Single Crystals Self-Assembled to Sector-Face Dendritic Aggregates by Synchrotron Microbeam X-Ray Analysis on Poly(ethylene succinate)

Poly(ethylene succinate) (PESu), upon crystallization with a morphology-modulating diluent and at low degree of supercooling, forms peculiarly novel sector-face dendritic aggregates. Delicate dissection by various microscopic techniques is used to confirm the unique differences of these two faces in the PESu dendrites. Powerful synchrotron-source generated X-ray microbeam analysis is performed to prove without doubt the nature of the single crystals that self-assemble into these two sectors, respectively. Both microscopy results and 1D/2D wide-angle X-ray patterns collectively confirm that one sector-face of the PESu dendrites is composed all fully flat-on with the single-crystal's basal face contacting the substrate and branching growth with mutual perpendicular ≈90^° angle intersections; the second face is composed fully edge-on with the prism face contacting the substrate and growth with mutual oblique 5–30^° angle intersections. The growth intersection angles are also proved by the azimuthal angles in 1D and 2D X-ray patterns.