Energy migration experiments in diblock copolymer micelles and brushes were proposed. Expressions for the transient donor and acceptor fluorescence intensities and the energy-trapping efficiency were derived for the described experiments. By following the proposed data treatment procedure, the core radii of micelles and the thickness of a brush layer can be evaluated. The dependence of energy migration coefficient D-m on n(D), the number of donor groups in each chain, can be used to check the validity of the proposed models.