Synthesis and characterization of well-defined ABC 3-Miktoarm star-shaped terpolymers based on poly(styrene), poly(ethylene oxide), and poly(ε-caprolactone) by combination of the "Living" anionic polymerization with the ring-opening polymerization

A series of well-defined ABC 3-Miktoarm star-shaped terpolymers [Poly (styrene)-Poly(ethylene oxide)-Poly(epsilon-caprolactone)](PS-PEO-PCL) with different molecular weight was synthesized by combination of the "living" anionic polymerization with the ring-opening polymerization (ROP) using macro-initiator strategy. Firstly, the "living" poly(styryl)lithium (PS-Li+) species were capped by I-ethoxyethyl glycidyl ether(EEGE) quantitatively and the PS-EEGE with an active and an ethoxyethyl-protected hydroxyl group at the same end was obtained. Then, using PS-EEGE and diphenylmethylpotassium (DPMK) as coinitiator, the diblock copolymers of (PS-b-PEO)(p) with the ethoxyethyl-protected hydroxyl group at the junction point were achieved by the ROP of EO and the subsequent termination with bromoethane. The diblock copolymers of (PS-b-PEO)(d) with the active hydroxyl group at the junction point were recovered via the cleavage of ethoxyethyl group on (PS-b-PEO), by acidolysis and saponification successively. Finally, the copolymers (PS-b-PEO)d served as the macro-initiator for ROP of e-CL in the presence of tin(II)-bis(2-ethylhexanoate)(Sn(Oct)(2)) and the star(PS-PEO-PCL) terpolymers were obtained. The target terpolymers and the intermediates were well characterized by H-1-NMR, MALDI-TOF MS, FTIR, and SEC. (c) 2007 Wiley Periodicals, Inc.