Neutron spin echo spectra of poly(ethylene oxide) (PEO) melts confined in porous silicon (the mean pore diameter: 13 nm) were recorded at Q = 0.05, 0.08, and 0.11 Å-1 and successfully analyzed in terms of a two-state model, where chains adsorbed to the pore walls exhibit much slower internal dynamics than in the bulk and their centers-of-mass do not move, while free chains have bulklike internal dynamics and diffuse within an infinite cylinder in the center of the pore. The radius of this cylinder was found to be 1.4 nm for PEO 3 kg/mol (3k); this corresponds to the thickness of the adsorbed layer to be approximately equal to the Flory radius. As opposed to PEO 10k, for which details on the center of mass diffusion could not be discerned, for PEO 3k the diffusion rate along the pore was found to be smaller than that in the radial direction.
