Synthesis of ABC-type miktoarm star polymers by “click” chemistry, ATRP and ROP

ABC-type miktoarm star polymers, poly(ethylene oxide)-block-polystyrene-block-poly (ε-caprolactone)s (PEO-b-PS-b-PCL) were synthesized via combination of “click” chemistry, atom-transfer radical polymerization (ATRP) and ring opening polymerization (ROP). Azide ended PEO arms, PEO–N3, and a trifunctional molecule, propargyl 2-hydroxylmethyl-2-(α-bromoisobutyraloxymethyl)-propionate (PHBP), were prepared first, respectively. A “click” reaction of PEO–N3 and PHBP generated a PEO macroinitiator, PEO–(Br)(OH) with two functionalities, one is hydroxyl group and the other is α-bromoisobutyraloxyl group. Consecutive ATRP of styrene (St) and ROP of ε-caprolactone (ε-CL) from the PEO macroinitiator produced the PEO-b-PS-b-PCL miktoarm stars. All the structures of the polymers were determined.