Atom transfer radical polymerizations of methyl methacrylate catalyzed by EBiB/SnCl2·2H2O(FeCl2·4H2O)/FeCl3·6H2O/MA5-DETA systems

The ATRP of methyl methacrylate (MMA) with the system of FeCl2·4H2O, N,N,N′,N″,N″-penta(methyl acylate)diethylenetriamine (MA5-DETA) and ethyl 2-bromoisobutyrate (EBiB) showed high activity and is not well-controlled. The addition of a certain amount of FeCl3·6H2O as the additive into the above system results in the decrease of the polymerization rate and the improvement of the controllability. When SnCl2·2H2O was added instead of FeCl2·4H2O, a novel catalyst system SnCl2·2H2O/FeCl3·6H2O/EBiB/MA5-DETA formed shows better controllability, higher catalytic activity and higher initiating efficiencies (more than 90%) in comparison with the system FeCl2·2H2O/FeCl3·6H2O/EBiB/MA5-DETA. The polydispersities of the polymers kept range from Mw/Mn=1.18–1.26. The real active species in the new system is Fe (II) formed from the reaction of FeCl3·6H2O with the active radical species produced from the reaction of SnCl2·2H2O with EBiB.