The ABC miktoarm star terpolymer MPEG-PTHF(-PDMA) was synthesized by the combination of click chemistry

atom transfer radical polymerization (ATRP) and cationic ring opening polymerization (CROP).A block copolymer of poly(ethylene glycol) (PEG) and poly(N

N-dimethylaminoethyl methacrylate) (PDMA) which bears an azido at diblock junction (MPEG-N3(-PDMA)) was first prepared by atom transfer radical polymerization.Then

an alkynyl-terminated narrow distributed polytetrahydrofuran (PTHF-Alk) was synthesized as another building block via cationic ring opening polymerization.The well-defined ABC miktoarm star shaped terpolymer was afforded by clicking MPEG-N3(-PDMA) onto the chain end of PTHF-Alk.The structure of the star terpolymer was characterized by the FTIR

NMR and SEC/MALLS.The self-assembly behavior of the polymer were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM).This star shaped terpolymer consists of a hydrophobic PTHF chain

a hydrophiphilic PEG chain and another stimuli-responsive PDMA chain.It can self-assemble into micelles with different sizes and morphologies at various pH values

such as 5.0

7.4 and 9.5.The micellar size also exhibits temperature-dependence at pH 7.4 and 9.5.The variation of size and morphology of the micelles with the solution pH and temperature is ascribed to the pH- and thermo-responsive properties of the PDMA block.