Summary: Novel biomimetic surfactants based on cholesterol as the hydrophobic segment and poly[2-(methacryloyloxy) ethyl phosphorylcholine] (pMPC) as the hydrophilic segment were synthesized in the present study by atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)-ethyl phosphorylcholine (MPC) using a cholesterol-based macroinitiator. The association behavior of cholesterolblock-poly[2-(methacryloyloxy)ethyl phosphorylcholine] (Chol-pMPCs) in aqueous solution was studied by 1H NMR spectroscopy, fluorescence probe technique, and atomic force microscopy (AFM). The 1HNMRspectrum of the polymer in CD3OD showed both the cholesterol group and the phosphorylcholine group while the cholesterol group did not appeared in the 1H NMR spectrum of the polymer in D2O, which implied the formation of a micelle structure. Fluorescence excitation spectra of a pyrene probe solubilized in the aggregates of Chol-pMPCs suggested the presence of a critical micelle concentration (cmc) in water. The critical micelle concentrations of the polymers CMPC10, CMPC20 and CMPC40 were determined to be 7.27×10-3, 13.47×10-3, and 20.77×10-3mg•mL-1, respectively. AFM images of the aggregates on mica suggested that the pMPC block formed the biocompatible micelle coronas and the cholesterol block formed the hydrophobic micelle cores. These newbiomimetic diblock copolymers were evaluated as "stealthy" nanocapsules for the delivery of hydrophobic drugs. The anti-cancer drug adriamycin (ADR) was chosen as a hydrophobic drug to be incorporated into the inner core of the micelles and the morphology of the drug-loaded micelles were observed by AFM. Schematic of the biomimetic block copolymers and their micellization, and an AFM image of the micelles deposited on mica.