Periodic self-assembly of lamellae in ring-banded polymer spherulites (RBS) has been a long-term challenge to understand the fundamental mechanisms since 1950s. This speech covers a comprehensive review on the plausibility and novelty of the mechanisms of crystal packing in several widely studied polymers, as well as small-molecule compounds for comparative reinforcement, are analyzed in details. Biodegradable poly(L-lactic acid) (PLLA), poly(b-hydroxybutyrate) (PHB) and poly(p-dioxanone) (PPDO), etc. To perceive 3D ring-banded spherulites (RBS), the assemblies are characterized using a polarized optical microscope (POM), atomic-force microscopy (AFM), scanning electron microscopy (SEM), synchrotron-radiation microbeam wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS), etc. The interior assemblies reveal a universal packing into periodicity via fratal-repetitive growth of branches coupled with lamellar widening and occassional twisting and bending. Horizontally oriented branching lamellae are assembled in valleys, where the length of these horizontal lamellae crystal increases with respect to T_c. From each end of this horizontal lamellar crystal, vertically oriented lamellae are packed underneath the ridges periodically. Novel proposals of 3D-interior lamellae self-assembly arrangement of crystal-by-crystal assembly with periodically fractals leading to varieties of polymeric architectures potentially acting similarly to photonic crystals. Furthermore, the polymer crystals with orderly banding periodicity in grating architectures can act as structural crystals for iridescence colourful spectra.

Eamor M. Woo received Ph.D. degree from University of Texas at Austin (Austin, Texas, USA) and is Chair Professor in National Cheng Kung University (NCKU), Taiwan. He has published over 275 highly cited original papers and major review articles, three book chapters and edited books. He has received numerous distinguished academic honors/awards, and is elected Fellow in Taiwan’s Polymer Society and Fellow in Chem. Eng. Society. He is Senior Editor for Journal of Polymer Research (Springer-Nature), also served as Guest Editors “Crystals”, and “Polymers”, and Editorials board members in several journals.