Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 5: New Materials
CPP 5.9: Vortrag
Montag, 25. Februar 2008, 12:15–12:30, C 230
The isopod cuticle: A model to study the influence of the structure and chemical composition on the mechanical properties of a biological composite material — •Sabine Hild1, Andreas Ziegler1, and Othmar Marti2 — 1Central Facility for Electron Microscopy; University of Ulm, Germany — 2Experimental Physics; University of Ulm, Germany
The mineralized exoskeleton (cuticle) of crustaceans is an excellent model to study biological nano-composites. The cuticle consists of an organic matrix composed of chitin-protein fibers associated with various amounts of crystalline and amorphous calcium carbonate (ACC). Although this structural principle is ubiquitous for the cuticle of crustaceans, their mechanical properties are well adapted to their various habitats and escape strategies. To show possible adaptations of the mechanical performance of the exoskeleton to its biological requirements the chemical and structural composition of different isopod species were analyzed. Using confocal micro-Raman microscopy, SEM and SFM it was shown that for all investigated species the mineral phase is arranged in distinct layers. Calcite is restricted to the outer area of the cuticle, whereas ACC is localized in the middle having only little overlap with the calcite layer. Nano-indentation tests performed on the cross sections of the cuticle of different isopods reveals higher mechanical strength for the crystalline than for the ACC-rich phase. Our results suggest that variations in the thickness of the calcite containing layers as well as the amount of organic material leads to variations in exoskeleton hardness and flexibility.