Functional amphiphilic oligo(ethylene oxide) methacrylate-based block copolymers: Synthesis by an activator regenerated by electron transfer process for atom transfer radical polymerization and aqueous micellization

Well-defined amphiphilic block copolymers (ABPs) consisting of poly(oligo(ethylene oxide) monomethyl ether methacrylate) (POEOMA) and poly(tert-butyl methacrylate) (PtBMA) were successfully synthesized using an activator regenerated by electron transfer (ARGET) process for atom transfer radical polymerization (ATRP). Two synthetic routes starting from the synthesis of either PtBMA or POEOMA macroinitiators followed by chain extension with the alternate monomer were examined. The results from a kinetic investigation suggest that both ARGET ATRP of OEOMA and subsequent chain extension with tBMA proceed in a living manner, yielding functional POEOMA-block-PtBMA ABPs in the presence of various functional initiators. As a preliminary evaluation for a polymer-based drug delivery system, the functional ABPs were examined for aqueous micellization through self-assembly that allows for the preparation of colloidally stable micellar aggregates with various corona morphologies. For flower-like micelles bearing disulfide linkages in the center of hydrophilic loops, the reductive cleavage of the disulfide linkages enables a facile conversion to thiol-decorated micelles without a measurable change in particle size.