ARGET ATRP of Methyl Acrylate with Inexpensive Ligands and ppm Concentrations of Catalyst

A simple and versatile polymerization technique via activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) of methyl acrylate (MA) with inexpensive commercially available ligands, including diethylenetriamine (DETA), N,N,N',N '',N ''-pentamethyldiethylenetriamine (PMDETA), and tris(2-aminoethyl)amine (TREN), is reported. Catalytic amounts of catalyst were utilized achieving ppm levels of (CuBr2)-Br-II/L in the presence of a zerovalent copper metal (i.e., copper powder or wire) at 25 degrees C. High molecular weight poly(methyl acrylate) (PMA) could also be obtained with M-n > 1.5 million and M-w/M-n similar to 1.25. A map was generated, illustrating minimal catalyst concentrations (i.e., copper and ligand) required over a range of targeted degrees of polymerization with various ligands. Several conclusions were made: (I) lower catalyst concentrations require higher targeted degrees of polymerization to produce equally controlled polymerizations, (2) higher catalyst concentrations are necessary for lower targeted degrees of polymerization, to ensure every activation deactivation cycle adds fewer monomer units, (3) catalyst performance decreased from Me6TREN > TREN > PM DETA > DETA, and (4) degrees of polymerization >= 1000 exhibited a catalyst concentration boundary, which required higher (CuBr2)-Br-II/L catalyst concentrations to produce similarly controlled polymerizations. Successful chain extension of a PMA macroinitiator demonstrated excellent chain-end functionality and living character.