The evolution of the self-complexation of poly(ethylene oxide)-block-poly(methacrylic acid), PEO-block-PMAA, as a function of the degree of ionization has been studied by means of fluorescence spectroscopy and dynamic light scattering. Pyrene and naphthalene singly labeled block copolymers were used, with two different methacrylic acid block lengths. The conformation of the block copolymers changes with varying degree of ionization due to the hydrophobic nature of the methyl group of the methacrylic acid units as well as due to the hydrogen bonding that takes place between the methacrylic acid units and ethylene oxide units. The limiting degrees of ionization between the states where the block copolymers are molecularly dissolved or intra- or intermolecularly complexed were determined. The chain exchange between the self-complex particles at low degree of ionization was observed to take place via two mechanisms. Insertion and expulsion of the single chains is responsible of the faster exchange event whereas the slower chain exchange occurs by merging and splitting of the self-complex particles.