writer：Weizhong Yuan, Jinying Yuan, Sixun Zheng, Xiaoyin Hong
keywords：Dendritic star-block copolymer, pH sensitivity, Controllable drug release
source：期刊
Issue time：2007年

A series of well-defined dendritic star-block copolymers were successfully synthesized by combination of living ring-opening polymerization
(ROP) and atom transfer radical polymerization (ATRP) with the hydroxyl-terminated dendrimer polyester. Dendritic star-shaped poly(L-lactide)s
(PLLAs) were prepared by bulk polymerization of L-lactide (L-LA) with dendrimer polyester initiator and tin 2-ethylhexanoate catalyst. The
number-average molecular weight of these polymers linearly increased with the molar ratio of L-LA to dendrimer initiator. Dendritic star-shaped
PLLA was converted into a PLLABr macroinitiator with 2-bromopropionyl bromide. Dendritic star-block copolymers could be obtained via
ATRP of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA). The molecular weight distributions of these copolymers were narrow. The molecular
weights of dendritic star-shaped polymers and star-block copolymers could be controlled by the molar ratios of monomer to initiator and
monomer conversion. The thermal properties of these dendritic star-shaped polymers and star-block copolymers were investigated. The behavior
of model drug chlorambucil release from the copolymer indicated that the rate of drug release could be effectively controlled by altering the pH
values of the environment.