Synthesis and Characterization of Polymer Brushes of Poly(N,N-dimethylacrylamide) from Polystyrene Latex by Aqueous Atom Transfer Radical Polymerization

Abstract

Negatively charged polystyrene latex was synthesized, and a copolymer shell of 2-(methyl-2‘-chloropropionato)ethyl acrylate (HEA-Cl) and styrene was added, from which poly(N,N-dimethylacrylamide) (PDMA) was polymerized by atom transfer radical polymerization in aqueous suspension at room temperature. Increasing monomer concentration in the presence of CuCl or CuBr and one of three ligands (N,N,N‘,N‘,N‘ ‘-pentamethyldiethylenetriamine (PMDETA), 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA), and tris[2-(dimethylamino)ethyl]amine (Me6TREN)) produced grafts whose molecular weight increased to over 600 000 and polydispersities in the range of 1.3−1.8, determined from chains recovered following cleavage by base. Hydrodynamic brush thicknesses were 70−800 nm, and average chain separations, calculated from Mn and the mass of polymer recovered per particle, varied from 4.0 to 1.1 nm. Very high grafting densities were achieved with good molecular weight control, the highest densities yet reported for high m...