Using small-angle neutron scattering, we investigated the mechanism of molecular exchange in spherical micelles formed by diblock copolymers in an organic solvent. Not only does temperature affect the micelle exchange rate in the expected manner, but increasing the core block length by 60% produced a remarkable 10,000-fold decrease in the exchange rate. This work provides fundamental understanding of block copolymer micelle dynamics, and is important for a host of potential applications of these hybrid macromolecules, including drug delivery.
