Ethanol-Mediated Living Radical Homo- and Copolymerizations with Cp*-Ruthenium Catalysts: Active, Robust, and Universal for Functionalized Methacrylates

With judiciously selected hgands (phosphines) and cocatalysts (amines), a series of highly active and functionality-tolerant pentamethylcyclopentadienyl (Cp*) ruthenium catalysts [Cp*Ru(CI)(LL2)-L-1 L-1 and L-2. ligands] have been developed for lime radical homo- and copolymerizations universally accessible to a variety of functional methacrylates in ethanol and related alcoholic and polar media In particular, the heand/cocatalyst combination of tri-m-tolylphosphine [P(mTo1)3, mTol = m-MeC6H5] and a hydrophilic amine, 2-chmethylamino-1-ethanol [Me2N(CH2)(2)OH. 2-DMAE], led to a very active and robust catalyst that induced fast polymerizations and line molecular-weight control (M-w/M-n < 1 2) in ethanol for not only homopolymerizations but also random or block copolymenzations with pendent-functional methacrylates carrying poly(cthyleric glycol) ( PEG), dimethylammo [-N(CH3)(2)]. and hydroxyl (-OH) groups. The accessible solvents included a wide variety of alcohols (methanol, ethanol, etc), environmentally benign and readily recoverable, in which hid) reaction rate and solution homogeneity readily were attained for the polar monomers P-31 NM R analysis on the catalyst/cocatalyst systems revealed that a part of the starting coordinatively satin ated 18c complex Cp*Ru(Cl)[P(mTol)(3)](2) is dynamically transfoi med in situ into an amine-coordinated analogue Cp*Ru(Cl)[P)(mTol)(3)](2-DMAE), and this dynamic ligand cocatalyst exchang2 may in turn generate a ti a nsient unsaturated 16e form Cp*Ru(Cl)[P(mTol)(3)] that may be the real active catalyst The products thus included homopolymers, AB- and ABC-block copolymers, and random/ statistical copolymers, the last could be extended w as many as six functional comonomers, while retaining compositional umfoi may and narrow molecular weight distributions independent of monomei conversion