CONTROLLED SYNTHESIS OF POLY(ACRYLIC ESTERS) BY ALUMINUM PORPHYRIN INITIATORS

Polymerization of tert-butyl acrylate (1,R = C(CH3)3) with (5,10,15,20-tetraphenylporphinato)-aluminum 1-propanethiolate ((TPP)AlSPr; 2 (X = SCH2CH2CH3))as initiator at -90 to +20-degrees-C proceeded rapidly to give the polymer with M(w)/M(n) of 1.1-1.5. The living polymer of methyl methacrylate with a (porphinato)aluminum enolate growing terminal (4), prepared by the polymerization with (TPP)AlMe (2, X = CH3), also brought about the polymerization of acrylic esters such as ethyl (1,R = CH2CH3), isobutyl (R = CH2CH(CH3)2), and tert-butyl acrylates, affording the corresponding block copolymers with M(w)/M(n) ranging from 1.1 to 1.4. The living nature of polymerization was confirmed by the sequential two-stage polymerizations of tert-butyl acrylate at room temperature. The three-stage polymerizations of methyl methacrylate, tert-butyl acrylate, and methyl methacrylate or 1,2-epoxypropane initiated with (TPP)AlMe (2, X = CH3) afforded the corresponding ABA- or ABC-type block copolymer with well-defined block lengths.