Highly ordered nano-scale structure in nacre of green-lipped mussel Perna canaliculus

Abstract

The ability of the complex hierarchical structure of nacre to withstand huge work of fracture beyond its constituent materials has generated much interest in its growth mechanism and biomimicry studies. However, the structural features directly involved in the robust mechanical properties have not been successfully identified or emulate in biomimetic materials. In the current article, we present the characterisation of a novel nanostructure framework in nacre of Perna canaliculus after chemical etching. The inner structure of the nacre platelet reveals a crystalline three-dimensional framework of orientated fibrous aragonite crystals, which shows that the hierarchical structure at the nano-scale level is much more complex than researchers previously thought. Fracture analysis shows that the fibrous aragonite framework remains largely intact, which indicates the strengthening nature of the elusive internal structure. The discovery of the nano-scale highly ordered structure could be the key to understanding the toughening mechanism in nacre and could serve as a guide to the future biomimetic design of nacre-like, high strength, tough, composite materials.