The experiment and dissipative particle dynamics simulation were carried out on four polymers with different block ratios for the investigation of the structure-property relationship of (poly(epsilon-caprolactone)(2)-[poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)](2) [(PCL)(2)(PDEA-b-PPEGMA)(2)] micelles. The miktoarm star polymers assembled into spherical micelles composed of PCL core, pH-sensitive PDEA mesosphere and poly (ethylene glycol) methyl ether methacrylate (PPEGMA) shell. When decreasing pH from 7.4 to 5.0, the hydrodynamic diameter and transmittance of (PCL)(2)(PDEA-b-PPEGMA)(2) micelles increased along with globule-uneven-extended conformational transitions, owing to the protonation of tertiary amine groups of DEA at lower pH conditions. Doxorubicin (DOX) was mainly loaded in the pH-sensitive layer, and more DOX were loaded in the core when increasing drug concentrations. The in vitro DOX release from the micelles was significantly accelerated by decreasing pH from 7.4 to 5.0. The results demonstrated that the pH-sensitive micelles could be used as an efficient carrier for hydrophobic anticancer drugs, achieving controlled and sustained drug release. (c) 2014 American Institute of Chemical Engineers AIChE J, 60: 3634-3646, 2014