Preparation of well-defined poly[(ethylene oxide)-block-(sodium 2-acrylamido-2-methyl-1-propane sulfonate)] diblock copolymers by water-based atom transfer radical polymerization

Well-defined poly[(ethylene oxide)-block-(sodium 2-acrylamido-2-methyl-1- propane sulfonate)] diblock copolymers [P(EO_m-b-AMPS_n)], have been obtained by water-based ATRP using α-memoxy-ω-(2- methylbromoisobutyrate) poly(ethylene oxide)s (MeO-P[EO]_m-Br ⁱB with m ranging from 12 to 113) and CuBr · 2Bpy (Bpy for 2,2′-bipyridyl) as macro-initiator and catalytic complex, respectively. Compared to direct polymerization in water, it has been demonstrated that the water/ methanol (3:1, v/v) mixture is better suited for predicting the final number-average molar mass from the initial monomer-to-macroinitiator molar ratio and achieving a quite narrow poly-dispersity, even at high monomer conversion (M̄_w/M̄_n ≈ 1.4 at 80% conversion). The effect of temperature, solvent mixture composition and addition of NaCl salt on the polymerization rate and extent of control over the copolymer molecular parameters have been highlighted as well.