Biomimetically Structured Lamellae Assembly in Periodic Banding of Poly(ethylene adipate) Crystals

Nature tends to assemble hierarchical structures in similar ways to achieve compactness and functions. This work probes the interior lamellae assembly of crystalline spherulites of poly­(ethylene adipate) (PEA) with striking birefringence patterns versus some known biological structures for optical color diffraction. Three-dimensional dissecting onto interior lamellar structures of spherulites in poly­(ethylene adipate) (PEA) in bulk forms crystallized at 28 ± 3 °C were studied in correlation with thin-film forms. Interior morphology in bulk PEA samples revealed periodic hemisphere or arc-shaped layers resembling corrugate boards with liner-flute medium alteration. Interior spherulites clearly expose that the lamellae within the intralayer are kebabs (plates) in the radial direction while the interlayer region are thin sheaths (fibrils) composed of cilia-like lamellae in the tangential direction. The interior repetitive lamellar assembly of PEA banded spherulites in displaying periodic optical birefringence patterns is proven to highly resemble those in many biological structures for iridescence light interference.