Abstract:Poly(dimethylaminoethyl methacrylate)(PDMAEMA) macromonomers were synthesized by Atom Transfer Radical Polymerization(ATRP)，and polystyrene-g -poly(dimethyl aminoethyl methacrylate)(PS-g-PDMAEMA) was prepared by traditional free radical copolymerization of PDMAEMA macro monomer with styrene(St) using 2,2′ -azobisisobutyrnitrile(AIBN) as initiator. The concentrated dispersions were added to different mass fractions of ethanol water mixed solvents and achieved microspheres by molecule self assembly. The structure of PDMAEMA macromonomers and PS-g-PDMAEMA copolymers were characterizaed using FT-IR and 1H-NMR, and the morphology of microspheres were observed using Scanning Electron Microscope (SEM). Zeta potential of microspheres was detected with different pH values，and the Zeta potential curve was protracted. Results showed that PDMAEMA macromonomer had a controllable number average molecular weight about 14 700. The average particle size of microspheres was 0.634 μm when the mass fraction of ethanol was 0.7. Microspheres could be more stable under acid condition.