The development of the morphology of polybutadiene/poly(2 -vinyl naphthalene) blends in five proportions by mass (5, 10, 50, 90, and 95%, w/w) is studied by epifluorescence and scanning electron microscopy (SEM) techniques. The phase separation process of these immiscible polymers produces a primary morphology that is formed by dispersed droplets in a continuous matrix. In the sequence a secondary phase separation inside the primary domains is detected by epifluorescence microscopy of the intrinsically fluorescent domains. Secondary phase separation is confirmed by SEM fracture surface analysis. The relative size of the droplets and the matrix composition depend on the proportion of the components of the blends. The mechanism of the phase separation process is preferentially by nucleation growth for either primary or secondary phase separation processes. Secondary relaxation processes involving the poly(2-vinyl naphthalene) phase are studied by fluorescence spectroscopy. The profile of the steady-state excimer fluorescence of poly(2-vinyl naphthalene) with the temperature in the blend differs from that of the isolated bomopolymer and is explained by the contribution from the interface to the radiationless deactivation. The Arrhenius plot for the temperature dependence exhibits slope changes that are related to the polymer relaxation processes.