An Approach for the Sphere-to-Rod Transition of Multiblock Copolymer Micelles

The shape of polymer micelles is important for pharmaceutical applications as drug delivery. In this article, an approach inducing sphere-to-rod transition of multiblock polyurethane micelles has been developed through introducing a second hydrophilic component phosphatidylcholine group into the polymer chains. Time-resolved dynamic light scattering (DLS), combined with transmission electron microscopy (TEM), was employed to investigate the kinetics of morphology transition. Moreover, a dissipative particle dynamics (DPD) simulation method was applied to study the mechanism of sphere-to-rod transition. These experimental and simulation studies revealed that the hydrophilic phosphatidylcholine groups can create defects on the surfaces of spherical polyurethane micelles, thus, making positive contribution to adhesive collisions and leading to the fusion of spherical micelles into rod-like micelles. This finding provides new insight into the origins of rod-like polymer micelles, which is valuable for the design and preparation of novel polymeric drug carriers with tailored properties.