Organization process of the hierarchical structures in microbially synthesized polyhydroxyalkanoates

Polyhydroxyalkanoates (PHAs) showed hierarchical structures and were used as model polymers to investigate the organization process of the high-order structures in biomaterials. Real-time Fourier transform infrared spectroscopy and optical microscopy demonstrated that helical segments formed along with the spherulite growth. Atomic force microscopy revealed the details of growth, twisting and branching of lamellar crystals. Cooperative packing of these twisting lamellae led to regular banded spherulites observed under polarized light microscopy. Real-time observation on the crystallization process provided richer information than the characterization of the final structures; consequently, it provides deeper insight into the organization mechanism of the hierarchical structures. © 2006 Elsevier B.V. All rights reserved.