Solid-state NMR has been used to investigate the structure, dynamics, and morphology of the polyrotaxane prepared by polymerizing acrylonitrile in the presence of 60-crown-20. For solid poly [(acrylonitrile)(n)-rotaxa-(60-crown-20)(x)] with x/n = 0.01, the 60-crown-20 was found to be phase-separated, amorphous, and highly mobile at room temperature. 2D WISE NMR revealed the presence of less mobile crown segments that were attributed to those in contact with the rigid PAN phase at the interfacial regions. Compared to unthreaded PAN, the T-g of the host backbone was slightly depressed (90 degrees C vs 110 degrees C), as measured by solid-state H-1 NMR. These PAN T-g values were undetectable with DSC. Dipolar magnetization transfer (i.e., spin diffusion) experiments on the polyrotaxane revealed typical smallest diameters of 6-8 nn for the 60-crown-20 domains and NMR long periods of 20-26 nm. The long periods were compared with electron density correlation lengths computed from SAXS data. Upon heating the polyrotaxane to 80 degrees C, the primary change in the domain structure was a reduction in the size of the interface. A physical blend of PAN and 60c20 was also found to be phase separated, with a sharper interface than the polyrotaxane.