writer：Jia, Z. F.; Zhou, Y. F.; Yan, D. Y.*
keywords：amphiphiles;atom transfer radical polymerization (ATRP);hyperbranched;ring-opening polymerization;self-assembly;star-block copolymer
source：期刊
specific source：J. Polym. Sci., Part A: Polym. Chem. 2005, 43, 6534. http://onlinelibrary.wiley.com/doi/10.1002/pola
Issue time：2005年
Novel amphiphilic star-block copolymers, star poly(caprolactone)-block-poly[(2-dimethylamino)ethyl methacrylate] and poly(caprolactone)-block-poly(methacrylic acid), with hyperbranched poly(2-hydroxyethyl methacrylate) (PHEMA–OH) as a core moiety were synthesized and characterized. The star-block copolymers were prepared by a combination of ring-opening polymerization and atom transfer radical polymerization (ATRP). First, hyperbranched PHEMA–OH with 18 hydroxyl end groups on average was used as an initiator for the ring-opening polymerization of ε-caprolactone to produce PHEMA–PCL star homopolymers [PHEMA = poly(2-hydroxyethyl methacrylate); PCL = poly(caprolactone)]. Next, the hydroxyl end groups of PHEMA–PCL were converted to 2-bromoesters, and this gave rise to macroinitiator PHEMA–PCL–Br for ATRP. Then, 2-dimethylaminoethyl methacrylate or tert-butyl methacrylate was polymerized from the macroinitiators, and this afforded the star-block copolymers PHEMA–PCL–PDMA [PDMA = poly(2-dimethylaminoethyl methacrylate)] and PHEMA–PCL–PtBMA [PtBMA = poly(tert-butyl methacrylate)]. Characterization by gel permeation chromatography and nuclear magnetic resonance confirmed the expected molecular structure. The hydrolysis of tert-butyl ester groups of the poly(tert-butyl methacrylate) blocks gave the star-block copolymer PHEMA–PCL–PMAA [PMAA = poly(methacrylic acid)]. These amphiphilic star-block copolymers could self-assemble into spherical micelles, as characterized by dynamic light scattering and transmission electron microscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6534–6544, 2005