The molecular dynamics of a set of polysulfone polymers have been studied with broadband dielectric spectroscopy. The materials comprise main-chain polysulfones attached to semifluorinated (SF) oxydecylperfluorodecyl side chains. Through the analysis of the dielectric data together with information from differential scanning calorimetry and small-angle X-ray scattering, it can be shown that the oxydecylperfluorodecyl side chains are microphase-separated and form nanodomains with an independent dynamic glass-transition (delta(SF)) relaxation. In addition to the a process (which is the glass transition of the main chain), other relaxation processes can be detected with Arrhenius-type activation energies of 38-90 +/- 2 kJ/mol. A gamma(SF) process, observed only in polysulfone with SF side chains, can be assigned to librational fluctuations of the perpendicular component of the fluoroalkyl group. A gamma beta relaxation reflects fluctuations of the dipole moments (O=S=O and C=O) of the polymer, whereas a process, with high activation energies (>70 +/- 2 kJ/mol), is assigned to packaging defects in the material. A detailed description of the processes is provided together with a proposed relaxation scheme. (C) 2007 Wiley Periodicals, Inc.