EFFECT OF THE NATURE OF THE ALKYL GROUP OF INITIATION AND TERMINATIONIN R(3)AL RLI INITIATION OF METHYL-METHACRYLATE/

The polymerisation of methyl methacrylate has been investigated with m ixed aluminium and lithium alkyls. The use of sterically hindered alum inium alkyls such as triisobutyl aluminium in conjunction with tert-bu tyl lithium leads to living polymerisation at 0 degrees C with little complications from secondary initiation or premature termination. The use of less bulky alkyl groups on either aluminium or lithium leads to both secondary initiation, as observed by the formation of high molec ular weight polymer by GPC-LALLS and termination via cyclisation as ob served by MALDI-TOF-MS. The initiator efficiencies, even when living p olymerisation ensues, are considerably less than 100%.