Alumina additives for fast iron-mediated AGET ATRP of MMA using onium salt as ligand
Three kinds of alumina (acidic, neutral, and basic Al2O3) were effective as additives for the control and rate enhancement of iron-mediated AGET (activators generated by electron transfer) ATRP (atom transfer radical polymerization) of methyl methacrylate (MMA) in the presence of limited amount of air, using FeCl3·6H2O as the catalyst, tetrabutylammonium bromide or tetra-n-butylphosphonium bromide as the ligand, ethyl 2-bromoisobutyrate as the initiator, and ascorbic acid as the reducing agent. The conversion could be up to 83.9% in the case of basic Al2O3 and 75.3% with neutral Al2O3 only in 13 h, respectively, whereas no polymer could be obtained even in 50 h without additives. The polymers obtained with neutral and basic Al2O3 had controlled molecular weights and low Mw/Mn values (∼1.2). Tacticities of the as-prepared PMMA in the presence of these three kinds of Al2O3 were consistent with that obtained from conventional free-radical polymerization of MMA. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011