HIERARCHICAL STRUCTURE OF COLLAGEN COMPOSITE SYSTEMS - LESSONS FROM BIOLOGY

Hierarchical structure in biocomposite systems such as in collagenous connective tissue have many scales or levels, have highly specific interactions between these levels, and have the architecture to accommodate a complex spectrum of property requirements. As examples, the hierarchical structure-property relationships are described in three soft connective tissues; tendon, intestine and intervetebral disc. In all instances, we observed numerous levels organization with highly specific interconnectivity and with unique architectures that are designed to give the required spectrum of properties for each oriented composite system. From these lessons in biology, the laws of complex composite systems for functional macromolecular assemblies are considered. Finally, demonstrations of the application of these laws to simple synthetic composites are given including continuous multilayered polymeric materials, liquid crystalline polymers and "hard elastic" membranes. It is shown that structure-property relationships can only be described, and in some instances predicted, if these complex synthetic materials are accurately defined in terms of their hierarchical structure.