Synthetic mother-of-pearl may join the growing list of advanced materials

A team of researchers at ETH Zurich (Zurich, Switzerland) have been working to develop synthetic mother-of-pearl. Also known as nacre, mother-of-pearl is one the hardest, stiffest, most stable materials found in nature.

ETH researchers from the Group for Complex Materials led by André R. Studart have been investigating and imitating the substance’s brick-and-mortar like structure, which is characterized by stacked Calcium carbonate plates, which are connected with mineral “bridges,” and filled with a biopolymer that acts like mortar.

The researchers reportedly use tiny aluminum oxide plates (a few dozen micrometers in size) and epoxy resin as the “mortar.” A rotating magnetic field is used to align the magnetized plates, which are suspended in an aqueous solution, in one direction. Resin is then added and the material is solidified under high pressure and temperatures of around 1000º C. The resulting composite material is said to have a similar microstructure to natural mother-of-pearl.

To make the structure even more stable, titanium oxide is added to the surface of the aluminum oxide plates. Because titanium oxide has a lower melting point than aluminum oxide, it forms droplets on the platelets, which mimic the mineral “bridges” found in mother-of-pearl.

The density of the bridges can reportedly be adjusted using temperature and pressure to producer desired levels of strenght, stiffness and fracture toughness. The researchers at ETH claim they have been able to create a substance that is comparable in stiffness to carbon-fiber composites. 

Possible applications for the material may include construction, aircraft and space.