Nano-assembly of intertwining lamellae of opposite bending senses in poly(ethylene oxide) co-crystallizing with poly(p-vinyl phenol)

Strongly interacting amorphous poly(p-vinyl phenol) (PVPh) was added into semi-crystalline poly(ethylene oxide) (PEO) at 20 wt.% to generate dendritic lamellae of alternating birefringence colors, which intertwine roughly in the radial directions as periodic stripes. Optical and atomic-force microscopy analyses are performed on revealing lamellae assembly in highly dendritic PEO spherulites by crystallizing PEO/PVPh (80/20) at crystallization temperature (T_c) equals to 45 °C. The lamellae of two opposite colors in the same PEO spherulite quadrant are exactly of same geometry (of elongated plates, each being 0.2 μm in width and 2–5 μm in length), but they fan out +/−45^o, respectively, as they grow away from the radial direction. The opposite colored-lamellae are radiating out in radial directions, interweaving each other to display alternating colors in radial alignment. However, such alternating colors can also be similarly seen in ring-banded spherulites in many polymers. The results presented in this study have demonstrated that the lamellae of alternating birefringent colors cannot only be seen in banded spherulites, but also in spherulites with radial dendrites.