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

Abstract

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 T c = 30–40 °C) has a mixture of α′- and α-crystals, while the α-crystal is predominant in the ring-banded spherulite (RBS) (T c = 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.

From Nano-Crystals to Periodically Aggregated Assembly in Arylate Polyesters—Continuous Helicoid or Discrete Cross-Hatch Grating?

“…The temperature-dependent periodic morphologies of the PDT showed a systematic trend of variation at T c = 80–120 °C. Iridescence experiments on the PDT crystallized at these Tc were performed in accordance with the procedures and setup for white light interference as documented in the relevant literature [ 34 , 35 , 36 ]. Figure 13 a–e show POM images (upper row) and iridescence photo shots (lower row), where the iridescence spectra generally took a softer hue color due to the lesser order of the assembly in the crystallized neat PDT films.…”

Leveling up Organic Semiconductors with Crystal Twisting

“…When d A and d B , commensurate with the twisting pitch, P, approach the wavelength of visible light, iridescence can be observed. Iridescence has been previously observed in banded spherulites of poly(pdioxanone), 131 poly(ethylene adipate), 132 poly(3-hydrobutyrate), 133 and mannitol, 134 among others.…”

Universality in interior periodic assembly of banded d-(−)-poly(3-hydroxybutyrate) justified with the iridescence test

“…A recent study has shed new light that a periodic architecture can be composed of lamellae that branch or spawn new crystals periodically and some lamellae change their orientation alternately at periodic intervals, instead of propositions of continuous helix-twist lamellae. 21 Newer approaches by interior 3D dissection [22][23][24][25][26][27][28][29][30][31] and synchrotron microbeam X-ray analysis 31,32 have been demonstrated to be useful for better insights of probing the crystal-assembly mechanisms. Earlier studies in the literature indicate that phase-separated domains in lamellae may confine and alter the arrangement of lamellae during aggregation of crystals.…”

“…16 Similarly, the PHB crystallization behaviour may change after addition of other amorphous polymers as diluents; that is to say, the morphology of PHB can be manipulated to display the desired crystal assembly patterns. The periodically banded morphology is very typical in PHB or its blends, as well as in many other semicrystalline polymers such as biodegradable poly(pdioxanone) (PPDO), 32 and aliphatic polyesters, polyethylene (PE), 16,22,[25][26][27][28][29][30][31][33][34][35] etc. Further observation of the interlamellar crevices in the periodically banded PHB by SEM microscopy techniques 30,31 has proved that PHB exhibits periodic bands composed of vertically-oriented lamellae and horizontally-oriented plates underneath the alternating ridge-valley bands.…”

“…Newer approaches by interior 3D dissection 22–31 and synchrotron microbeam X-ray analysis 31,32 have been demonstrated to be useful for better insights of probing the crystal-assembly mechanisms. Earlier studies in the literature indicate that phase-separated domains in lamellae may confine and alter the arrangement of lamellae during aggregation of crystals.…”