Nanostructured amphiphilic segmented networks based on poly(1,3-dioxolane) (PDXL) and poly(methyl methacrylate) (PMMA) have been synthesized by radical copolymerization of alpha,omega-diacrylate PDXL with methyl methacrylate (MMA). The corresponding polymer blends have been prepared by the radical polymerization of MMA in the presence of alpha,omega-dihydroxy-PDXL. The multiphase behavior of the segmented networks and polymer blends have been compared by making use of solid-state C-13 CP/MAS NMR spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetrical analysis (TGA). For the network structures, the combined analysis of the proton spin-lattice relaxation times (T-1H) and proton spin-lock relaxation times (T-1rhoH) revealed small PDXL domain sizes between 1 and 20 nm. DSC and DMA analysis also showed the forced compatibility of the network components. In the case of the polymer blends, the phase morphology strongly depends on the PDXL weight fraction. For blends with PDXL fractions higher than 20 wt %, T-1H relaxometry, DSC, and DMA analysis evidenced the presence of a heterogeneous phase morphology (domain sizes > 20 nm) that allows for the crystallization of the PDXL-rich domains.