Facile synthesis of AB2-type miktoarm star polymers through the combination of atom transfer radical polymerization and ring-opening polymerization

A novel miktofunctional initiator (1), 2-hydroxyethyl 3-[(2-bromopropanoyl)oxyl-2-{[(2-bromopropanoyl)oxylmethyll-2-methyl-propanoate, possessing one initiating site for ring-opening polymerization (ROP) and two initiating sites for atom transfer radical polymerization (ATRP), was synthesized in a three-step reaction sequence. This initiator was first used in the ROP of E-caprolactone, and this led to a corresponding polymer with secondary bromide end groups. The obtained poly(E-caprolactone) (PCL) was then used as a macroinitiator for the ATRP of tert-butyl acrylate methyl methaerylate, and this resulted in AB(2)-type PCL-[poly(tert-butyl acrylate)](2) or PCL-[poly(methyl methacrylate)], miktoarm star polymers with controlled molecular weights and low polydispersities (weight-average molecular weight/number-average molecular weight < 1.23) via the ROP-ATRP sequence. (c) 2004 Wiley Periodicals, Inc.