Periodic Hierarchical Structures in Poly(p-dioxanone) Modulated with Miscible Diluents: Top-Surface and Interior Analyses

Morphologies and top-surface and interior lamellar arrangement of biodegradable polyesters, poly(p-dioxanone) (PPDO) blended with poly(ethylene succinate) (PESu), have been investigated. The PPDO/PESu (75/25) blend system shows three different types of nuclei co-existing at T_c= 75 °C: double-spiral, single-spiral, and concentric rings. For double-spiral spherulites, the lamellae turn into feather-like branches on the ridge which are arranged along the radial direction and then submerge to the valley following bending away to the tangential direction consistent with the spiral direction. On the other hand, the interior structure is composed of both radially oriented lamellae and tangentially oriented lamellae. A novel technique by specimens etching and tilting on sample stages was adopted to dissect into the interior 3D structures PPDO crystallized from the PPDO/PESu blend, wherein stereo-dissection scanning electron microscopy analysis and top-surface atomic-force microscopy characterization are performed on the novel periodic assembly in PPDO. Detailed 3D-assembly is proved by direct morphology dissection evidence for probing the mechanisms of the complexed architectures never reported or discovered before for this polymer.