Living radical polymerization in water and alcohols: Suspension polymerization of methyl methacrylate with RuCl2(PPh3)(3) complex

Water and alcohols were employed as solvents for the living radical polymer ization of methyl methacrylate (MMA) with the R-X/RuCl2(PPh3)(3) initiating systems in the presence and absence of Al(Oi-Pr)(3) at 80 degrees C (initi ator R-X: PhCOCHCl2, CCl3Br). These Ru(II)-based systems indeed led to livi ng suspension polymerization even in such protonic solvents to give polymer s with controlled molecular weights and narrow molecular weight distributio ns ((M) over bar(w)/(M) over bar(n) = 1.1-1.3). The living polymerizations in water proceeded faster than those in toluene, and additives such as Al(O i-Pr)(3) were not necessarily required for the polymerization to occur. Esp ecially, the PhCOCHCl2/RuCl2(PPh3)(3) initiating system gave high molecular weight poly(MMA) ((M) over bar(n) similar to 10(5)) with narrow molecular weight distributions ((M) over bar(w)/(M) over bar n similar to 1.1) in wat er even without Al(Oi-Pr)(3). Similar Ru(II)-mediated living processes were feasible in such alcohols as methanol, isobutyl alcohol, and tert-amyl alc ohol under similar conditions. The success of these living suspension polym erizations in aqueous and alcoholic media attests their radical mechanism a s well as the tolerance of the ruthenium complex and the dormant carbon-hal ogen bond to water and alcohols, where transition-metal complexes are often deactivated.