Novel approaches and schematic models have been used to provide insights in viewing lamellar assembly in ring-banded spherulites of a model polymer poly(ethylene adipate) (PEA) via correlations between the outer-surface and three-dimensional interior morphology. When crystallized at 28 °C, PEA in thick bulk forms exhibits a ring-banded top surface with bowl-like and dome-like height profile centering on its nucleus. The three-dimesional periodical assembly leads to not only the noticeable ring bands on exterior surfaces but also corrugated-board-like multishell structures in the interior of the spherulites. The corrugated-board structure has been found to be composed of plate-like lamellae, which first grow in a tangential direction and then turn to a radial direction; the radial plates taper to form thinner cilia-like lamellae due to the polymer chain concentration gradient periodically precipitated during the growth. Alternating sequences of plate-like lamellae in two perpendicular orientations (bending from tangential to radial) in PEA ring-banded spherulites during growth in a radial direction account for the spherulites confined in thin films to display two contrast circumferential rings with alternating interference colors. Scanning electron microscopy dissection graphs clearly revealed interior corrugated layer thickness in bulk forms, which matches well with the inter-ring spacing in thin films.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics