Designing Miktoarm Polymers Using a Combination of “Click” Reactions in Sequence with Ring-Opening Polymerization

Abstract

The design and synthesis of a well-defined molecular building block with three orthogonal functionalities which facilitate the construction of ABC-type miktoarm star polymers via a combination of sequential CuI-catalyzed cycloaddition of an azide to an alkyne (“click”) followed by ring-opening polymerization are reported. Using this simple and highly versatile methodology, a variety of miktoarm star polymers were prepared which consisted of hydrophilic poly(ethylene glycol) and hydrophobic polystyrene and poly(ε-caprolactone) arms. Their self-assembly in an aqueous medium was examined using dynamic light scattering and transmission electron microscopy. These ABC miktoarm polymers were found to self-assemble into spherical micelles whose core size and hydrodynamic diameter were found to be inversely proportional to the size of the PEG arm. The potential of encapsulating small molecules into these micelles was explored using Disperse Red 1 dye. An enhancement in the loading capacity of the micelles was observed with an increase in the length of the hydrophobic arm.