Iron-Catalyzed Suspension Living Radical Polymerizations of Acrylates and Styrene in Water

Iron(II)-catalyzed suspension living radical polymerizations of acrylates and styrene have been achieved for the first time in water. In the presence of a large amount of water (water/organic = 1/1 v/v), a half-metallocene type iron complex [Fe(Cp)I(CO) 2 ] induced a smooth polymerization of n -butyl acrylate in conjunction with (CH 3 ) 2 C(CO 2 Et)I as an initiator to give polymers of narrow molecular weight distributions (MWDs) ( M w / M n = 1.2−1.3) and controlled number-average molecular weights, in direct proportion to monomer conversion. Reaching 90% conversion in 4 h, the polymerizations proceeded much faster than in toluene without water. Similarly, methyl acrylate, tert -butyl acrylate, and styrene were polymerized with the same initiating system under aqueous suspension conditions to afford living polymers of controlled molecular weights and narrow MWDs ( M w / M n = 1.2−1.3). The suspension systems can be applied to the controlled synthesis of block and random copolymers of acrylates and styrene.