Thermo-Sensitive Poly(p-dioxanone) Banded Spherulites with Controllable Patterns for Iridescence

Poly(p-dioxanone) (PPDO) is widely recognized to be a bioabsorbable material for biomedical applications, and its crystalline morphology is dependent on the crystallization temperature and polymorphism. The PPDO ringless spherulite (RLS, at Tc = 30–40 °C) has a mixture of α′- and α-crystals, while the α-crystal is predominant in the ring-banded spherulite (RBS) (Tc = 60–78 °C). The interior structure of PPDO-RBS is characterized by microbeam X-ray and interior-dissected morphology analysis. The double ring-banded RBS consists of horizontal lamellae beneath valleys and vertical lamellae in the ridges. Optimal band spacing and the ridge-valley height difference produce photonic iridescence colors in PPDO-RBS at 60–70 °C. Additionally, ring-band growth patterns can be customized from 2.9 to 10.9 μm by tuning the temperature program. Thus, custom-tailoring the crystal growth produces multiple and versatile combinations of ring-banded patterns in a wide range of orders for inducing the photonic reflection behavior.