrofuran, using tetrabutylammonium diethyl 2-ethylmalonate and tetrabutylammonium 2-nitropropanate as initiators. Immediate polymerization was observed only in cases where the initators did not contain traces of their precursor molecules, the presence of which causes an appreciable inhibition period. This is attributed to the transfer reaction between active species and the precursor molecules. Only after their consumption can the major polymerization start. Using very pure initiators, no inhibition period was observed. Curves from dilatometric measurements showed the existence of an induction period. As usual, this is attributed to an initiation reaction which is slower than the propagation reaction. It is more clearly marked for tetrabutylammonium diethyl 2-ethylmalonate than for tetrabutylammonium 2-nitropropanate as initiator. All polymerizations of MMA usually go to complete cons...