Crystal-by-Crystal Assembly in Two Types of Periodically Banded Aggregates of Poly(p-Dioxanone)

Abstract

The exterior and interior lamellar assemblies of poly(p-dioxanone) (PPDO) crystallized at 76 °C yield the most regular ones to interpret the 3D assembly mechanisms and potential for structural coloration iridescence, which are investigated using atomic-force microscopy (AFM), and scanning electron microscopy (SEM). PPDO displays two types of ring-banded spherulites within a range of Tc with dual-type birefringent spherulites (positive and negative-type) only within a narrow range of Tcs = 70–78 °C. At Tc > 80 °C, the inter-band spacing decreases from a maximum and the crystal assembly becomes irregularly corrupted and loses the capacity for light interference. Periodic grating assemblies are probed by in-depth 3D dissection into periodically banded crystal aggregates of poly(p-dioxanone) (PPDO) to disclose such layered gratings possessing iridescence features similar to nature’s structural coloration. This work amply demonstrates that grating assembly by orderly stacked crystal layers is feasible not only for accounting for the periodic birefringent ring bands with polarized light but also the distinct iridescence by interfering with white light.

Probing the Nano-Assembly Leading to Periodic Gratings in Poly(p-dioxanone)

“…As seen from the above list, the possibility of compatibility or miscibility of PPDO with other polymers is enhanced if the candidate polymers possess hydrogen bonding to interact with the carbonyl group of PPDO. As seen in earlier studies [33], PPDO can form periodic ring bands with high regularity more easily if it is blended with suitable diluent polymers that are miscible with it. In addition to 3D microscopy dissection evidence, synchrotron radiation X-ray with a microfocal beam is a powerful tool for investigating morphology within micro-domains.…”

“…Huang et al [36] and Y.J. Huang et al [33] probed the 3D interior morphology of neat PPDO and PPDO/PESu, respectively, to shed new light on assembly mechanisms. On this basis, this study probed further, using synchrotron X-ray micro-diffraction to analyze the detailed nanoscale assembly.…”