Solution properties of well-defined 2-(dimethylamino)ethyl methacrylate-based (co)polymers: A viscometric approach

Well-defined poly(2-(dimethylamino)ethyl methacrylate)-based (co)polymers with various molar masses were synthesized by atom transfer radical polymerization (ATRP) using CuBr ligated with 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) as catalyst, and ethyl 2-bromoisobutyrate (EBiB) or α-methyl, ω-(2-bromoisobutyrate) poly(ethylene glycol) (mPEGx-BiB) as (macro)initiator. The solution properties of these (co)polymers were investigated by viscometry either in pure water or in concentrated buffer solutions. It comes out that reduced viscosity in pure water is strongly affected by the molar mass of poly(2-(dimethylamino)ethyl methacrylate) block but also by the quaternization degree of tertiary amino groups. In fact, a polyelectrolyte effect can only be detected when the charge density per macromolecule reaches a critical value either in terms of molar mass or quaternization degree. Fitting of viscometry data according to either Huggins or Fuoss and Fedors equation also allows calculating the intrinsic viscosity and approaching the overlap concentration.