Multifunctional Initiators for the Ruthenium-Mediated Living Radical Polymerization of Methyl Methacrylate: Di- and Trifunctional Dichloroacetates for Synthesis of Multiarmed Polymers

Bi- and trifunctional dichloroacetates were synthesized from the corresponding multifunctional alcohols or phenols and then employed as multifunctional initiators for the living radical polymerizations of methyl methacrylate mediated by RuCl 2 (PPh 3 ) 3 in the presence of aluminum compounds such as Al(O i Pr) 3 and Al(acac) 3 (acac: acetylacetonate). All these systems led to living polymerizations. However, the systems with Al(O i Pr) 3 involved partial transesterification of the ester units in the initiators, which resulted in the formation of a monofunctional initiator. In contrast, new systems with Al(acac) 3 did not induce such transesterification and produced the multiarmed living polymers. 1 H NMR analysis showed that polymers obtained with the di- and trifunctional esters possessed almost two and three arms, respectively, along with controlled molecular weights and their narrow distributions.