Tough, bio-inspired hybrid materials.

The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs that are extremely difficult to replicate synthetically. We emulate nature's toughening mechanisms by combining two ordinary compounds, aluminum oxide and polymethyl methacrylate, into ice-templated structures whose toughness can be more than 300 times (in energy terms) that of their constituents. The final product is a bulk hybrid ceramic-based material whose high yield strength and fracture toughness [ approximately 200 megapascals (MPa) and approximately 30 MPa.m(1/2)] represent specific properties comparable to those of aluminum alloys. These model materials can be used to identify the key microstructural features that should guide the synthesis of bio-inspired ceramic-based composites with unique strength and toughness.