Mother of pearl, also known as nacre, is the hard iridescent coating found on the outside of pearls, and the inside of certain mollusc’s shells. Besides being a nice-looking material used for jewelry and other types of ornamentation, it’s also remarkably strong. Now, scientists from the University of Cambridge have discovered how to make the stuff themselves.
The scientists created a liquid solution composed mainly of calcium carbonate (the main ingredient in natural, mollusc-made nacre), mixed with ions and organic components. The inclusion of the last two ingredients keeps the calcium carbonate from crystallizing, as it’s precipitated from the solution to form a layer on the desired surface.
Next, a layer of “organic material” is added to that layer of precipitate – this second layer contains pores measuring ten nanometers across. Crystallization of the precipitate layer is then induced, while the covering layer of organic material remains as it was. This process is repeated a number of times, resulting in a coating made up of multiple alternating crystallized and organic layers ... just like real mother of pearl.
Although existing man-made coatings are tougher than the synthetic nacre, the fact that it can be made from inexpensive ingredients at ambient temperatures means that it could be a good choice for economical protective coatings.
“Crystals have a characteristic shape that reflects their atomic structure, and it is very difficult to modify this shape,” said Cambridge’s Professor Ulli Steiner. “Nature is, however, able to do this, and through our research we were able to gain insight into how it grows these materials. Essentially, we have created a new recipe for mother of pearl using nature's cookbook.”
A paper on the research was published yesterday in the journal Nature Materials.
Source: University of Cambridge