Nitroxide-Mediated Living Radical Polymerization of 2-Hydroxyethyl Acrylate and the Synthesis of Amphiphilic Block Copolymers

Nitroxide-mediated radical polymerizations of 2-hydroxyethyl acrylate (HEA) were performed in bulk, in organic solvent ( N, N -dimethylformamide), and in aqueous media at 100−120 °C, using an alkoxyamine initiator based on N - tert -butyl- N -(1-diethyl phosphono-2,2-dimethylpropyl) nitroxide, SG1. By the addition of free nitroxide (6−12 mol% with respect to the initiator), the polymerizations were controlled, exhibiting a linear relationship of ln([M] 0 /[M]) vs time and M n vs conversion up to 50−60% conversion. Poly(HEA) with M n ≈ 90 000 and M w / M n < 1.3 can be obtained by bulk polymerization. Solution polymerizations of HEA in N, N -dimethylformamide and in water exhibit comparable kinetics to those of HEA bulk polymerizations at the same temperature. Chain transfer to polymer produced up to 1.7 mol% branches for poly(HEA) depending on the reaction conditions, with a trend of increasing long chain branching with conversion. Amphiphilic block copolymers of poly(BA- b -HEA) with different molecular weights and block composition were synthesized from a poly( n -butyl acrylate) (pBA) macroinitiator.