Biomimetic materials: recent developments in organic-inorganic hybrids

There are a variety of biological materials that are composites of ceramics and organic phases, and successfully combine impressive toughness with high modulus and strength. This behavior is in contrast to the general situation with synthetic composites, where toughness is generally found to decrease with increase in modulus and tensile strength. Preserving toughness is very important in many applications, as very high strength cannot be exploited if a material is sensitive to small amounts of damage. The structures-properties relationships documented in biomaterials may provide guidance for improving the performance of synthetic composites, in a type of biomimicry. This paper identifies some key aspects of such biomimetic designs in natural fibers and composites, and describes some efforts in the recent past to duplicate structures and properties in synthetic composite materials, particularly with regard to toughness.