Due to their unique microphase structure copolymer systems have become important potential candidates for nanolitographic purposes. In order to properly design copolymeric templates a complete characterization of the phase separated system is required. Due to the fact that structural analysis of organic compounds remains demanding, especially when it comes to nanometer scale features such as interfacial spaces, there are very often at least two complementary experimental techniques employed to fully characterize observed morphologies. In this work diblock copolymers of poly (styrene)-b-poly (ethylene oxide) (PS-PEO) with three different molecular weights were investigated. Two different experimental methods were used: nuclear magnetic resonance spectroscopy (NMR) and atomic force microscopy (AFM). AFM topographic images of self-assembled polymer films enabled estimation of average interdomain distances, whereas the NMR spin diffusion experiment provided structural parameters related to stiff PS domains and interfacial space thickness. An application of two complementary methods enabled complete description of the studied morphologies and revealed substantial differences in polymer chain mobility between two distinct phases.