The development of polymeric drug delivery devices began five decades ago, starting with hydrogels in 1960. After that, nano-sized drug carriers were developed to increase the efficiency of the drug uptake. This has been accomplished by encapsulating the drug in polymer carriers that increase the circulation time of the drug in the blood, preventing early adsorption, elimination and targeting the drug where it needs to be delivered. One of the most important strategies to increase the circulation time of nanocarriers is PEGylation, in which poly(ethylene glycol) coats the device to prevent premature elimination from the bloodstream due to protein attachment. The goal of this project is to compare the protein adsorption onto polymeric micelles that have either a cyclic or a linear architecture on the hydrophilic coating. We synthesized PEG-b-PCL amphiphilic diblock copolymers in which the poly(ethylene glycol) block is hydrophilic and the PCL block is hydrophobic. First, PEG macroinitiators were synthesized with either cyclic or linear architectures. The macroinitiators were then used for ring-opening polymerization of e-caprolactone. These diblock copolymers were self-assembled into micelles suspended in water by a co-solvent evaporation method. These two types of polymers (no end groups and end groups) allowed us to study the role of polymer architecture on protein adsorption and circulation time.