A series of well-controlled triblock methoxy poly(ethylene glycol)-b-poly(ε-caprolactone)-b- poly[2-(dimethylamino) ethyl methacrylate] (MePEG-b-PCL-b-PDMAEMA) was obtained by ring open polymerization (ROP) and atom transfer radical polymerization (ATRP) methods. Their structures and composition were confirmed by ¹H nuclear magnetic resonance (¹H NMR), and the molecule weight and molecular weight distribution of the copolymers were obtained by ¹H NMR and gel permeation chromatography (GPC). The thermal stability, crystallization property and hydrophiphilicity were evidenced by thermogravimetric analysis, X-ray diffraction (XRD) and static water contact angle measurements. The formation of the nanoparticles was studied by ¹H NMR in D₂O and fluorescence probe method. The transmission electron microscopy (TEM) displayed that the morphologies of the nanoparticles were spherical and the size was on nano scale. Dynamic light scattering (DLS) indicated that the nanoparticles were in the range of 40～70 nm, and in different pH solution, the nanoparticles showed good pH-sensitivity. Due to the hydrophobic core and the cationic hydrophilic shell, the nanoparticles has great potential application for the codelivery of hydrophobic drugs and negative drugs.

Key words: atom transfer radical polymerization (ATRP), self-assembly, amphiphilic, pH-responsive