We report QENS measurements from PS-b-PFOA aggregates in supercritical CO2. Line shapes are dominated by localized diffusive modes and segmental dynamics of the anchored, finite-length PFOA chains. For Q=0.6 angstrom-1, we obtain effective diffusion coefficients of ?0.8 10-6 cm2/s. At higher Q, a single component is not sufficient as shown by excess intensity on the flanks. For Q=1.5 angstroms-1, the wings reflect contributions due to a distribution of faster, more localized chain modes.