Atom transfer radical polymerization (ATRP) is a well-known method to synthesize polymers with high chain end functionality and low molecular weight distributions (MWD). To further push the limits of ATRP it is imperative to continually strive towards the synthesis of more active catalysts. The activity of Cu based ATRP catalysts have been shown to correlate very well with the reduction potential (E1/2) of the complex. It is now well established that the addition of electron donating groups (EDG) such as amino or ether groups to the ligand significantly decreases the reduction potential and therefore increases activity. Two of the most active ligands commonly utilized in ATRP, tris(pyridin-2-ylmethyl)amine (TPMA) and tris[2-(dimethylamino)ethyl]amine (Me6TREN), have been used in this study as ligand scaffolds. Substitution of TPMA in the para position with electron donating groups resulted in highly reducing copper complexes with E1/2 values less than -400 mV resulting in the most active catalyst to date. Reaction of tris(2-aminoethyl)amine (TREN) with substituted benzyaldehydes, subsequently followed by reduction, resulted in highly active Me6TREN based complexes which gave linear kinetics and MWD < 1.3 at low ppm amounts of Cu. Various low ppm methods of ATRP were conducted with Me6TREN and TPMA based ligands which gave polymers with high molecular weight and high chain end functionality. Full characterization of the synthesized ligands and complexes including 1H and 13C NMR, UV-Vis spectroscopy, cyclic voltammetry and X-Ray diffraction (where applicable) were conducted.

Development of highly active copper catalysts for atom transfer radical polymerization (ATRP)

248th National Meeting (2014)

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